Chapter 1 from Cognition (4th edition).docx

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18 Apr 2012
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Chapter 1 - Intro
-scientific psychology looks to redefine folk psychology (a set of assumptions and theories based on
everyday behaviours of ourselves and others)
-definitions:
Oxford Dictionary:
Action or faculty of knowing - it is the action of knowing (the study of processes, the
ways in which we become acquainted with things) - it is a faculty (the mind can be
divided into faculties that represent different mental activities)
Awareness (consciousness)
Comprehension (quickness of learning, info, sagacity)
Intuition (immediate insight)
Personal acquaintance (social knowledge)
Recognition (categorizing, reviewing and revising)
Skill (reasoning, practice knowledge, experience)
Understanding (judgement, decision-making, comprehension)
-G.A. Miller (1986) - one of the founders of cognitive psychology
-cognitive psychology and information-processing theory :
Info-processing is the subject matter of cog psy
Idea came from communication engineering - all communication can be broken down
into 3 major stages:
Sender - encodes message
Communication channel - transmits signals
Receiver - decodes (translates) signals to get message
Info-processing theory:
Information reduces uncertainty in the mind of the receiver
The amount of information provided by a message is proportional to the probability of
that message occurring
The information provided by a particular message is not determined solely by
the signal itself but rather by the whole array of possible messages of which this
particular signal is just one
Underlying idea of theory
Info provided is inversely related to its probability of occurring - the less likely a signal is,
the more info it conveys
Amount of info provided by occurrence of event is quantified by "bits" - 'binary
digit'
Early tests:
Merkel in 1885 - demonstrated people respond more slowly to less likely signals
- results show that as number of alternatives increased from 1 to 10, so did the
response time
Hicks in 1952 - confirmed Merkel's results - light stimuli and depression keys for
response - stimulus information is intimately concerned with response time
When the set of stimuli is small, there is little uncertainty as to which
signal will occur, so the information produced by stimulus is small
When group of possible signals grows in size, uncertainty increases as to
which signal will occur and so the amount of info produced by a stimulus
increases
Crossman and Hyman in 1953 - confirmed previous statements and added that
response time to frequent signals was reduced - also introduced sequential
dependencies : response time became faster as signal's probability increased
People take longer to react to an improbable stimulus (conveys more
information) than a probable stimulus (conveys less info)
Response time is proportional to signal info, regardless of how the info is varied
Info-processing limitations
The amount of time it takes for info to flow though the nervous system is a
limitation on info-processing capacity
Nervous system can only handle a limited amount of info within a fixed period
of time
Webster and Thompson (1953) experiment - control tower operators could
identify call signals from two airplanes arriving simultaneously (since they had
an idea as to what it could be) but could only identify one of two simultaneous
word messages
This suggests that nervous system is of limited capacity in info-processing
sense
Words come from large ensemble of possible signals - difficult to do
another task at the same time
Airplane calls come from small and familiar set of possible signals -
possible to do something else at the same time
Difficulty in dealing with 2 signals coming in at once arises because
people are limited in amount of info that they can deal with at one
time
2 tasks can be done at once if they both have low info value
Broadbent (1956) - the limit "is one of information rather than
stimulation"
Over-loading of capacity is dealt with by the person's selecting only some of the
total available information; particularly info that shares some basic physical
property (arriving in a particular voice or from a certain location in space)
Humans actively select information from environment - only some of it is
processed, responded to, and remembered
Cherry's (1953) experiment shows that variation can occur in efficacy with which
limited capacity resources can be directed to most relevant information
Models of info-processing
There are several models of relations b/w different cog processes
Two classic models:
Broadbent's Filter Model:
What control do people have over which information is selected
and which is rejected ?
Theory is based on idea that info -processing is restricted by channel
capacity (maximum amount of info that can be transmitted by info-
processing device)
Whole nervous system is a single channel - has limit to rate of
stimulus info transmission - this limited capacity channel is
preceded by selective filter which might pass along only some of the
available incoming info in order to avoid overloading the channel -
preceding the filter is a capacity-free sensory buffer (temporary
store)
Buffer extracts simple stimulus characteristics (colour, voice,
spatial location)
Filter selects messages that share common basic physical
characteristics
Limited capacity system responsible for analysis of 'higher
order' stimulus attributes (form, meaning)
Other messages held in parallel in sensory buffer where they
will decay over time
At the time, presented strong account of the data on attention at
the time
Experiment with navy soldiers listening to pairs of numbers was
interpreted by Broadbent to mean that ears function as separate
channels for info input - switching attention between ears requires
time - while attention is being switched info is decaying in sensory
buffer, becoming less available
Waugh and Norman's Model of Info-Processing
Upon being stimulated, we may experience primary memory (a
concept derived from William James, perhaps the most influential of
all American psychologists)
James got many of his major insights and hypotheses by
introspection (act of observing one's own thoughts and
feelings)
Primary memory consists of the immediately present moment -
'immediate memory' - belongs to the present
Rehearsal conveys that primary memories tend to be quickly
forgotten unless they are repeated
Secondary memory - knowledge of former state of mind after it has
been absent from awareness for some time - 'long-term memory' -
belongs to the past
Experimental evidence for primary/secondary memory distinction
came from analysis of Brown-Peterson task
Experimental paradigm where subjects are given a set of
items and then a number, they immediately begin counting
backward by threes from the number, after a specific interval
subjects are asked to recall the original items