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Donders Method of Subtraction & Helmholtzs Idea of Unconscious Inference Psychology 355: Cognitive Psychology Instructor: John Miyamoto 04/02 /2014: Lecture.

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Presentation on theme: "Donders Method of Subtraction & Helmholtzs Idea of Unconscious Inference Psychology 355: Cognitive Psychology Instructor: John Miyamoto 04/02 /2014: Lecture."— Presentation transcript:

1 Donders Method of Subtraction & Helmholtzs Idea of Unconscious Inference Psychology 355: Cognitive Psychology Instructor: John Miyamoto 04/02 /2014: Lecture 01-3 This Powerpoint presentation may contain macros that were used to create the slides. The macros arent needed to view the slides. If necessary, you can disable the macros without any change to the presentation.

2 Outline Donders Method of Subtraction Method of Subtraction in fMRI Unconscious Inference The dominance of behaviorism, 1920 – 1960 (approx.) The resurgence of cognitive psychology, 1950 – 1970 (approx.) Psych 355, Miyamoto, Spr '14 2

3 3 Overview of the History of Cognitive Psychology Precursors to cognitive psychology Aristotle, Plato – epistemology, theory of ideas and their relation to human action Experimental psychology begins in 19th century Germany Franciscus Donders (response time analysis, method of subtraction) Hermann von Helmholtz (perception, unconscious inference) Hermann Ebbinghaus (experimental study of memory) Wilhelm Wundt (analytic introspection, analysis of conscious experience) Behaviorist hiatus in America: roughly 1920 – 1960 During the behaviorist period ( ), cognitive psychology continued to be studied in Europe. Revival of cognitive psychology in America (1950 – 1970) 1970 – present: Cognitive psychology plays a major role in psychology pretty much everywhere in the world Donders Mental Chronometry

4 Psych 355, Miyamoto, Spr '14 4 Early Cognitive Psychology: F.C. Donders ( ) Mental chronometry: Measuring how long a cognitive process takes Reaction-time (RT) Experiment (a.k.a. response time experiment): Measures interval between stimulus presentation and the response to the stimulus Method of Subtraction: Used to infer how long a mental process takes when the process is not directly observable. Method of subtraction is an example of a behavioral research method. Definition of Response Time (RT)

5 Terminology: RT (Response Time, Reaction Time) RT = response time (a.k.a. reaction time) RT = (Response Completion) – (Stimulus Onset) Obviously to measure RT, the experimenter has to be able to measure precisely when the stimulus was presented, and when the subject completed the response. Psych 355, Miyamoto, Spr '14 5 Definition of Simple RT and Choice RT

6 Psych 355, Miyamoto, Spr '14 6 Method of Subtraction Applied to the Comparison Between Simple and Choice Reaction Time Simple RT task: Participant pushes a button quickly after a light appears Choice RT task: Participant pushes one button if light is on the right side, and a different button if light is on left side Donders goal: To measure how long it takes a person to decide which button to press in the choice RT task. How long is the decision process? Diagram Showing Time Course of Simple RT

7 Diagram of Cognitive Processes During Simple RT Simple RT = (Response Completion) – (Stimulus Onset) In a simple RT task, the subject does not have to decide how to respond. Psych 355, Miyamoto, Spr '14 7 Time Diagram Showing Time Course of Choice RT

8 Diagram of Cognitive Processes During Choice RT Choice RT = (Response Completion) – (Stimulus Onset) In a choice RT task, the subject has to decide which response is appropriate. Psych 355, Miyamoto, Spr '14 8 Time Diagram showing the Decision Stage in the Information Process

9 Psych 355, Miyamoto, Spr '14 9 Decision time = the length of time that it takes to decide which response is appropriate. Diagram of Cognitive Processes During Choice RT Question for the Class: How to Measure Decision Time? Decision Time

10 Question for the Class: How Can We Measure the Duration of the Decision Stage in a Choice RT Task? Donders goal: To measure how long it takes a person to decide which button to press in the choice RT task. How long is the decision process? Psych 355, Miyamoto, Spr '14 10 Diagram comparing simple and choice RT

11 Method of Subtraction: Compare Simple RT to Choice RT Method of Subtraction: Choice RT – Simple RT = Duration of Decision Stage (red) Psych 355, Miyamoto, Spr '14 11 Simple RT Choice RT Diagram Showing that the Perceiving Stages are Identical

12 Method of Subtraction: Compare Simple RT to Choice RT Psych 355, Miyamoto, Spr '14 12 Simple RT Choice RT Diagram Showing that the Responding Stages are Identical Same Duration

13 Method of Subtraction: Compare Simple RT to Choice RT Psych 355, Miyamoto, Spr '14 13 Simple RT Choice RT Diagram Showing that the RT Difference Measures the Duration of the Decision Stage Same Duration

14 Psych 355, Miyamoto, Spr '14 14 Method of Subtraction: Choice RT – Simple RT = Duration of Decision Stage (red) Method of Subtraction: Compare Simple RT to Choice RT Simple RT Choice RT What does Donders Method Show About Cognitive Psych? Same Duration

15 Why is Donders Method of Subtraction Important for Cognitive Psychology? It combines a behavioral study with a simple computational model of a cognitive process. In Psych 355, we will see many behavioral studies of cognition. In Psych 355, we will not study the mathematical details of computational models of cognition. Purely or strictly behavioral studies – no physiological measurements; no brain imaging. Psych 355, Miyamoto, Spr '14 15 fMRI Method of Subtraction

16 Subtraction Methods in fMRI Brain Imaging Activations are regions of significant change from a control condition to a test condition. Psych 355, Miyamoto, Spr '14 16 Brain image shows regions of significant activation when comparing Test Condition to Control Condition. (Slice of brain is viewed from above.) The purpose of this slide is simply to show that subtraction methods are used in modern fMRI studies. Specific details are not important. Example: Test Condition: Subject views picture. Control Condition: Subject fixates a blank screen. Helmholtz & Unconscious Inference

17 Early Cognitive Psychology: H. L. F. von Helmholtz (1821 – 1894) Great mathematician, physicist, psychologist Contributions to psychology: perception, especially color vision, hearing, optics, unconscious inference Unconscious inference Some of our perceptions are the result of unconscious assumptions we make about the environment We infer much of what we know about the world Psych 355, Miyamoto, Spr '14 17 Diagram that Illustrates Unconscious Inference (Occlusion)

18 Psych 355, Miyamoto, Spr '14 18 Unconscious Perceptual Inference The display in (a) looks like (b) a gray rectangle in front of a light rectangle; but it could be.... … (c) a gray rectangle and a six-sided figure that are lined up appropriately or (d) a gray rectangle and a strange-looking figure that are lined up appropriately. Repeat this Slide without the Rectangles

19 Psych 355, Miyamoto, Spr '14 19 Unconscious Perceptual Inference The display in (a) looks like (b) a gray rectangle in front of a light rectangle; but it could be.... … (c) a gray rectangle and a six-sided figure that are lined up appropriately or (d) a gray rectangle and a strange-looking figure that are lined up appropriately. Why is Unconscious Inference Important?

20 Psych 355, Miyamoto, Spr '14 20 Why Is the Idea of Unconscious Inference Important? Unconscious inferences contribute in many ways to the formation of our perceptions and beliefs. Cognitive psychology attempts to reveal the processes by which such inferences are made. Other Early Cognitive Psychologists – Ebbinghaus & Wundt

21 Psych 355, Miyamoto, Spr '14 21 Other Important Early Cognitive Research Ebbinghaus (1850 – 1909) and the Method of Savings Important memory research We will talk about this later in the course Wundt (1832 – 1920) How sensations combine to form percepts Analytic introspection Behaviorist Hiatus

22 Psych 355, Miyamoto, Spr '14 22 Behaviorist Hiatus – Roughly John Watson Influenced by positivist philosophy. The goal of science is to predict whatever is observable. Science should eliminate assumptions about whatever is not observable. (Questionable) Consciousness is not observable. Eliminate it from psychological theory. Anti-introspectionist. Opposed to theories that postulated unobserved psychological processes Clark Hull – Stimulus/Response (S/R) learning model. Edwin Guthrie B. F. Skinner – Reinforcement theory Behaviorism was an American approach to psychology – not so influential in Europe and elsewhere. Cognitive Psychology During the Behaviorist Period

23 William James (1842 – 1910; cognitive psychology) Jean Piaget – genetic epistemology Lev Vygotsky – cognitive development and education Sir Frederick Bartlett (constructive memory processes) Gestalt psychology – Kurt Lewin, Wolfgang Kohler The beginnings of the computer revolution. Alan Turing, Norbert Wiener, John von Neumann Psych 355, Miyamoto, Spr '14 23 Behaviorism Loses Its Grip on Psychology

24 Psych 355, Miyamoto, Spr '14 24 Wednesday, April 02, 2014 : The Lecture Ended Here


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