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Chapter 1 Introduction to Cognitive Psychology

Chapter 1 Introduction to Cognitive Psychology. The Complexity of Cognition. Cognition involves Perception Attention Memory Problem solving Reasoning Decision making All include “hidden” processes of which we may not be aware. The First Cognitive Psychologists. Donders (1868)

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Chapter 1 Introduction to Cognitive Psychology

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  1. Chapter 1Introduction to Cognitive Psychology

  2. The Complexity of Cognition • Cognition involves • Perception • Attention • Memory • Problem solving • Reasoning • Decision making • All include “hidden” processes of which we may not be aware

  3. The First Cognitive Psychologists • Donders (1868) • Mental chronometry • Measuring how long a cognitive process takes • Reaction-time (RT) Experiment • Measures interval between stimulus presentation and person’s response to stimulus

  4. The First Cognitive Psychologists • Donders (1868) • Simple RT task: participant pushes a button quickly after a light appears • Choice RT task: participant pushes one button if light is on right side, another if light is on left side

  5. Simple RT Choice RT

  6. The First Cognitive Psychologists • Donders (1868) • Choice RT – Simple RT = Time to make a decision • Choice RT = 2.1 sec • Simple RT = 2 sec • 1/10th sec to make decision

  7. The First Cognitive Psychologists • Donders (1868) • Mental responses cannot be measured directly but can be inferred from the participant’s behavior.

  8. The First Cognitive Psychologists • Helmholtz (~1860s) • 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

  9. Caption: 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.

  10. The First Cognitive Psychologists • Ebbinghaus (1885) • Read list of nonsense syllables aloud many times to determine number of repetitions necessary to repeat list without errors

  11. The First Cognitive Psychologists • Ebbinghaus (1885) • After some time, he relearned the list • Short intervals = fewer repetitions to relearn • Learned many different lists at many different retention intervals

  12. The First Cognitive Psychologists • Ebbinghaus (1885) • Savings = [(initial repetitions) – (relearning repetitions)] /(initial repetitions) • S = (Ri-Rr)/Ri • Forgetting curve shows savings as a function of retention interval

  13. Ebbinghaus’s retention curve, determined by the method of savings. (Based on data from Ebbinghaus, 1885.)

  14. The First Cognitive Psychologists • Wundt (1897) • First psychology laboratory • University of Leipzig, Germany • RT experiments

  15. The First Cognitive Psychologists • Wundt (1897) • Structuralism: experience is determined by combining elements of experience called sensations gustatory olfactory visual auditory haptic

  16. The First Cognitive Psychologists • Wundt (1897) • Analytic introspection: participants trained to describe experiences and thought processes in response to stimuli

  17. The First Cognitive Psychologists • John Watson noted two problems with this: • Extremely variable results from person to person • Results difficult to verify • Invisible inner mental processes

  18. The Rise of Behaviorism • John Watson proposed a new approach called behaviorism • Eliminate the mind as a topic of study • Instead, study directly observable behavior

  19. The Rise of Behaviorism • Watson (1920) – “Little Albert” experiment • 9 month old became frightened by a rat by pairing a loud noise with every presentation of the rat

  20. The Rise of Behaviorism • Watson (1920) – “Little Albert” experiment • Behavior can be analyzed without any reference to the mind • Examined how pairing one stimulus with another affected behavior In summary: cognitivism was in crisis…

  21. 9am

  22. Skinner: S R Operant conditioning: reinforcers [e.g. food] “Verbal behavior” (1957): language learned via imitation and reward. Chomsky: kids use untrained sentences; make errors given reward. COGNITIVE REVOLUTION MIND = COMPUTER -information-processing device -several stages

  23. computer I Input processor Memory unit Arithmetic unit O human I Filter Detector To memory Cherry (1953) experiment physiological R Attend Left mental R attended sentences remembered behavioral R

  24. RT Angle difference Brain activity remembered forgotten RESULT OF MEMORY TEST Mental rotation: Shepard & Metzler (1971) Same or different? Davachi et al (2003): Measure brain activity during learning read 200 words: create an image “dirty” = “garbage dump” 20 hrs later: same 200 words “did you see this word?” Y/N Result: 54% from the 1st group remembered

  25. 10am

  26. sound to electricity Motor area • + Knowledge: • Alarm will go off again in 10 min • Still time to get to class Auditory area to arm and hand

  27. receptor dendrites S axon spikes = action potentials axon voltage minielectrode 1/10 sec 1/1000 sec oscilloscope Neurons: building blocks of nervous system Golgi first to prove how a neuron looks like TRANSDUCTION: energy to energy conversion (just like ATM) Why study single neurons?

  28. SIGNAL PROPAGATION without decrease in size axon Stimulus intensity represented by firing rate, not spike magnitude

  29. Direct contact? (touch?) NO! SYNAPSE (space between axon and next neuron) E increased firing electrodes decreased firing I HOW NEURONS COMMUNICATE? Early 1900s: action potentials DO NOT travel across synapses -they TRIGGER a chemical process -synaptic VESICLES open and release chemicals (NEUROTRANSMITTERS)

  30. Firing rate (B) 1 2 3 4 5 6 7 EXCITATORY NEURAL CIRCUIT A C B Properties: CONVERGENCE INTERACTION OF E & I 4 3-5 2-6 1-7 Receptors

  31. Firing rate (B) 1 2 3 4 5 6 7 INHIBITORY NEURAL CIRCUIT A C B 4 3-5 2-6 1-7 Receptors

  32. time time time time Optic nerve brain areas: neurons ever more specialized Hubel & Wiesel (1965): feature detectors End-stopped cells simple cells complex cells

  33. …but how to recognize a specific face? NEURAL CODES convergence + excitation + inhibition

  34. firing rate neurons firing rate neurons SPECIFICITY CODING: representation of a specific stimulus GRANDMOTHER CELL: responds to only one stimulus DISTRIBUTED CODING: the pattern matters, not cells

  35. 11am

  36. BRAIN LOBES: outer covering = cerebral cortex Vision Attention Touch Motor function Language Thought Memory FRONTAL PARIETAL Vision OCCIPITAL TEMPORAL Language Memory Hearing Form perception

  37. THALAMUS Vision Hearing Touch HIPPOCAMPUS Memory AMYGDALA Emotions Emotional memory CEREBELLUM Sensory integration Motor control SUBCORTICAL AREAS (INSIDE THE BRAIN)

  38. NEUROPSYCHOLOGY: behavior after brain damage Behavioral breakdowns specific to brain damage. SINGLE DISSOCIATION: STM intact, LTM lost DOUBLE DISSOCIATION: Person 1: STM intact, LTM lost Person 2: STM lost, LTM intact • Proof that • STM & LTM have different mechanisms • STM & LTM independent of one another

  39. _ = stimulation difference control COGNITION: how to measure it in the brain? BRAIN IMAGING PET (positron emission tomography): -blood flow indicates cognitive process -radioactive stuff injected into blood -machine measures radioactivity levels SUBTRACTION TECHNIQUE:

  40. Active area less oxygen, more iron fMRI: functional magnetic resonance imaging -no radioactive material involved -hemoglobin carries oxygen -contains iron molecules -have magnetic properties

  41. “greebles” BRAIN IS ADAPTIVE, FLEXIBLE teaching neurons new tricks EXPERIENCE-DEPENDENT PLASTICITY firing rate before training after training

  42. 1pm

  43. “perception is simple and easy” 1960s: “will build robot within 10 years that can see, feel and act like human” Stimulus energy & [knowledge, context, experience]

  44. briefly flash stimulus K K K K Related 83% correct Misleading 40% correct Unrelated 50% correct Palmer (1975): Context influences perception Follow the lead of early cognitive psychologists… TASK: perceive letters THEORY: TEMPLATE MATCHING (perception based on features) need template for every orientation How would a machine do it?

  45. Word FORK ROOF Letter F K O R Feature Stimulus K INTERACTIVE ACTIVATION MODEL (McClelland & Rumelhart, 1981) strongest activation wins

  46. WORD RECOGNITION Word FORK ROOF Letter-position F F F F K K K K O O O O R R R R Feature Stimulus FORK F,R,K K R, K O O, R F strongest activation wins

  47. WORD SUPERIORITY EFFECT (Reicher, 1969) stimulus mask present Which appeared? flashed K a) FORK XXXX XXXX QUICK & ACCURATE M K b) K XXXX XXXX SLOW & INACCURATE M K c) RFOK XXXX XXXX SLOW & INACCURATE M -LETTERS IN WORDS AFFECTED BY CONTEXT -LETTERS IN WORDS NOT PROCESSED LETTER BY LETTER

  48. FORK ROOF F1 K4 O2 R3 WORDS LETTERS FEATURES FEEDBACK ACTIVATION explains this result: -no feedback when standalone letter presented -word level sends FB to letter level as reinforcement TOP-DOWN FB BOTTOM-UP PROCESSING

  49. 2pm

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