Historical Foundations of Cognitive Psychology Cognitive Psychology
¥ Tim Curran ¥ A Definition ¥ [email protected] Ð The scientific study of mental processes such as perceiving, remembering, using language, ¥ Lecture slides are available at: reasoning, and solving problems. http://psych.colorado.edu/~tcurran/oreilly.html ¥ The formal discipline of “Cognitive * BUT YOU SHOULD STILL TAKE NOTES! Psychology” started in the mid-1900’s. ¥ Read Chapter 1 in Text ¥ It’s roots can be traced back much further.
Later Philosophy Greek Philosophers (1600s - 1800’s) (4th-5th Century BC) ¥ Nativism (since Plato) Ð Knowledge is innate Ð Influential figures: Plato & Aristotle ¥ heredity, nature Ð Began to consider questions about perception, memory, ¥ Empiricism and thought. Ð Influential figures: Hobbes & Locke ¥ Plato = Rationalist Ð Knowledge is gained through experience Ð Emphasized logical analysis. ¥ Aristotle = Empiricist ¥ learning, nurture Ð Emphasized observations of the external world. Ð Associationism Ð Specific assumptions, allowing for tractable questions: ¥ Knowledge originates from interconnected information. ¥ The world can be understood and predicted. Ð BANNANA-YELLOW-FRUIT-PEEL-LONG ¥ Humans are part of that world. ¥ Key principle of modern “neural network” models. ¥ Explanations should be of this world. ¥ Compromise Positions Ð Influential figures: Descartes & Kant Ð Both Nurture and Nature are important. Influence of Philosophy on German Physicists Cognitive Psychology (1800s) • Influential figures: ¥ Contribution to Cognitive Psychology • Helmholtz: Color vision Ð Identified many fundamental questions and • Fechner: Psychophysics assumptions about the nature of the mind. • Relationship between physical changes in stimuli and sensory experience. ¥ Limitations • Applied scientific methods. Ð Lacked scientific methods. • Contribution to Cognitive Psychology • Use of scientific/experimental methods. • Limitation • Limited to the study of simple sensory processes.
Early Scientific Psychology Structuralism ¥ Influential figure: Wilhelm Wundt ¥ Structuralism • Focus on identifying the basic building blocks of conscious experience. ¥ Functionalism • Analogy with periodic table of elements in chemistry. ¥ Behaviorism • Main method: "Introspection" under controlled conditions. ¥ Contribution to Cognitive Psychology Ð Emphasized systematic, controlled observation. Ð Importance of the understanding the structure of the mind, and higher cognitive processes. ¥ Limitation Ð Reliance on introspection. Behaviorism Functionalism ¥ Influential figures: John B. Watson, B. F. Skinner ¥ Influential figure: William James ¥ Guiding Principles: Ð Only focus on that which is observable. ¥ Mental processes must be adaptive, so what are Ð Explain behavior; not thought, consciousness, etc. they good for? Ð Theories should be simple. Ð e.g., practical uses and functions Ð Break down behavior into irreducible constructs. • Main method: Rigorous experimentation Ð Inspired by evolutionary theory. • ¥ Main methods: Contribution to Cognitive Psychology Ð Introspection, questionnaires, mental tests, animal Ð Emphasis on rigorous experimentation. experiments Ð Powerful theories of learning ¥ Contribution to Cognitive Psychology ¥ Classical Conditioning Ð Learning relationships among stimuli. Ð Emphasis on the functions and applications. Ð e.g., Pavlov’s dog learned relationship between bell and food. ¥ Limitation ¥ Operant Conditioning Ð Methods not very rigorous. Ð Learning responses that are rewarded. Ð e.g., A dog learns to sit for a treat.
¥ Failure to consider intervening mental processes Limitations of Behaviorism Ð Behaviorism: Stimuli Responses ¥ Failures to account for aspects of human behavior Ð Cognitive Psychology Ð Over-emphasis on animal experimentation Ð Language Stimuli Mental Processes Responses ¥ Skinner suggested language was learned through basic principles of operant conditioning. Ð Stimulus (memorize this list) Ð i.e., we learn to say what is rewarded ¥ lion, onion, Bill, firefighter, carrot, ¥ Fails to account for Generativity of language. zebra, John, clerk, Tim, nurse, cow Ð The creation of novel utterances that have never been rewarded in the past. Ð Response (recall) Ð e.g., Chomsky (linguist) ¥ lion, zebra, cow, onion, carrot, firefighter, clerk , nurse, John, Bill, Tim Ð Mental Processes ¥ Strategies, grouping, reorganization, etc. Overview of Different Approaches Stimuli Mental Processes Responses Outside Influences in mid 1990’s ¥Philosophy ¥Argue about mental processes ¥ Interest in optimizing human performance ¥Introspection Ð World War II ¥Directly tap into mental processes ¥ Computer Science ¥Behaviorism Ð Artificial Intelligence ¥Study stimulus-response relationships Ð Computer Metaphor ¥Ignore mental processes ¥ Information processing, memory buffers, etc. ¥Cognitive Psychology ¥Study stimulus-response relationships ¥Make inferences about mental processes
Information Processing Analysis Example Information Processing ¥ The dominant approach toward studying human cognition. ¥ Decomposing a cognitive task into a set of abstract information processing steps. ¥ Designing experiments to understand the characteristics of each stage. Representations & Processes Sternberg’s Memory Scanning Task
¥ A representation is a symbol for an entity in the real world. Ð e.g., computers represent numbers in a binary code ¥ “8” = “0-1-1” ¥ A process manipulates/transforms representations in some way. Ð e.g., addition, multiplication, etc http://coglab.psych.purdue.edu/coglab/
Information Processing Stages Possible Search Processes in the Memory Scanning Task 1. Serial, Exhaustive Search Ð Whole letter set is always searched, one by one. Search ¥ RT increases with set size, and Yes = No Encode Decide Respond Memory
L AKLM L Yes = / ? No = z AKLM
(stages during probe recognition phase) Possible Search Processes Possible Search Processes 2. Serial, Self-terminating Search 3. Parallel Search Ð Letters searched one by one until target is found or Ð All letters in set simultaneously identified. search is complete. ¥ RT increases with set size, but faster for “yes” responses ¥ RT unaffected by set size or yes/no. because search stops when the target is found in the set.
Encode Search Decide Respond Summary of Information Sternberg’s Results Processing Approach ¥ Decomposing a cognitive task into a set of abstract information processing stages. ¥ Serial Exhaustive Search ¥ Attempts to understand Ð Search rate inferred from slope = 38 ms per item processes/representations within each stage. ¥ Encoding/Decision/Response ¥ A given stage (e.g., memory search) can be Stages Ð Combined speed is y-intercept studied by manipulating variables (e.g., set = 397 ms size) hypothesized to affect that stage, and Ð Don’t vary with set size observing performance (e.g., reaction time). Ð Vary with variables that should affect these processes.