MAP602_Experimental Psychology

MASTER OF ARTS (PSYCHOLOGY) EXPERIMENTAL PSYCHOLOGY MAP602

MASTER OF ARTS (PSYCHOLOGY) EXPERIMENTAL PSYCHOLOGY MAP602 Dr. M.K. Purushothama Dr. Dinesh Kumar

CHANDIGARH UNIVERSITY Institute of Distance and Online Learning Course Development Committee Chairman Prof. (Dr.) R.S. Bawa Vice Chancellor, Chandigarh University, Punjab Advisors Prof. (Dr.) Bharat Bhushan, Director, IGNOU Prof. (Dr.) Manjulika Srivastava, Director, CIQA, IGNOU Programme Coordinators & Editing Team Master of Business Administration (MBA) Bachelor of Business Administration (BBA) Co-ordinator - Prof. Pragya Sharma Co-ordinator - Dr. Rupali Arora Master of Computer Applications (MCA) Bachelor of Computer Applications (BCA) Co-ordinator - Dr. Deepti Rani Sindhu Co-ordinator - Dr. Raju Kumar Master of Commerce (M.Com.) Bachelor of Commerce (B.Com.) Co-ordinator - Dr. Shashi Singhal Co-ordinator - Dr. Minakshi Garg Master of Arts (Psychology) Bachelor of Science (Travel & TourismManagement) Co-ordinator - Ms. Nitya Mahajan Co-ordinator - Dr. Shikha Sharma Master of Arts (English) Bachelor of Arts (General) Co-ordinator - Dr. Ashita Chadha Co-ordinator - Ms. Neeraj Gohlan Master of Arts (Mass Communication and Bachelor of Arts (Mass Communication and Journalism) Journalism) Co-ordinator - Dr. Chanchal Sachdeva Suri Co-ordinator - Dr. Kamaljit Kaur Academic and Administrative Management Prof. (Dr.) Pranveer Singh Satvat Prof. (Dr.) S.S. Sehgal Pro VC (Academic) Registrar Prof. (Dr.) H. Nagaraja Udupa Prof. (Dr.) Shiv Kumar Tripathi Director – (IDOL) Executive Director – USB © No part of this publication should be reproduced, stored in a retrieval system, or transmitted in any form or by any means, electronic, mechanical, photocopying, recording and/or otherwise without the prior written permission of the author and the publisher. SLM SPECIALLY PREPARED FOR CU IDOL STUDENTS Printed and Published by: Himalaya Publishing House Pvt. Ltd., E-mail: [email protected], Website: www.himpub.com For: CHANDIGARH UNIVERSITY Institute of Distance and Online Learning CU IDOL SELF LEARNING MATERIAL (SLM)

Experimental Psychology Credits: 3 Course Code: MAP602 Course Objectives:  Students will learn to describe the principles of how we pay attention to certain types of information, but not other.  They will understand the way our senses and brain interpret the environment in psychologically meaningful units and various theories.  They will understand the role of various theories of learning and their empirical role to enhance the various processes of learning.  They will understand the rationale, strengths and limitations of the experimental method of gaining knowledge about mental and behavioural processes. Syllabus Unit 1 – Experimental Psychology: Nature and History, Experimental Method Design Unit 2 – Contribution of Weber, Fechner, Wundt and Galton Unit 3 – Sensory Processes: Structure and Function of Eye and Ear Unit 4 – Sensory Processes: Structure and Function of Olfactory Unit 5 – Sensory Processes: Structure and Function of Gustatory and Kinesthetic Unit 6 – Perception: Nature, Determinants, Perceptual Organization and Perceptual Constancy Unit 7 – Psychophysics: Basic Concepts and Methods of Classical Psychophysics Unit 8 – Signal Detection Theory: Basic Concept, Assumptions and Applications Unit 9 – Learning Theories: Classical Conditioning, Instrumental Conditioning, Hull, Tolman and Guthrie Unit 10 – Discrimination Learning: Phenomena and Paradigms Unit 11 – Verbal Learning: Nature and Determinants CU IDOL SELF LEARNING MATERIAL (SLM)

Text Books and Reference Books: 1. Amato, M.R. (1979), Experimental Psychology: Methodology, Psychophysics and Learning, New Delhi: Tata McGraw Hill. 2. Goldstein, B.E. (2002), Sensation and Perception, USA: Wadsworth. 3. Solso, R.L. (2001), Cognitive Psychology, Singapore: Pearson Education. 4. Baddley, A. (1997), Human Memory: Theory and Practice, New York: Psychology Press. 5. McGuigan, F.J. (1969), Experimental Psychology, New Delhi Prentice Hall of India Pvt. Ltd. 6. Osgood, C.E. (1953), Method and Theory in Experimental Psychology, New York: Oxford Press. 7. Kling, J.W. and Riggs, L.A. (1984), Woodworth and Schlosberg Experimental Psychology, New Delhi: Khosla Publishing House. 8. Singh, A.K. (1997), Uchhtar Samanya Manovigyan, Varanasi: Motilal Banarasidas. CU IDOL SELF LEARNING MATERIAL (SLM)

CONTENTS 1 - 30 31 - 72 Unit 1: Experimental Psychology 73 - 111 Unit 2: Contribution of Weber, Fechner, Wundt and Galton 112 - 127 Unit 3: Sensory Processes: Structure and Function of Eye and Ear 128 - 147 Unit 4: Sensory Processes: Structure and Function of Olfactory 148 - 173 Unit 5: Sensory Processes: Structure and Function of Gustatory and Kinesthetic 174 - 193 Unit 6: Perception 194 - 205 Unit 7: Psychophysics 206 - 237 Unit 8: Signal Detection Theory 238 - 249 Unit 9: Learning Theories 250 - 267 Unit 10: Discrimination Learning 268 - 269 Unit 11: Verbal Learning References CU IDOL SELF LEARNING MATERIAL (SLM)

Experimental Psychology 1 UNIT 1 EXPERIMENTAL PSYCHOLOGY Structure: 1.0 Learning Objectives 1.1 Introduction 1.2 Meaning and Scope of Experimental Psychology 1.3 Nature of Experimental Psychology 1.4 History of Experimental Psychology 1.5 Understanding Experimental Psychology 1.6 Experimental Method Design 1.7 Design of Experiments 1.8 Scales of Measurement for Psychological Experiments 1.9 Experimental Instruments 1.10 Summary 1.11 Key Words/Abbreviations 1.12 LearningActivity 1.13 Unit End Exercises (MCQs and Descriptive) 1.14 References CU IDOL SELF LEARNING MATERIAL (SLM)

2 Experimental Psychology 1.0 Learning Objectives After studying this unit, you will be able to:  Explain the basic concepts  Discuss the design of experimental methods 1.1 Introduction Experimental psychology examines relationships between human behavior and the mind. Experimental psychology is centered on fact-based, scientific research and experimentation. Therefore, experimental psychologists manipulate research variables in order to discover relationships between cognition and behavior. Experimental psychology explores basic concepts, such as memory and motivation, in many areas, such as child, social and educational psychology. Almost all experimental psychology work is conducted in controlled environments, such as university research labs. While every branch of psychology strives to understand human behavior and thought, experimental psychology solely focuses on controlled experiments with designated variables, test subjects and statistical results. 1.2 Meaning and Scope of Experimental Psychology Meaning of Experimental Psychology Experimental psychology refers to work done by those who apply experimental methods to psychological study and the processes that underlie it. Experimental psychologists employ human participants and animal subjects to study a great many topics, including sensation and perception, memory, cognition, learning, motivation, emotion; developmental processes, social psychology, and the neural substrates of all of these. Scope of Experimental Psychology The scope of Experimental Psychology is widening with the invention of new tools and instruments for experiments. Therefore, it is in the fitness of things that experimental psychology constitutes compulsory part of courses of psychology for the under-graduate and post-graduate students in universities everywhere in the world. Experimental Psychology studies external behavior CU IDOL SELF LEARNING MATERIAL (SLM)

Experimental Psychology 3 as well as the internal processes of the different stages of human development. Only those phenomenon fall outside its field which cannot be studied in controlled situations. The most important areas covered by experimental psychology include psycho-physics, animal psychology, learning psychology, psychology of individual differences, child psychology, educational psychology, clinical psychology, industrial psychology, etc. Due to the development of experimental psychology, other branches of psychology have managed to also develop their breadth of knowledge. 1.3 Nature of Experimental Psychology Nature of Experimental Psychology can be summarized as follows: 1. Experimental psychology is important because the findings discovered by psychologists play a vital role in our understanding of the human mind and behavior. 2. Experimental psychology is the scientific and empirical approach to the study of the mind. 3. The experimental approach means that tests are administered to participants, with both control and experimental conditions. 4. Experimental psychology is concerned with testing theories of human thoughts, feelings, actions, and beyond any aspect of being human that involves the mind. 5. This ultimately meant that mental perception is responsive to the material world – the mind doesn’t passively respond to a stimulus (if that was the case, there would be a linear relationship between the intensity of a stimulus and the actual perception of it), but is dynamically responsive to it. 6. Wilhem Wundt is often credited with being “the father of experimental psychology” and is the founding point for many aspects of it. He began the first experimental psychology lab, scientific journal, and ultimately formalized the approach as a science. 7. Experiments using this list, concerning learning and memory, would take up much of Ebbinghaus’ career, and help cement experimental psychology as a science. There are CU IDOL SELF LEARNING MATERIAL (SLM)

4 Experimental Psychology many other scientists’ whose contributions helped pave the way for the direction, approach, and success of experimental psychology. 8. Experimental psychology features at least three central components that define it: empiricism, falsifiability, and determinism. These features are central to experimental psychology but also many other fields within science. 9. Experimental psychology, a method of studying psychological phenomena and processes. The experimental method in psychology attempts to account for the activities of animals (including humans) and the functional organization of mental processes by manipulating variables that may give rise to behavior; it is primarily concerned with discovering laws that describe manipulable relationships. 10. The experimental psychologist deals with normal, intact organisms; in biological psychology, however, studies are often conducted with organisms modified by surgery, radiation, drug treatment, or long-standing deprivations of various kinds or with organisms that naturally present organic abnormalities or emotional disorders. 1.4 History of Experimental Psychology Experimental psychology emerged as a modern academic discipline in the 19th century when Wilhelm Wundt introduced a mathematical and experimental approach to the field. Wundt founded the first psychology laboratory in Leipzig, Germany. Other experimental psychologists, including Hermann Ebbinghaus and Edward Titchener, included introspection among their experimental methods. Charles Bell Charles Bell was a British physiologist, whose main contribution was research involving the nervous system. He wrote a pamphlet summarizing his research on rabbits. His research concluded that sensory nerves enter at the posterior (dorsal) roots of the spinal cord and motor nerves emerge from the anterior (ventral) roots of the spinal cord. Eleven years later, a French physiologist Francois Magendie published the same findings without being aware of Bell’s research. Due to Bell not publishing his research, this discovery was called the Bell-Magendie law. Bell's discovery disproved the belief that nerves transmitted either vibrations or spirits. CU IDOL SELF LEARNING MATERIAL (SLM)

Experimental Psychology 5 Ernst Heinrich Weber Weber was a German physician who is credited with being one of the founders of experimental psychology. Weber’s main interests were the sense of touch and kinesthesis. His most memorable contribution to the field of experimental psychology is the suggestion that judgments of sensory differences are relative and not absolute. This relativity is expressed in “Weber’s Law,” which suggests that the just noticeable difference, or jnd is a constant proportion of the ongoing stimulus level. Weber’s Law is stated as an equation: I  k I Gustav Fechner Fechner published in 1860 what is considered to be the first work of experimental psychology, “Elemente der Psychophysik.” Some historians date the beginning of experimental psychology from the publication of “Elemente.” Weber was not a psychologist, and it was Fechner who realized the importance of Weber’s research to psychology. Fechner was profoundly interested in establishing a scientific study of the mind-body relationship, which became known as psychophysics. Much of Fechner’s research focused on the measurement of psychophysical thresholds and just noticeable differences, and he invented the psychophysical method of limits, the method of constant stimuli, and the method of adjustment, which are still in use. Oswald Külpe Oswald Külpe is the main founder of the Würzburg School in Germany. He was a pupil of Wilhelm Wundt for about twelve years. Unlike Wundt, Külpe believed experiments were possible to test higher mental processes. In 1883, he wrote Grundriss der Psychologie, which had strictly scientific facts and no mention of thought. The lack of thought in his book is odd because the Würzburg School put a lot of emphasis on mental set and imageless thought. Würzburg School The work of the Würzburg School was a milestone in the development of experimental psychology. The School was founded by a group of psychologists led by Oswald Külpe, and it provided an alternative to the structuralism of Edward Titchener and Wilhelm Wundt. Those in the School focused mainly on mental operations such as mental set (Einstellung) and imageless thought. Mental set affects perception and problem solving without the awareness of the individual; it can be CU IDOL SELF LEARNING MATERIAL (SLM)

6 Experimental Psychology triggered by instructions or by experience. Similarly, according to Külpe, imageless thought consists of pure mental acts that do not involve mental images. An example of mental set was provided by William Bryan, an American student working in Külpe’s laboratory. Bryan presented subjects with cards that had nonsense syllables written on them in various colors. The subjects were told to attend to the syllables, and in consequence they did not remember the colors of the nonsense syllables. Such results made people question the validity of introspection as a research tool, and led to a decline of voluntarism and structuralism. The work of the Würzburg School later influenced many Gestalt psychologists, including Max Wertheimer. George Trumbull Ladd Experimental psychology was introduced into the United States by George Trumbull Ladd, who founded Yale University’s psychological laboratory in 1879. In 1887, Ladd published Elements of Physiological Psychology, the first American textbook that extensively discussed experimental psychology. Between Ladd’s founding of the Yale Laboratory and his textbook, the center of experimental psychology in the US shifted to Johns Hopkins University, where George Hall and Charles Sanders Peirce were extending and qualifying Wundt's work. Joseph Jastrow With his student Joseph Jastrow, Charles S. Peirce randomly assigned volunteers to a blinded, repeated-measures design to evaluate their ability to discriminate weights. Peirce’s experiment inspired other researchers in psychology and education, which developed a research tradition of randomized experiments in laboratories and specialized textbooks in the 1800s. The Peirce-Jastrow experiments were conducted as part of Peirce’s pragmatic program to understand human perception; other studies considered perception of light, etc. While Peirce was making advances in experimental psychology and psychophysics, he was also developing a theory of statistical inference, which was published in “Illustrations of the Logic of Science” (1877-78) and “A Theory of Probable Inference”; both publications that emphasized the importance of randomization-based inference in statistics. To Peirce and to experimental psychology belongs the honor of having invented randomized experiments, decades before the innovations of Jerzy Neyman and Ronald Fisher in agriculture. CU IDOL SELF LEARNING MATERIAL (SLM)

Experimental Psychology 7 Peirce’s pragmaticist philosophy also included an extensive theory of mental representations and cognition, which he studied under the name of semiotics. Peirce’s student Joseph Jastrow continued to conduct randomized experiments throughout his distinguished career in experimental psychology, much of which would later be recognized as cognitive psychology. There has been a resurgence of interest in Peirce’s work in cognitive psychology. Another student of Peirce, John Dewey, conducted experiments on human cognition, particularly in schools, as part of his “experimental logic” and “public philosophy”. 20th Century In the middle of the 20th century, behaviorism became a dominant paradigm within psychology, especially in the United States. This led to some neglect of mental phenomena within experimental psychology. In Europe this was less the case, as European psychology was influenced by psychologists such as Sir Frederic Bartlett, Kenneth Craik, W.E. Hick and Donald Broadbent, who focused on topics such as thinking, memory and attention. This laid the foundations for the subsequent development of cognitive psychology. In the latter half of the 20th century, the phrase “experimental psychology” had shifted in meaning due to the expansion of psychology as a discipline and the growth in the size and number of its sub-disciplines. Experimental psychologists use a range of methods and do not confine themselves to a strictly experimental approach, partly because developments in the philosophy of science have affected the exclusive prestige of experimentation. In contrast, an experimental method is now widely used in fields such as developmental and social psychology, which were not previously part of experimental psychology. The phrase continues in use, however, in the titles of a number of well- established, high prestige learned societies and scientific journals, as well as some university courses of study in psychology. CU IDOL SELF LEARNING MATERIAL (SLM)

8 Experimental Psychology 1.5 Understanding Experimental Psychology Experimental psychologists are interested in exploring theoretical questions, often by creating a hypothesis and then setting out to prove or disprove it through experimentation. They study a wide range of behavioral topics among humans and animals, including sensation, perception, attention, memory, cognition and emotion. Experimental psychologists use scientific methods to collect data and perform research. Often, their work builds one study at a time, to a larger finding or conclusion. Some researchers have devoted their entire career to answering one complex research question. These psychologists work in a variety of settings, including universities, research centers, government agencies and private businesses. The focus of their research is as varied as the settings in which they work. Often, personal interest and educational background will influence the research questions they choose to explore. In a sense, all psychologists can be considered experimental psychologists since research is the foundation of the discipline, and many psychologists split their professional focus among research, patient care, teaching or program administration. Experimental psychologists, however, often devote their full attention to research its design, execution, analysis and dissemination. Those focusing their careers specifically on experimental psychology contribute work across subfields. For example, they use scientific research to provide insights that improve teaching and learning, create safer workplaces and transportation systems, improve substance abuse treatment programs and promote healthy child development. Experimental psychologists use basic and applied research to explore questions about human and animal behavior. They often use their scientific findings to provide insights that create safer workplaces and transportation systems, improve teaching and learning methods, promote healthy child development and improve substance abuse treatment programs, to list a few examples. Experimental psychologists use scientific methods to collect data and perform research. They can work in varied settings, including universities, research centers, the government and private CU IDOL SELF LEARNING MATERIAL (SLM)

Experimental Psychology 9 businesses. The exact type of research an experimental psychologist performs may depend on a number of factors, including his or her educational background, interests and area of employment. Often, psychologists with training in experimental psychology contribute across subfields, using scientific research to provide insights that improve teaching and learning, create safer workplaces, and promote healthy child development, to list a few examples. 1.6 Experimental Method Design Various experimental methods of design are as follows: 1. Lab Experiments Lab experiments are very common in psychology because they allow experimenters more control over the variables. These experiments can also be easier for other researchers to replicate. The problem, of course, is that what takes place in a lab is not always identical to what takes place in the real world. 2. Field Experiments Sometimes researchers might opt to conduct their experiments in the field. For example, let’s imagine that a social psychologist is interested in researching prosocial behavior. The experimenter might have a person pretend to faint and observe to see how long it takes onlookers to respond. This type of experiment can be a great way to see behavior in action in realistic settings. However, it makes it more difficult for the researchers to control the variables and can introduce confounding variables that might influence the results. 3. Quasi-Experiments While lab and field experiments represent what is known as true experiments, researchers can also utilize a third type known as a quasi-experiment. These are often referred to as natural experiments because the researchers do not have true control over the independent variable. Instead, the treatment level is determined by the natural conditions of the situation. A researcher looking at personality differences and birth order, for example, is not able to manipulate the independent variable in the situation. Treatment levels cannot be randomly assigned because the participants naturally fall into pre-existing groups based on their birth order in their families. CU IDOL SELF LEARNING MATERIAL (SLM)

10 Experimental Psychology 4. Empirical Design Empirical method is meant as the collection of a large amount of data on which to base a theory or derive a conclusion in science. It is part of the scientific method, but is often mistakenly assumed to be synonymous with the experimental method. The empirical method is not sharply defined and is often contrasted with the precision of the experimental method, where data are derived from the systematic manipulation of variables in an experiment. Some of the difficulty in discussing the empirical method is from the ambiguity of the meaning of its linguist root: empiric. Steps for Conducting Empirical Design Since empirical research is based on observation and capturing experiences, it is important to plan the steps to conduct the experiment and how to analyze it. This will enable the researcher to resolve problems or obstacles which can occur during the experiment. Step-1: Define the purpose of the research This is the step where the researcher has to answer questions like: What exactly do want to find out? What is the problem statement?Are there any issues in terms of the availability of knowledge, data, time or resources? Will this research be more beneficial than what it will cost? Step-2: Supporting theories and relevant literature The researcher needs to find out if there are theories which can be linked to his research problem. He has to figure out if any theory can help him support his findings. All kind of relevant literature will help the researcher to find if there are others who have researched this before, or what are the problems faced during this research. The researcher will also have to set up assumptions and also find out if there is any history regarding his research problem Step-3: Creation of hypothesis and measurement Before beginning the actual research he needs to provide himself a working hypothesis or guess what will be the probable result. Researcher has to set up variables, decide the environment for the research and find out how he can relate between the variables. CU IDOL SELF LEARNING MATERIAL (SLM)

Experimental Psychology 11 Step-4: Methodology, research design and data collection In this step, the researcher has to define a strategy for conducting his research. He has to set up experiments to collect data which will enable him to propose the hypothesis. The researcher will decide whether he will need experimental or non-experimental method for conducting the research. The type of research design will vary depending on the field in which the research is being conducted. Step-5: Data analysis and result Data analysis can be done in two ways, qualitatively and quantitatively. Researcher will need to find out what qualitative method or quantitative method will be needed or will he need a combination of both. Depending on the analysis of his data, he will know if his hypothesis is supported or rejected. Analyzing this data is the most important part to support his hypothesis. Step-6: Conclusion A report will need to be made with the findings of the research. The researcher can give the theories and literature that support his research. He can make suggestions or recommendations for further research on his topic. 1.7 Design of Experiments Sound methodology is essential to the study of complex behavioral and mental processes, and this implies, especially, the careful definition and control of experimental variables. As a scientific endeavor, experimental psychology shares several assumptions with most other sciences. Among these are the following: 1. Empiricism Perhaps, the most basic assumption of science is that factual statements about the world must ultimately be based on observations of the world. This notion of empiricism requires that hypotheses and theories be tested against observations of the natural world rather than on a priori reasoning, intuition, or revelation. CU IDOL SELF LEARNING MATERIAL (SLM)

12 Experimental Psychology 2. Testability Closely related to empiricism is the idea that, to be useful, a scientific law or theory must be testable with available research methods. If a theory cannot be tested in any conceivable way, then many scientists consider the theory to be meaningless. Testability implies falsifiability, which is the idea that some set of observations could prove the theory to be incorrect. Testability has been emphasized in psychology because influential or well-known theories like those of Freud have been difficult to test. 3. Determinism Experimental psychologists, like most scientists, accept the notion of determinism. This is the assumption that any state of an object or event is determined by prior states. In other words, behavioral or mental phenomena are typically stated in terms of cause and effect. If a phenomenon is sufficiently general and widely confirmed, it may be called a “law”; psychological theories serve to organize and integrate laws. 4. Parsimony Another guiding idea of science is parsimony, the search for simplicity. For example, most scientists agree that if two theories handle a set of empirical observations equally well, we should prefer the simpler or more parsimonious of the two. A notable early argument for parsimony was stated by the medieval English philosopher William of Occam, and for this reason the principle of parsimony is often referred to as Occam's razor. 5. Operational definition Some well-known behaviorists such as Edward C. Tolman and Clark Hull popularized the idea of operationism, or operational definition. Operational definition implies that a concept be defined in terms of concrete, observable procedures. Experimental psychologists attempt to define currently unobservable phenomena, such as mental events, by connecting them to observations by chains of reasoning. CU IDOL SELF LEARNING MATERIAL (SLM)

Experimental Psychology 13 6. Experiments In experiments, human participants often respond to visual, auditory or other stimuli, following instructions given by an experimenter; animals may be similarly “instructed” by rewarding appropriate responses. Since the 1990s, computers have commonly been used to automate stimulus presentation and behavioral measurement in the laboratory. Behavioral experiments with both humans and animals typically measure reaction time, choices among two or more alternatives, and/or response rate or strength; they may also record movements, facial expressions, or other behaviors. Experiments with humans may also obtain written responses before, during, and after experimental procedures. Control of extraneous variables, minimizing the potential for experimenter bias, counterbalancing the order of experimental tasks, adequate sample size, the use of operational definitions, emphasis on both the reliability and validity of results, and proper statistical analysis are central to experimental methods in psychology. Because an understanding of these matters is important to the interpretation of data in almost all fields of psychology, undergraduate programs in psychology usually include mandatory courses in research methods and statistics. A crucial experiment is an experiment that is intended to test several hypotheses at the same time. Ideally, one hypothesis may be confirmed and all the others rejected. However, the data may also be consistent with several hypotheses, a result that calls for further research to narrow down the possibilities. A pilot study may be run before a major experiment, in order to try out different procedures, determining optimal values of the experimental variables, or uncovering weaknesses in experimental design. The pilot study may not be an experiment as usually defined; it might, for example, consist simply of self-reports. In a field experiment, participants are observed in a naturalistic setting outside the laboratory. Field experiments differ from field studies in that some part of the environment (field) is manipulated in a controlled way (for example, researchers give different kinds of toys to two different groups of children in a nursery school). Control is typically more lax than it would be in a laboratory setting. Other methods of research such as case study, interview, opinion polls and naturalistic observation, are often used by psychologists. These are not experimental methods, as they lack such aspects as well-defined, controlled variables, randomization, and isolation from unwanted variables. CU IDOL SELF LEARNING MATERIAL (SLM)

14 Experimental Psychology 7. Reliability Reliability measures the consistency or repeatability of an observation. For example, one way to assess reliability is the “test-retest” method, done by measuring a group of participants at one time and then testing them a second time to see if the results are consistent. Because the first test itself may alter the results of a second test, other methods are often used. For example, in the “split- half” measure, a group of participants is divided at random into two comparable sub-groups, and reliability is measured by comparing the test results from these groups, It is important to note that a reliable measure need not yield a valid conclusion. 8. Validity Validity measures the relative accuracy or correctness of conclusions drawn from a study. To determine the validity of a measurement quantitatively, it must be compared with a criterion. For example, to determine the validity of a test of academic ability, that test might be given to a group of students and the results correlated with the grade-point averages of the individuals in that group. As this example suggests, there is often controversy in the selection of appropriate criteria for a given measure. In addition, a conclusion can only be valid to the extent that the observations upon which it is based are reliable. 9. Internal validity Internal validity refers to the extent to which a set of research findings provides compelling information about causality. High internal validity implies that the experimental design of a study excludes extraneous influences, such that one can confidently conclude that variations in the independent variable caused any observed changes in the dependent variable. 10. External Validity External Validity refers to the extent to which the outcome of an experiment can be generalized to apply to other situations than those of the experiment - for example, to other people, other physical or social environments, or even other cultures. 11. Construct Validity Construct validity refers to the extent to which the independent and dependent variables in a study represent the abstract hypothetical variables of interest. In other words, it has to do with CU IDOL SELF LEARNING MATERIAL (SLM)

Experimental Psychology 15 whether the manipulated and/or measured variables in a study accurately reflect the variables the researcher hoped to manipulate. Construct validity also reflects the quality of one’s operational definitions. If a researcher has done a good job of converting the abstract to the observable, construct validity is high. 12. Conceptual validity Conceptual validity refers to how well specific research maps onto the broader theory that it was designed to test. Conceptual and construct validity have a lot in common, but conceptual validity relates a study to broad theoretical issues whereas construct validity has more to do with specific manipulations and measures. 1.8 Scales of Measurement for Psychological Experiments Measurement can be defined as “the assignment of numerals to objects or events according to rules.” Almost all psychological experiments involve some sort of measurement, if only to determine the reliability and validity of results, and of course measurement is essential if results are to be relevant to quantitative theories. The rule for assigning numbers to a property of an object or event is called a “scale”. Following are the basic scales used in psychological measurement. 1. Nominal Measurement In a nominal scale, numbers are used simply as labels – a letter or name would do as well. Examples are the numbers on the shirts of football or baseball players. The labels are more useful if the same label can be given to more than one thing, meaning that the things are equal in some way, and can be classified together. 2. Ordinal Measurement An ordinal scale arises from the ordering or ranking objects, so that A is greater than B, B is greater than C, and so on. Many psychological experiments yield numbers of this sort; for example, a participant might be able to rank odors such that A is more pleasant than B, and B is more pleasant than C, but these rankings (“1, 2, 3, ...”) would not tell by how much each odor differed from another. Some statistics can be computed from ordinal measures for example, median, percentile, and order correlation – but others, such as standard deviation, cannot properly be used. CU IDOL SELF LEARNING MATERIAL (SLM)

16 Experimental Psychology 3. Interval Measurement An interval scale is constructed by determining the equality of differences between the things measured. That is, numbers form an interval scale when the differences between the numbers correspond to differences between the properties measured. For instance, one can say that the difference between 5 and 10 degrees on a Fahrenheit thermometer equals the difference between 25 and 30, but it is meaningless to say that something with a temperature of 20 degrees Fahrenheit is “twice as hot” as something with a temperature of 10 degrees. (Such ratios are meaningful on an absolute temperature scale such as the Kelvin scale. See next section.) “Standard scores” on an achievement test are said to be measurements on an interval scale, but this is difficult to prove. 4. Ratio Measurement A ratio scale is constructed by determining the equality of ratios. For example, if, on a balance instrument, object A balances two identical objects B, then one can say that A is twice as heavy as B and can give them appropriate numbers, for example “A weighs 2 grams” and “B weighs 1 gram”. A key idea is that such ratios remain the same regardless of the scale units used; for example, the ratio of A to B remains the same whether grams or ounces are used. Length, resistance, and Kelvin temperature are other things that can be measured on ratio scales. Some psychological properties such as the loudness of a sound can be measured on a ratio scale. 5. Research Design The simplest experimental design is a one-way design, in which there is only one independent variable. The simplest kind of one-way design involves just two-groups, each of which receives one value of the independent variable. A two-group design typically consists of an experimental group (a group that receives treatment) and a control group (a group that does not receive treatment). The one-way design may be expanded to a one-way, multiple groups design. Here, a single independent variable takes on three or more levels. This type of design is particularly useful because it can help to outline a functional relationship between the independent and dependent variables. CU IDOL SELF LEARNING MATERIAL (SLM)

Experimental Psychology 17 Types of Research Design (i) Exploratory Research Design A marketing research study may be either exploratory or full scale. Exploratory research is conducted when the researcher does not know how and why certain phenomenon occurs. Here, the hypothetical solutions or actions are explored and evaluated by the decision-maker, e.g., evaluation of quality of service of a bank/hotel/airline. Here, the quality cannot be accessed directly as tangible features are not available. (ii) Conclusive Research Design Conclusive Research Design is typically more formal and structured than exploratory research. It is based on large representative samples, and the Market Information obtained is subjected to quantitative analysis. Conclusive Research is designed to assist the decision maker in determining, evaluating and selecting the best course of action to take in a given situation. As shown in the figure conclusive research designs may be either descriptive or causal and descriptive designs may be either cross-sectional or longitudinal. (a) Descriptive Research: Descriptive research is undertaken when the researcher desires to know the characteristics of certain groups such as age, sex, occupation, income or education. The objective of descriptive research is to answer the “who, what, when, where and how” of the subject under study/investigation. (b) Casual Research: Casual research design is the third type of research design. As the name indicates, casual design investigates the cause and effect relationship between two or more variables. This design measures the extent of relationship between the variables. Casual research designs attempt to specify the nature of functional relationship between two or more variables. 6. Factorial Designs One-way designs are limited in that they allow researchers to look at only one independent variable at a time, whereas many phenomena of interest are dependent on multiple variables. Because CU IDOL SELF LEARNING MATERIAL (SLM)

18 Experimental Psychology of this, R.A Fisher popularized the use of factorial designs. Factorial designs contain two or more independent variables that are completely “crossed,” which means that every level each independent variable appears in combination with every level of all other independent variables. Factorial designs carry labels that specify the number of independent variables and the number of levels of each independent variable there are in the design. For example, a 2 × 3 factorial design has two independent variables (because there are two numbers in the description), the first variable having two levels and the second having three. 7. Main Effects and Interactions The effects of independent variables in factorial studies, taken singly, are referred to as main effects. This refers to the overall effect of an independent variable, averaging across all levels of the other independent variables. A main effect is the only effect detectable in a one-way design. Often more important than main effects are “interactions”, which occur when the effect of one independent variable on a dependent variable depends on the level of a second independent variable. For example, the ability to catch a ball (dependent variable) might depend on the interaction of visual acuity and the size of the ball being caught. A person with good eyesight might catch a small ball most easily, and person with very poor eyesight might do better with a large ball, so the two variables can be said to interact. 8. Within- and Between-subjects Designs Two basic approaches to research design are within-subjects design and between-subjects design. In within-subjects or repeated measures designs, each participant serves in more than one or perhaps all of the conditions of a study. In between-subjects designs, each participant serves in only one condition of an experiment. Within-subjects designs have significant advantages over between- subjects designs, especially when it comes to complex factorial designs that have many conditions. In particular, within-subjects designs eliminate person confounds, i.e., they get rid of effects caused by differences among subjects that are irrelevant to the phenomenon under study. However, the within-subject design has the serious disadvantage of possible sequence effects. Because each participant serves in more than one condition, the passage of time or the performance of an earlier CU IDOL SELF LEARNING MATERIAL (SLM)

Experimental Psychology 19 task may affect the performance of a later task. For example, a participant might learn something from the first task that affects the second. 1.9 Experimental Instruments Instruments used in experimental psychology evolved along with technical advances and with the shifting demands of experiments. The earliest instruments, such as the Hipp Chronoscope and the kymograph, were originally used for other purposes. The list below exemplifies some of the different instruments used over the years. Hipp Chronoscope/Chronograph This instrument, invented by Matthäus Hipp around 1850, uses a vibrating reed to tick off time in 1000ths of a second. Originally designed for experiments in physics, it was later adapted to study the speed of bullets. After then being introduced to physiology, it was finally used in psychology to measure reaction time and the duration of mental processes. Stereoscope The first stereoscope was invented by Wheatstone in 1838. It presents two slightly different images, one to each eye, at the same time. Typically, the images are photographs of the same object taken from camera positions that mimic the position and separation of the eyes in the head. When one looks through the stereoscope, the photos fuse into a single image that conveys a powerful sense of depth and solidity. Kymograph Developed by Carl Ludwig in the 19th century, the kymograph is a revolving drum on which a moving stylus tracks the size of some measurement as a function of time. The kymograph is similar to the polygraph, which has a strip of paper moving under one or more pens. The kymograph was originally used to measure blood pressure and it later was used to measure muscle contractions and speech sounds. In psychology, it was often used to record response times. CU IDOL SELF LEARNING MATERIAL (SLM)

20 Experimental Psychology Photokymographs This device is a photographic recorder. It used mirrors and light to record the photos. Inside a small box with a slit for light there are two drive rollers with film connecting the two. The light enters through the slit to record on the film. Some photokymographs have a lens so an appropriate speed for the film can be reached. Galvanometer The galvanometer is an early instrument used to measure the strength of an electric current. Hermann von Helmholtz used it to detect the electrical signals generated by nerve impulses, and thus to measure the time taken by impulses to travel between two points on a nerve. Audiometer This apparatus was designed to produce several fixed frequencies at different levels of intensity. It could either deliver the tone to a subject's ear or transmit sound oscillations to the skull. An experimenter would generally use an audiometer to find the auditory threshold of a subject. The data received from an audiometer is called an audiogram. Colorimeters These determine the color composition by measuring its tricolor characteristics or matching of a color sample. This type of device would be used in visual experiments. Algesiometers and Algometers Both of these are mechanical stimulations of pain. They have a sharp needle-like stimulus point so it does not give the sensation of pressure. Experimenters use these when doing an experiment on analgesia. Olfactometer An olfactometer is any device that is used to measure the sense of smell. The most basic type in early studies was placing a subject in a room containing a specific measured amount of an odorous CU IDOL SELF LEARNING MATERIAL (SLM)

Experimental Psychology 21 substance. More intricate devices involve some form of sniffing device, such as the neck of a bottle. The most common olfactometer found in psychology laboratories at one point was the Zwaardemker olfactometer. It had two glass nasal tubes projecting through a screen. One end would be inserted into a stimulus chamber, the other end is inserted directly into the nostrils. Mazes Probably one of the oldest instruments for studying memory would be the maze. The common goal is to get from point A to point B, however the mazes can vary in size and complexity. Two types of mazes commonly used with rats are the radial arm maze and the Morris water maze. The radial arm maze consists of multiple arms radiating from a central point. Each arm has a small piece of food at the end. The Morris water maze is meant to test spatial learning. It uses a large round pool of water that is made opaque. The rat must swim around until it finds the escape platform that is hidden from view just below the surface of the water. Electroencephalograph (EEG) The EEG is an instrument that can reflect the summed electrical activity of neural cell assemblies in the brain. It was originally used as an attempt to improve medical diagnoses. Later, it became a key instrument to psychologists in examining brain activity and it remains a key instrument used in the field today. Functional Magnetic Resonance Imaging (fMRI) The fMRI is an instrument that can detect changes in blood oxygen levels over time. The increase in blood oxygen levels shows where brain activity occurs. These are rather bulky and expensive instruments which are generally found in hospitals. They are most commonly used for cognitive experiments. Positron Emission Tomography (PET) PET is also used to look at brain activity. It can detect drugs binding neurotransmitter receptors in the brain. A down side to PET is that it requires radioisotopes to be injected into the body so the CU IDOL SELF LEARNING MATERIAL (SLM)

22 Experimental Psychology brain activity can be mapped out. The radioisotopes decay quickly so they do not accumulate in the body. The use of experimental methods was perhaps the main characteristic by which psychology became distinguishable from philosophy in the late 19th century. Ever since then experiments have been an integral part of most psychological research. Following is a sample of some major areas that use experimental methods. Cognitive Psychology Some of the major topics studied by cognitive psychologists are memory, learning, problem solving, and attention. Most cognitive experiments are done in a lab instead of a social setting; this is done mainly to provide maximum control of experimental variables and minimal interference from irrelevant events and other aspects of the situation. A great many experimental methods are used; frequently used methods are described on the main pages of the topics just listed. In addition to studying behavior, experimenters may use fMRI or PET so they are able to see what areas of the brain are active during cognitive processing. Animal Cognition Animal cognition refers to the mental capacities of non-human animals, and research in this field often focuses on matters similar to those of interest to cognitive psychologists using human participants. Cognitive studies using animals can often control conditions more closely and use methods not open to research with humans. In addition, processes such as conditioning my appear in simpler form in animals, certain animals display unique capacities (such as echo location in bats) that clarify important cognitive functions, and animal studies often have important implications for the survival and evolution of species. Sensation and Perception Experimenters typically manipulate stimuli affecting vision, hearing, touch, smell, taste and proprioception. Sensory measurement plays a large role in the field, covering many aspects of sensory performance – for example, minimum discriminable differences in brightness or the detection of odors; such measurement involves the use of instruments such as the oscillator, attenuator, CU IDOL SELF LEARNING MATERIAL (SLM)

Experimental Psychology 23 stroboscope, and many others listed earlier in this article. Experiments also probe subtle phenomena such as visual illusions, or the emotions aroused by stimuli of different sorts. Behavioral Psychology The behavioristic approach to psychology reached its peak of popularity in the mid twentieth century but still underlies much experimental research and clinical application. Its founders include such figures as Ivan Pavlov, John B. Watson, and B.F. Skinner. Pavlov’s experimental study of the digestive system in dogs led to extensive experiments through which he established the basic principles of classical conditioning. Watson popularized the behaviorist approach to human behavior; his experiments with Little Albert are particularly well known. Skinner distinguished operant conditioning from classical conditioning and established the experimental analysis of behavior as a major component in the subsequent development of experimental psychology. Social Psychology Social psychologists use experimental methods, both within and outside the laboratory, in an attempt to understand human social interaction. Two widely cited experiments in social psychology experiment are the Stanford prison experiment conducted by Philip Zimbardo in 1971 and the Milgram obedience experiment by Stanley Milgram. In both experiments, ordinary individuals were induced to engage in remarkably cruel behavior, suggesting that such behavior can be very strongly influenced by social pressure. Because of possible negative effects on the participants, neither of these experiments could be legally performed in the United States today. 1.10 Summary Experimental psychology examines relationships between human behavior and the mind. Experimental psychology is centered on fact-based, scientific research and experimentation. Therefore, experimental psychologists manipulate research variables in order to discover relationships between cognition and behavior. Experimental psychology explores basic concepts, such as memory and motivation, in many areas, such as child, social and educational psychology.Almost all Experimental CU IDOL SELF LEARNING MATERIAL (SLM)

24 Experimental Psychology psychology work is conducted in controlled environments, such as university research labs. While every branch of psychology strives to understand human behavior and thought, experimental psychology solely focuses on controlled experiments with designated variables, test subjects and statistical results. Experimental psychology refers to work done by those who apply experimental methods to psychological study and the processes that underlie it. Experimental psychologists employ human participants and animal subjects to study a great many topics, including sensation and perception, memory, cognition, learning, motivation, emotion; developmental processes, social psychology, and the neural substrates of all of these. Charles Bell was a British physiologist, whose main contribution was research involving the nervous system. He wrote a pamphlet summarizing his research on rabbits. His research concluded that sensory nerves enter at the posterior (dorsal) roots of the spinal cord and motor nerves emerge from the anterior (ventral) roots of the spinal cord. Eleven years later, a French physiologist Francois Magendie published the same findings without being aware of Bell's research. Due to Bell not publishing his research, this discovery was called the Bell-Magendie law. Bell's discovery disproved the belief that nerves transmitted either vibrations or spirits. Weber was a German physician who is credited with being one of the founders of experimental psychology. Weber’s main interests were the sense of touch and kinesthesis. His most memorable contribution to the field of experimental psychology is the suggestion that judgments of sensory differences are relative and not absolute. This relativity is expressed in “Weber’s Law,” which suggests that the just-noticeable difference, or jnd is a constant proportion of the ongoing stimulus level. Weber’s Law is stated as an equation: Fechner published in 1860 what is considered to be the first work of experimental psychology, “Elemente der Psychophysik.” Some historians date the beginning of experimental psychology from the publication of “Elemente.” Weber was not a psychologist, and it was Fechner who realized the importance of Weber’s research to psychology. Fechner was profoundly interested in establishing a scientific study of the mind-body relationship, which became known as psychophysics. Much of Fechner’s research focused on the measurement of psychophysical thresholds and just noticeable CU IDOL SELF LEARNING MATERIAL (SLM)

Experimental Psychology 25 differences, and he invented the psychophysical method of limits, the method of constant stimuli, and the method of adjustment, which are still in use. Oswald Külpe is the main founder of the Würzburg School in Germany. He was a pupil of Wilhelm Wundt for about twelve years. Unlike Wundt, Külpe believed experiments were possible to test higher mental processes. In 1883, he wrote Grundriss der Psychologie, which had strictly scientific facts and no mention of thought. The lack of thought in his book is odd because the Würzburg School put a lot of emphasis on mental set and imageless thought. The work of the Würzburg School was a milestone in the development of experimental psychology. The School was founded by a group of psychologists led by Oswald Külpe, and it provided an alternative to the structuralism of Edward Titchener and Wilhelm Wundt. Those in the School focused mainly on mental operations such as mental set (Einstellung) and imageless thought. Mental set affects perception and problem solving without the awareness of the individual; it can be triggered by instructions or by experience. Experimental psychology was introduced into the United States by George Trumbull Ladd, who founded Yale University’s psychological laboratory in 1879. In 1887, Ladd published Elements of Physiological Psychology, the first American textbook that extensively discussed experimental psychology. Between Ladd’s founding of the Yale Laboratory and his textbook, the center of experimental psychology in the US shifted to Johns Hopkins University, where George Hall and Charles Sanders Peirce were extending and qualifying Wundt’s work. Experimental psychologists are interested in exploring theoretical questions, often by creating a hypothesis and then setting out to prove or disprove it through experimentation. They study a wide range of behavioral topics among humans and animals, including sensation, perception, attention, memory, cognition and emotion. Lab experiments are very common in psychology because they allow experimenters more control over the variables. These experiments can also be easier for other researchers to replicate. The problem, of course, is that what takes place in a lab is not always identical to what takes place in the real world. CU IDOL SELF LEARNING MATERIAL (SLM)

26 Experimental Psychology Sometimes researchers might opt to conduct their experiments in the field. For example, let’s imagine that a social psychologist is interested in researching prosocial behavior. The experimenter might have a person pretend to faint and observe to see how long it takes onlookers to respond. This type of experiment can be a great way to see behavior in action in realistic settings. However, it makes it more difficult for the researchers to control the variables and can introduce confounding variables that might influence the results. While lab and field experiments represent what is known as true experiments, researchers can also utilize a third type known as a quasi-experiment. These are often referred to as natural experiments because the researchers do not have true control over the independent variable. Instead, the treatment level is determined by the natural conditions of the situation. A researcher looking at personality differences and birth order, for example, is not able to manipulate the independent variable in the situation. Treatment levels cannot be randomly assigned because the participants naturally fall into pre-existing groups based on their birth order in their families. Sound methodology is essential to the study of complex behavioral and mental processes, and this implies, especially, the careful definition and control of experimental variables. As a scientific endeavor, experimental psychology shares several assumptions with most other sciences. Perhaps, the most basic assumption of science is that factual statements about the world must ultimately be based on observations of the world. This notion of empiricism requires that hypotheses and theories be tested against observations of the natural world rather than on a priori reasoning, intuition, or revelation. Closely related to empiricism is the idea that, to be useful, a scientific law or theory must be testable with available research methods. If a theory cannot be tested in any conceivable way, then many scientists consider the theory to be meaningless. Testability implies falsifiability, which is the idea that some set of observations could prove the theory to be incorrect. Testability has been emphasized in psychology because influential or well-known theories like those of Freud have been difficult to test. Animal cognition refers to the mental capacities of non-human animals, and research in this field often focuses on matters similar to those of interest to cognitive psychologists using human participants. Cognitive studies using animals can often control conditions more closely and use methods CU IDOL SELF LEARNING MATERIAL (SLM)

Experimental Psychology 27 not open to research with humans. In addition, processes such as conditioning my appear in simpler form in animals, certain animals display unique capacities (such as echo location in bats) that clarify important cognitive functions, and animal studies often have important implications for the survival and evolution of species. Experimental psychologists, like most scientists, accept the notion of determinism. This is the assumption that any state of an object or event is determined by prior states. In other words, behavioral or mental phenomena are typically stated in terms of cause and effect. If a phenomenon is sufficiently general and widely confirmed, it may be called a “law”; psychological theories serve to organize and integrate laws. In experiments, human participants often respond to visual, auditory or other stimuli, following instructions given by an experimenter; animals may be similarly “instructed” by rewarding appropriate responses. Since the 1990s, computers have commonly been used to automate stimulus presentation and behavioral measurement in the laboratory. Behavioral experiments with both humans and animals typically measure reaction time, choices among two or more alternatives, and/or response rate or strength; they may also record movements, facial expressions, or other behaviors. Experiments with humans may also obtain written responses before, during, and after experimental procedures. 1.11 Key Words/Abbreviations  Experimental Psychology: Experimental psychology examines relationships between human behavior and the mind.  Experimental Method Design: Lab experiments are very common in psychology.  Design of Experiments: Sound methodology is essential to the study of complex behavioral and mental processes.  Scales of Measurement: Measurement can be defined as “the assignment of numerals to objects or events according to rules.”  Experimental Instruments - Instruments used in experimental psychology evolved along with technical advances and with the shifting demands of experiments. CU IDOL SELF LEARNING MATERIAL (SLM)

28 Experimental Psychology 1.12 Learning Activity 1. You are required to prepare origin and history of Experimental Psychology. _________________________________________________________________ _________________________________________________________________ 2. You are suggested to identify the applications of Experimental Method Design. ________________________________________________________________ _________________________________________________________________ 3. You are required to prepare the report of “Scales of measurement for psychological experiments”. ________________________________________________________________ _________________________________________________________________ 1.13 Unit End Exercises (MCQs and Descriptive) A. Descriptive Type Questions 1. Give the meaning of Experimental Psychology. 2. Discuss the nature of Experimental Psychology. 3. Explain in brief about history of Experimental Psychology. 4. Discuss in details about the understanding Experimental Psychology. 5. Explain in details about the Experimental Methods Design. 6. What is Design of Experiment? Discuss the applications of Experimental Method Design. 7. Explain about scales of measurement for psychological experiments. 8. Discuss in details about Experimental Instruments. CU IDOL SELF LEARNING MATERIAL (SLM)

Experimental Psychology 29 B. Multiple Choice Questions 1. Which of the following examines relationships between human behavior and the mind? (a) Expatriation (b) Experimental psychology (c) Cognitive conditioning (d) All the above 2. Experimental psychologists employ human participants and animal subjects to study a great many topics including __________. (a) Sensation and perception (b) Memory and cognition (c) Learning and motivation (d) All the above 3. Which of the following consider as the nature of Experimental Psychology? (a) Experimental psychology is important because the findings discovered by psychologists play a vital role in our understanding of the human mind and behavior. (b) Experimental psychology is the scientific and empirical approach to the study of the mind. (c) The experimental approach means that tests are administered to participants, with both control and experimental conditions. (d) All the above 4. Which of the following is not the experimental psychologist? (a) Hermann Ebbinghaus (b) Edward Titchener (c) Philip Kotlar (d) Charles Bell CU IDOL SELF LEARNING MATERIAL (SLM)

30 Experimental Psychology 5. Which of the following is not the Experimental Method Design? (a) Lab Experiment (b) Field Experiment (c) Quasi-Experiment (d) Descriptive Experiment Answers: 1. (b), 2. (d), 3. (b), 4. (c), 5. (d) 1.14 References References of this unit have been given at the end of the book.  CU IDOL SELF LEARNING MATERIAL (SLM)

Contribution of Weber, Fechner, Wundt and Galton 31 UNIT 2 CONTRIBUTION OF WEBER, FECHNER, WUNDTAND GALTON Structure: 2.0 Learning Objectives 2.1 Introduction 2.2 Ernst Heinrich Weber 2.3 Contribution of Weber 2.4 Gustav Theodor Fechner 2.5 Contribution of Fechner 2.6 Wilhelm Wundt 2.7 Contribution of Wundt 2.8 Sir Francis Galton 2.9 Contribution of Galton 2.10 Summary 2.11 Key Words/Abbreviations 2.12 LearningActivity 2.13 Unit End Exercises (MCQs and Descriptive) 2.14 References CU IDOL SELF LEARNING MATERIAL (SLM)

32 Experimental Psychology 2.0 Learning Objectives After studying this unit, you will be able to:  Elaborate the viewpoints of psychologists and physiologists  Explain the Wilhelm Wundt 2.1 Introduction Weber’s law is important psychological law quantifying the perception of change in a given stimulus. The law states that the change in a stimulus that will be just noticeable is a constant ratio of the original stimulus. It has been shown not to hold for extremes of stimulation. The law was originally postulated to describe researches on weight lifting by the German physiologist Ernst Heinrich Weber in 1834 and was later applied to the measurement of sensation by Weber’s student Gustav Theodor Fechner, who went on to develop from the law the science of psychophysics. By stating a relationship between the spiritual and physical worlds, the law indicated to Fechner that there is really only one world, the spiritual. To others, the law meant the possibility of a scientific, quantitative psychology. The combined work of Weber and Fechner has been useful, especially in hearing and vision research, and has had an impact on attitude scaling and other testing and theoretical developments. 2.2 Ernst Heinrich Weber Ernst Heinrich Weber, German anatomist and physiologist whose fundamental studies of the sense of touch introduced a concept that of the just noticeable difference, the smallest difference perceivable between two similar stimuli that is important to psychology and sensory physiology. Similar observations were made on other senses, including sight and hearing. He formulated the Weber’s law: (ΔI/I = k – constant), CU IDOL SELF LEARNING MATERIAL (SLM)

Contribution of Weber, Fechner, Wundt and Galton 33 where, I is the original intensity of stimulation, ΔI is the addition to it required for the difference to be perceived, and k is a constant is known as Weber’s constant. For lifting weights, the ratio was one to 40. That is, for any standard unit of 40, subjects would notice a difference if one more unit were added to the weight. The constant is different for each sense (for intensity of light – 1/100, sound – 1/10). Weber also described an absolute threshold for all senses, is the smallest detectable level of a stimulus. The eldest of three brothers, all of whom achieved scientific distinction, Weber was a professor at the University of Leipzig from 1818 until 1871. Though he conducted many anatomical investigations, he is known chiefly for his work on sensory response to weight, temperature, and pressure; he described a number of his experiments in this area in De Tactu. Weber determined that there was a threshold of sensation that must be passed before an increase in the intensity of any stimulus could be detected; the amount of increase necessary to create sensation was the just-noticeable difference. He further observed that the difference was a ratio of the total intensity of sensation, rather than an absolute figure; thus, a greater weight must be added to a 100-pound load than to a 10-pound load for a man carrying the load to notice the change. Similar observations were made on other senses, including sight and hearing. Weber also described a terminal threshold for all senses, the maximum stimulus beyond which no further sensation could be registered. CU IDOL SELF LEARNING MATERIAL (SLM)

34 Experimental Psychology Fig. 2.1: Ernst Heinrich Weber Early Life Ernst Heinrich Weber was born on 24 June 1795 in Wittenberg, Saxony, Holy Roman Empire. He was son to Michael Weber, a Professor of Theology at the University of Wittenberg. At a young age, Weber became interested in physics and the sciences after being heavily influenced by Ernst Chladni, a physicist often referred to as the “Father of Acoustics”. Weber completed secondary school at Meissen and began studying medicine at the University of Wittenberg in 1811. He went on to receive his MD in 1815 from the University of Leipzig. The fighting and the aftermath of the Napoleonic wars forced Weber to relocate from Wittenberg. He became an assistant in J.C. Clarus’ medical clinic in Leipzig in 1817 and then a professor in comparative anatomy in 1818 at the University of Leipzig. He became chair of human anatomy at the university in 1821. Ernst Weber’s first direct contribution to psychology came in 1834 when trying to describe the sensation of touch. CU IDOL SELF LEARNING MATERIAL (SLM)

Contribution of Weber, Fechner, Wundt and Galton 35 In 1817, Weber was appointed as the Dozent of Psychology at Leipzig. He moved on to become Professor of Anatomy the following year (1818). He held the position for many years, finally moving to Professor of Psychology towards the end of his life. In his later life, Weber became less involved in testing and experimenting, although he was still interested in sensory physiology. Ernst Heinrich Weber retired from the University of Leipzig in 1871. He continued to work with his brother, Eduard and their work with nerve stimulation and muscle suppression lead to inhibitory responses as a popular therapy of the time. Ernst Weber died in 1878 in Leipzig, Germany. Education: Weber learned Latin in secondary school, and began to study medicine in 1811 at the University of Wittenberg. He received his doctor of medicine degree (MD) from this University in 1815, specializing in comparative anatomy. Influenced by: Johann Christian Rosenmüller, Ernst Chladni Ludwig and Wilhelm Gilbert. Career Highlights: In 1818, he was appointed Associate Professor of comparative anatomy at Leipzig University, where he was made a Fellow Professor of Anatomy and Physiology in 1821. Weber was a professor at the University of Leipzig from 1818 until 1871. In 1821, he was the Chair of Human Anatomy which in 1840 was joined with physiology and in 1865 Chair of Physiology relinquished to Carl Ludwig. Around 1860, Weber worked with Gustav Fechner on psychophysics, during which time he formulated Weber’s Law. Later, Gustav Fechner discovered the law (S = k log R), named the Fechner-Weber law, because it based on the theory advanced earlier by Ernst Heinrich Weber. Personal Life: He devoted his life to science and research. Zest: With his brother Eduard Friedrich Weber, 1806-71, he discovered the inhibitory power of the vagus nerve (1845). With another brother, Wilhelm Eduard Weber, 1804-91, German physicist he made studies of acoustics and wave motion. He wrote (1825) a book on wave motion. Also, his brothers together made a study of walking. CU IDOL SELF LEARNING MATERIAL (SLM)

36 Experimental Psychology Publications In De Tactu, published in English as On Touch: Anatomical and Physiological Notes, Weber proposed there was a threshold of sensation in each individual. The two-point threshold, the smallest distance between two points where a person determines that it is two points and not one, was Weber’s first discovery. Weber’s work made a significant impact on the field of experimental psychology, as he was one of the first scientists to test his ideas on humans. His meticulous notes and new ideas of testing subjects described in his book Der tastsinn und das gemeingefühl (English: “The sense of touch and the common sensibility”) led E.B. Titchener to call the work “the foundation stone of experimental psychology”. The book that described blood circulation research, Wellenlehre auf Experimente gegründet (English: “Wave Theory, Founded on Experiments”) became instantly recognized as very important to physics and physiology. This research lead the way for future investigating, although it was not formally published until 1850 with the culmination of the rest of his research on blood in a book entitled, Ueber die Anwendung der Wellenlehre auf die Lehre vom Kreislauf des Blutes und insbesondere auf die Pulslehre (English: “Concerning the application of the wave theory to the theory of the circulation of the blood and, in particular, on the pulse teaching”). Legacy and Influence Weber is often cited as the pioneer or father of experimental psychology. He was the first to conduct true psychological experiments that held validity. While most psychologists of the time conducted work from behind a desk, Weber was actively conducting experiments, manipulating only one variable at a time in order to gain more accurate results. This paved the way for the field of psychology as an experimental science and opened the way for the development of even more accurate and intense research methods. One of Weber’s greatest influences was on Gustav Fechner. Weber was appointed the Dozent of Psychology at the University of Leipzig the same year that Fechner enrolled. Weber’s work with sensation inspired Fechner to further the work and go on to develop Weber’s law. At the time of his sensation work, Weber did not fully realize the implications that his experiments would have on understanding of sensory stimulus and response. CU IDOL SELF LEARNING MATERIAL (SLM)

Contribution of Weber, Fechner, Wundt and Galton 37 2.3 Contribution of Weber Ernst Weber was a German physiologist and psychologist. He was regarded as a predecessor of experimental psychology and one of the founders of Psychophysics, the branch of psychology that studies the relations between physical stimuli and mental states. He is known chiefly for his work on investigation of subjective sensory response (sensations) to the impact of external physical stimuli: weight, temperature and pressure. Contributions: Weber experimentally determined the accuracy of tactile sensations, namely, the distance between two points on the skin, in which a person can perceive two separate touches. He discovered the two-point threshold – the distance on the skin separating two pointed stimulators that is required to experience two rather than one point of stimulation. In 1834, he conducted research on the lifting of weights. From his researches, he discovered that the experience of differences in the intensity of sensations depends on percentage differences in the stimuli rather than absolute differences. This is known as the just noticeable difference (jnd), difference threshold, or limen. Weber’s works was considered by the English-American psychologist Edward Titchener to be “the foundation stone of experimental psychology.” Especially important was his transfer of experimental methods of physiology in the psychology field. Honors and Awards: Foreign Corresponding Member of the St. Petersburg Academy of Sciences (1869). Another great contribution to the physiology of the blood circulation was the startling discovery by Eduard and Ernst Weber that electrical stimulation of some parts of the brain or of the peripheral end of the vagus nerve slows the action of the heart and can even bring it to a standstill (1845). It was the first instance of nerve action causing inhibition of an autonomic activity, rather than exciting it. It became an important milestone in the evolution of physiology not only for its significance to the circulation but also because its discovery brought to light a hitherto unknown but essential kind of nerve action. The ensuing chain of investigations showed that inhibition is a common phenomenon in CU IDOL SELF LEARNING MATERIAL (SLM)

38 Experimental Psychology the central nervous system and that an adequate balance between excitation and inhibition is indispensable for its normal function. About 1826, Weber began a long series of remarkable systematic studies of sensory functions, especially of the “lower senses,” which had hitherto been one of the most neglected areas of physiology. Physiologists had studied mainly the problems of vision and hearing, which seemed more interesting and promising. In his studies of other physiological problems, Weber, a distinguished anatomist, usually followed function in close relation to structure. In this field, however, there was no anatomical basis because the skin, muscle and visceral receptors were not discovered until later (Meissner, 1852; Krause, 1860). Nonetheless, his physical approach and attempts to determine quantitative relations of the stimulus to its effect, sensation, led to remarkable results despite the very simple methods used in his observations and experiments. An important feature of Weber’s examinations and comparisons was the use of the notion of threshold (although this term was not actually used). He was well aware of the significance of its exactly determined values for estimating and comparing the performance of the skin and other sensory organs. A markedly greater ability to distinguish two very slightly different weights when they are lifted from, rather than when placed on, the hand, is explained by the special muscle sense. Examining the sense of touch in great detail, especially the local sense and differential threshold with a compass, Weber determined the characteristics of sensations of pressure and of temperature positive (warm) and negative (cold)—and stressed the role of adaptation and local differences. Thus, he gave sensory physiology a new orientation toward quantitative approach and methods, bringing into prominence both facts (mostly his own findings) and problems. He not only systematically collected facts but also drew rational conduction about the physiological bases of the observed phenomena He assumed isolated conduction in nerve fibers and formulated theories of projection and objectification. The division of each nerve fiber into a small circle of nerve endings was the background of local discrimination and of differences in its limen as determined by a compass. In using his physical considerations as the basis for examining the differential thresholds of skin and muscle sensations, Weber found that two sensations are just noticeably different as long as the ratio between the strengths in each pair of stimuli remains constant. For instance, the smallest CU IDOL SELF LEARNING MATERIAL (SLM)

Contribution of Weber, Fechner, Wundt and Galton 39 appreciable difference between two weights or lengths (usually called “just noticeable difference” or “Weber fraction”) is a constant fraction of the weights themselves, approximately 1/30 (a just discriminable increment of intensity). It was supposed that Weber’s law was generally valid, but many discussions and criticisms led to the more moderate view that for most modalities it applies only over a limited range of intensities. Nevertheless, Fechner, assuming that discriminable increments are equal units of sensation, derived the formula S = K log I + C, where intensity of sensation (S) is a linear function of the logarithm of intensity of the stimulus (I) and K and C are constants. Fechner’s derivation has been criticized mainly because the stimulus a physical factor can easily be measured, while sensation a subjective impression cannot be expressed in physical terms. Quantitative comparisons became possible, however, when modern electrophysiological methods made it possible to follow the response of single sensory fibers, i.e., the frequency of the messages from a single receptor. Over a certain range of intensities, it is indeed a linear function of the logarithm of the stimulus, as has been shown for the muscle spindle by B.H. Matthews and for the Limulus eye by H.K. Hartline and C.H. Graham. It cannot be stated whether it is fitting for the response of all forms of sense organs, but it seems that Fechner’s equation corresponds to a fundamental feature of sense organ behavior. Weber was the first to draw the attention of physiologists to the skin as the seat of differentiated sense organs directed toward the external world, like other sensory organs, in contrast with the common sensibility (Gemeingefühl) directed toward our own body. His research had many philosophical implications and a great impact on further studies of skin senses and some general problems of sensation by physiologists and psychologists. He began a very fruitful period in the research on senses and is rightly considered as one of the founders of psychophysics. His work on tactile sensations has become classic. CU IDOL SELF LEARNING MATERIAL (SLM)

40 Experimental Psychology 2.4 Gustav Theodor Fechner Gustav Theodor Fechner was a German philosopher, physicist and experimental psychologist. An early pioneer in experimental psychology and founder of psychophysics, he inspired many 20th- century scientists and philosophers. Early Life and Scientific Career Fechner was born at Groß Särchen, near Muskau, in Lower Lusatia, where his father was a pastor. Despite being raised by his religious father, Fechner became an atheist in later life. He was educated first at Sorau. In 1817, he studied of medicine at the Medizinische Akademie Carl Gustav Carus in Dresden, and from 1818 at the University of Leipzig, the city in which he spent the rest of his life. He earned his Ph.D. from Leipzig in 1835. In 1834, he was appointed professor of physics at Leipzig. But in 1839, he contracted an eye disorder while studying the phenomena of color and vision, and, after much suffering, resigned. Subsequently, recovering, he turned to the study of the mind and its relations with the body, giving public lectures on the subjects dealt with in his books. Whilst lying in bed Fechner had an insight into the relationship between mental sensations and material sensations. This insight proved to be significant in the development of psychology as there was now a quantitative relationship between the mental and physical worlds. CU IDOL SELF LEARNING MATERIAL (SLM)

Contribution of Weber, Fechner, Wundt and Galton 41 Fig. 2.2: Gustav Theodor Fechner Influence Fechner, along with Wilhelm Wundt and Hermann von Helmholtz, is recognized as one of the founders of modern experimental psychology. His clearest contribution was the demonstration that because the mind was susceptible to measurement and mathematical treatment, psychology had the potential to become a quantified science. Theorists such as Immanuel Kant had long stated that this was impossible, and that therefore, a science of psychology was also impossible. Though he had a vast influence on psychophysics, the actual disciples of his general philosophy were few. Ernst Mach was inspired by his work on psychophysics. William James also admired his work: in 1904, he wrote an admiring introduction to the English translation of Fechner’s Büchlein vom Leben nach dem Tode (Little Book of Life After Death). Furthermore, he influenced Sigmund Freud, who refers to Fechner when introducing the concept of psychic locality in his The Interpretation of Dreams that he illustrates with the microscope-metaphor. CU IDOL SELF LEARNING MATERIAL (SLM)

42 Experimental Psychology Fechner’s world concept was highly animistic. He felt the thrill of life everywhere, in plants, earth, stars, the total universe. Man stands midway between the souls of plants and the souls of stars, who are angels. God, the soul of the universe, must be conceived as having an existence analogous to men. Natural laws are just the modes of the unfolding of God’s perfection. In his last work Fechner, aged but full of hope, contrasts this joyous “daylight view” of the world with the dead, dreary “night view” of materialism. Fechner’s work in aesthetics is also important. He conducted experiments to show that certain abstract forms and proportions are naturally pleasing to our senses, and gave some new illustrations of the working of aesthetic association. Charles Hartshorne saw him as a predecessor on his and Alfred North Whitehead’s philosophy and regretted that Fechner’s philosophical work had been neglected for so long. Fechner’s position in reference to predecessors and contemporaries is not very sharply defined. He was remotely a disciple of Schelling, learnt much from Baruch Spinoza, G.W. Leibniz, Johann Friedrich Herbart, Arthur Schopenhauer, and Christian Hermann Weisse, and decidedly rejected G.W.F. Hegel and the monadism of Rudolf Hermann Lotze. Fechner’s work continues to have an influence on modern science, inspiring continued exploration of human perceptual abilities by researchers such as Jan Koenderink, Farley Norman, David Heeger, and others. Honours Fechner Crater In 1970, the International Astronomical Union named a crater on the far side of the moon after Fechner. Fechner Day In 1985, the International Society for Psychophysics called its annual conference Fechner Day. The conference is now scheduled to include 22 October to allow psychophysicists to celebrate the anniversary of Fechner’s waking up on that day in 1850 with a new approach into how to study the mind. Fechner Day runs annually with the 2018 Fechner Day being the 34th. It is organized annually, by a different academic host each year. CU IDOL SELF LEARNING MATERIAL (SLM)

Contribution of Weber, Fechner, Wundt and Galton 43 Family and Later Life Little is known of Fechner’s later years, nor of the circumstances, cause, and manner of his death. Fechner was the brother of painter Eduard Clemens Fechner and of Clementine Wieck Fechner, who was the stepmother of Clara Wieck when Clementine became her father Friedrich Wieck’s second wife. 2.5 Contribution of Fechner German experimental psychologist who founded psychophysics and formulated Fechner’s law, a landmark in the emergence of psychology as an experimental science. Gustav Theodor Fechner was born on 19 April 1801, at Gross-Särchen, Lower Lusatia. He earned his degree in biological science in 1822 at the University of Leipzig and taught there until his death on 18 November 1887. Having developed an interest in mathematics and physics, he was appointed professor of physics in 1834. About 1839, Fechner had a breakdown, having injured his eyes while experimenting on afterimages by gazing at the sun. His response was to isolate himself from the world for three years. During this period, there was an increase in his interest in philosophy. Fechner believed that everything is endowed with a soul; nothing is without a material basis; mind and matter are the same essence, but seen from different sides. Moreover, he believed that, by means of psychophysical experiments in psychology, the foregoing assertions were demonstrated and proved. He authored many books and monographs on such diverse subjects as medicine, esthetics, and experimental psychology, affixing the pseudonym Dr. Mises to some of them. The ultimate philosophic problem which concerned Fechner, and to which his psychophysics was a solution, was the perennial mind-body problem. His solution has been called the identity hypothesis: mind and body are not regarded as a real dualism, but are different sides of one reality. They are separated in the form of sensation and stimulus; that is, what appears from a subjective viewpoint as the mind, appears from an external or objective viewpoint as the body. In the expression of the equation of Fechner’s law (sensation intensity = C log stimulus intensity), it becomes evident CU IDOL SELF LEARNING MATERIAL (SLM)

44 Experimental Psychology that the dualism is not real. While this law has been criticized as illogical, and for not having universal applicability, it has been useful in research on hearing and vision. Fechner’s most significant contribution was made in his Elemente der Psychophysik (1860), a text of the “exact science of the functional relations, or relations of dependency, between body and mind,” and in his Revision der Hauptpunkte der Psychophysik (1882). Upon these works mainly rests Fechner’s fame as a psychologist, for in them he conceived, developed, and established new methods of mental measurement, and hence the beginning of quantitative experimental psychology. The three methods of measurement were the method of just noticeable differences, the method of constant stimuli, and the method of average error. According to the authorities, the method of constant stimuli, called also the method of right and wrong cases, has become the most important of the three methods. It was further developed by G.E. Müller and F.M. Urban. William James, who did not care for quantitative analysis or the statistical approach in psychology, dismisses the psychophysic law as an “idol of the den,” the psychological outcome of which is nothing. However, the verdict of other appraisers is kinder, for they honor Fechner as the founder of experimental psychology. Psychophysics The problem that concerned Fechner most was the connection between body and mind. His Elemente der Psychophysik (1860) aims at utilizing experimental procedures, such as those employed by Weber previously, to explore this connection more precisely, arriving, if possible, at mathematically formulated laws. Earlier, Johann Friedrich Herbart had demanded that psychological laws be formulated in mathematical terms, but he despaired of the likelihood that psychology would ever obtain the necessary experimental data. Fechner saw in Weber’s threshold experiments the possibility of securing such data. He assumed that the difference between two sensations may be defined by the number of “just noticeable differences” (jnd) between them, and that these jnds can be represented mathematically. He used the number of jnds above the lower absolute threshold as a measure of the intensity of sensation evoked by a stimulus. In order to be able to describe the relationship between psychic and physical CU IDOL SELF LEARNING MATERIAL (SLM)