Information Processing
• Assumptions
• Measuring the real-time stages
• General theory
– structures
– control processes
• Representation
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definition
content vs. code
analog and analyic
types of codes
multiple, isolable, codes and their co-ordination
Assumptions
• Mental events are a series of real-time events
• The stimulus undergoes changes in representation
• There is a limited capacity at various stages
Mental Chronometry
• Measuring the duration of mental events
• time is measured in milliseconds 1/1,000 of a
second
• Donder’s subtraction method
– Simple RT
– Choice RT
Simple RT
• Sum duration of three basic processes
– stimulus encoding
– central processing
– motor response time
Choice RT
• Measure the time of an added stage
– add a new step onto the simple RT and by subtraction measure the
duration of the new step
• e.g.
– choice = discriminate between two stimuli, red and green, circle or
square
– choice = time to select one of several motor responses
General Theory
• “Mind” is divided into structures and processes
• Structures (components of memory)
– sensory register
– working memory (STM)
– LTM
• Control Processes
– voluntary -conscious and unconscious
– automatic - unconscious
General Theory
• All people are assumed to have the same
structures
• Individual, cultural, and developmental
differences are assumed to be an aspect of the
control processes
Representation
• Code - must be able to translate between the
code and what it stands for
– e.g. buying clothes from a catalog, can’t see actual clothing but
given several types of representations (picture, written description)
Content vs Code
• Same info can be represented in different codes.
• The “best” code depends on the use of the info
– e.g. “a picture is worth a thousand words”, but not over the phone
– STM preference for acoustic codes
Analog and Analytic Codes
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Analog e.g. map or picture
resembles
2nd order isomorphism
detailed to abstract
continuous
properties similar to
perception
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Analytic e.g. language
not resemble
arbitrary association
needs set of rules for
construction and
transformations
discrete
propositions
concepts without language
equivalents
unconscious repres
Types of codes
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Visual, image, physical, iconic
auditory, acoustic, phonetic, echoic
semantic, meaning, propositional
touch, taste, and smell - all sensory systems
produce a code
• motor code - motor program
– not require attention
– riding a bike
– skilled typist- motor but not visualcode
Multiple Isolable codes and their
co-ordination
• Every time you are exposed to a stimulus - ALL
the relevant codes are activated
• Parallel processing - all codes are activated at the
same time, however, there is serial processing
within a code
• Temporal Hiearachy
– speed of processing
• Race Horse Model
– simultaneous matching
– successive matching
Temporal Hierarchy
• Posner’s letter matching task
– observers are presented with pairs of letters
– 3 conditions (instructions) for responding same
• physically identical (A A)
• same name (A a)
• same semantic category - vowels or consonants (a e)
– results (RT) in milliseconds
• physical (A A) 549 ms
• name
(A a) 623 ms
• semantic (A e) 699 ms
Temporal Hierarchy
• “temporal hierarchy” refers to
– physical faster than name faster than semantic
• Further results support differences in processing
speed
– In semantic task AA is 70-100 ms faster than Aa. The 70-100ms is
the time needed to complete name compared to physical
– In physical task saying “no” to Aa is same as Ac - there is no
interference of the name (you can answer before name code is
finished
Temporal Hierarchy
– In name match - slow to say “no” to EF because get interference
from the quickly processed physical similarity
Race Horse Model
• All codes start at the same time but take different
amounts of time to finish processing
• evidence to support this model is based on idea
that codes are isolable - sufficiently separate that
we can independently manipulate their time
course ( influence the duration of one while
leaving the others alone).
Simultaneous matching
• Both letters are presented at the same time
• manipulate irrelevant physical features to interfere with the
physical match, but not influence the name match
Corcoran & Besner (1975) - manipulating size and contrast affects physical match more than
name match
e.g. size =
Factor
None
Size
Contrast
Both
B
B
physical
510
534
536
560
contrast = B B
name
565
575
581
578
Simultaneous matching
• Cooper and Shepard (1973)
– rotate one of the letters
– physical RT = 610; name RT = 570
– know name before finish rotation
• Pachella & Miller (1976)
– manipulate physical intensity and relative frequency.
– Physical intensity should influence physical code
– relative frequency should influence name code
Successive matching
• Present letters one at a time, remove first before
presenting second
• What is the fate of the stored code of the first
letter?
• Posner -present first letter then vary the delay
(ISI)
– name matches are unaffected
– physical matches show increasing RT with increasing ISI (acoustic
recoding)
Successive matching
• Thorston et al - Visually and acoustically
confusing letter pairs
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visually confusing - RP, EF
acoustically confusing - TP, BG
plot RT to the “different” response
with increasing time acoustic recoding interferes with the
acoustically similar pairs, but helps with the visually similar pairs