PSYC1002 Lecture Notes - Lecture 3: Mental Chronometry, Franciscus Donders, Behaviorism
19 May 2018
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Department
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Professor
Reading: Chapter 5 Snodgrass
Measuring speed of mental events (mental chronometry)
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Not popular until revived 60 years later
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Reformed via Saul Sternberg's additive factors method
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Influenced by Helmholtz, attempted to measure speed of nerve transmission in frog by
measuring time between stimulation of part of frog and resulting muscular contraction
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Applied same to humans via mild electric shock
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Method of subtraction = measured diff in time between stimulation of elbow and
stimulation of hand
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Used approx length of nerve fibres between hand and elbow and difference in reaction
time as measure of nerve transmission time
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Simple reaction time - time between when single stimulus creates single simple
response
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No less than 12 mental events must occur between presentation of stimulus and motor
response in simple reaction time
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Includes time to discriminate between stimuli (discrimination time) and time to
select one of the several motor responses (motor choice time)
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Choice reaction time - 2 or more stimuli, and subject indicates which stimulus presented
by producing one of 2 or more responses, diff response for each stimulus
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Difference between simple reaction time and choice reaction time = sum of
discrimination time and motor choice time
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Donders subtraction method
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Believe 3 processes
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Stimulus input time
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Central processing/decision time
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Motor response time
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Present day theorists
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History of cognitive psyc
1914
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Rejected internal mental structures
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Only learn something if rewarded
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Watson - behaviourist view of psyc is a purely objective, experimental branch of natural
science, behaviour of animals can be investigated without appeal to consciousness
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Skinner
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Behaviourism (Watson and Skinner)
Rats in maze, finding food
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Has rat learned about maze or how to get to the food
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Control - run in maze once a day and found food
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Experimental - not fed at all while in maze for 7 days, then rewarded in maze from then
3 groups
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Tolman and cognitive maps
L1
Tuesday, 1 August 2017
7:49 AM
Cognitive Page 1
Experimental - not fed at all while in maze for 7 days, then rewarded in maze from then
on
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Experimental - not fed at all while in maze for 3 days, then rewarded in maze from then
on
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To understand limits
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Discovering human limitations in mental processing
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Need for better training and design
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Attentional overload
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Allow us to investigate mental processes scientifically
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Use computers as "model" for human information-processing systems
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Construct model of cognitive processes and test model by measuring human behaviour
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Computers take in and manipulate info
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Encoding -> Storage -> retrieval = entering data through keyboard -> saving data on
computer -> calling up file and displaying data on screen
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Role of technology
Methods of measuring speed and organisation of mental processes
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Compare behaviour in 2 tasks that differ in only one mental process
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Simple = press any button to any light
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Choice = press on button to red light, another for green light
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Choice RT - Simple RT = estimate of stimulus evaluation time
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e.g. simple vs choice reaction time
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Infer nature of processes
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People may search for items in parallel (at same time) or serially (one by one)
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People may stop searching once item is found (self-terminating) or keep searching
through whole set regardless (exhaustive)
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Can infer how people search through their memory e.g. Sternberg memory scanning
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Mental chronometry (snodgrass)
Cognitive processes investigated indirectly
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Introspective data do not provide valid insight into determinants of cognition
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Some cognitive processes occur without any conscious awareness or control and therefore
can't be investigated
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Consciously controlled processes subject to cognitive biases and reasoning errors which
influence interpretation of events without our awareness
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Influenced by FRAMING (e.g. wording of the problem e.g. buy one get one free)
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Hindsight bias - "I knew it all along"
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Confirmation bias - seek info that confirms beliefs and ignore info that doesn't
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Seek order in randomness and ignore chance
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Ignore sample size
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Errors can make us more efficient at processing info, but doesn't mean we can't accurately
report on our own cognitive processes
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Framing effects and cognitive bias
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Memory involves more than taking information in and storing it in some mental compartment
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How does info get into memory
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How is info maintained in memory
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How is info pulled back out of memory
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3 main questions of memory
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Ch 7 Weiten Psyc p273-6
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Involves forming a memory code
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e.g. emphasise how it looks/sounds/means
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Requires attention usually
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Forgetting often from failure to form a memory code
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Need to pay attention to information if you intend to remember it
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Attention = focusing awareness on a narrow range of stimuli or events
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Selective attention important, screen out most of the potential stimulation
around you
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Similar to filter that screens out potential stimuli, so only few pass through
into the conscious awareness
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Unsure WHERE the filter is located
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Cocktail party phenomenon - suggests stimuli screened out late, after brain
has processed the meaning/significance of the input
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Early selection vs. late selection evidence
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Perhaps location of attention filter may be flexible not fixed
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Attention diverted
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Encoding - getting info in
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3 key processes
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L2 - attention
Tuesday, 1 August 2017
7:59 AM
Cognitive Page 3
Document Summary
Influenced by helmholtz, attempted to measure speed of nerve transmission in frog by measuring time between stimulation of part of frog and resulting muscular contraction. Applied same to humans via mild electric shock. Method of subtraction = measured diff in time between stimulation of elbow and stimulation of hand. Used approx length of nerve fibres between hand and elbow and difference in reaction time as measure of nerve transmission time. Simple reaction time - time between when single stimulus creates single simple response. No less than 12 mental events must occur between presentation of stimulus and motor response in simple reaction time. Choice reaction time - 2 or more stimuli, and subject indicates which stimulus presented by producing one of 2 or more responses, diff response for each stimulus. Includes time to discriminate between stimuli (discrimination time) and time to select one of the several motor responses (motor choice time)
