cognitive Flashcards
armchair psychology and locke
not based on science, rather logic, reasoning and talking of the environment
the mind is learnt not made
empiricism
founding of experimental psychology
founder is wundt
founded the 1st psych lab in leipzig- 1879
mind/behaviour can be studied as a science empirically
favoured introspectionism
what is introspectionism?
-controlled lab conditions allow one to gather info into how minds work
-training people to carefully and objectively as possible
analyse the content of their own thoughts
-trained observers were presented with carefully controlled sensory events, and asked to describe their mental experiences of these events
-repeated experiments should generate the same results →
replicability of findings
brass instrument psychology- wundtian experimentation
COMPLICATION CLOCK APPARATUS
participants do two things at the same time: observe the rotating clock, AND report the time when a bell rings
the delay between the actual and the
reported time will indicate the speed of
attention
concluded that individuals are unable to focus on two thoughts at the same time, taking roughly 0.1 seconds to change from one thought to another
what are the problems with the introspective method?
- is it really science?reports not always reliable; possible biases
- many interesting mental activities (learning, personality, development, etc.) are
not transparent to introspection - impossible to study young children and animals
what is behaviourism?
dominated psychology for much of 1st half of 20th century
central idea: everything that organisms do (including acting, thinking and feeling) can and should be regarded as behaviours
if we want to have a science of mind, only overt behaviour can be
scientifically studied
most (perhaps all) types of behaviour are learned rather than innate
radical empiricism
pavlov’s dogs
classical conditioning
tudied establishment and extinction of “conditional reflexes” (e.g., salivation) that only occurred conditionally upon specific previous experiences of the animal (e.g., sound of a bell)
operant (instrumental) conditioning
animal is instrumental in trying to change their environment
behaviour is learnt to manipulate environment
originally demonstrated by thorndike with cats
what is the law of effect?
good outcome=repeat action
bad outcome=avoid repeating action
skinner’s box
controlled environment allows systematic study
of how to modify behaviour – via
reinforcement (food) or punishment (electric shock)
for instance: is occasional (“partial”)
negative or positive reinforcement more effective than constant reinforcement, or less?
also invented box for children- air cribs
the mind according to behaviourism
not accessible to investigation
“black box”: scientists can only observe stimuli and responses – internal structure
of the mind is opaque
chomsky vs behaviourism
in 1959, published devastating criticism of behaviourist approach
language is rapidly learned by all children, with only minor variation (“poverty
of stimulus”)
human language has syntax (“colourless green ideas sleep furiously” – we
recognise well-formed syntax even though it makes no sense)
language according to chomsky
language has rich internal syntactic structure which is rapidly acquired by children – some of it is likely innate
hence we need symbols and rules
* words stand for some referent (symbolic), have mental
representation
* words combine into sentences according to syntactic rules
the mind as an information processing device
the mind according to cognitive psychology can be conceptualised
as an information processing device: note: does not imply that the mind is literally a computer (merely that it performs computational functions)
experimental studies
mental chronometry– measuring the
time that a mental process takes to be
carried out
pioneered by donders in the 19th century
(schmidgen, 2005)
statistical inference
p (or probability) value: probability of obtaining the result (or more
extreme) assuming that the null hypothesis is true (i.e., there is no
underlying effect)
the smaller the p value, the better (the stronger the evidence that a
given finding is not due to chance)
convention for most of life/social sciences: p ≤ .05 (less than 5%)
indicates ‘statistical significance
acquired brain damage
cardiovascular accidents (stroke)
trauma/injuries (e.g., traffic accidents, gunshot wounds etc.)
tumours
encephalitis
neurosurgery (!)
dementia
“ablation” in animal research
what is graceful degradation?
brain is to some extent protected against
total wreckage
selectivity of cognitive impairment
the more selective a cognitive impairment (i.e., the more specifically a particular cognitive domain is impaired while others are spared), the more informative the case is for cognitive science
neuropsychological impairments
agnosia – loss of ability to recognise objects (despite vision being intact)
prosopagnosia – inability to recognise
faces (but objects can be recognised)
aphasia – specific language impairment
(in the absence of intellectual
impairment)
amusia – deficit in musical pitch
processing, music memory and
recognition (but auditory system is
intact)
single and double dissociation
single= individuals suffering from ‘broca’s aphasia’: can
understand language but no longer able to produce it
double=patient suffering from ‘wernicke’s aphasia’ can produce fluent speech, but has trouble comprehending utterances
what is sensation?
detection of simple properties (e.g brightness, colour, loudness, sweetness)
what is perception?
interpretation of sensory signals (e.g object recognition, identification of properties such as location, size, movement)
how does the brain receive signals of the external world?
relies on signals received from sense organs (eyes, ears, skin, etc.) via afferent (incoming) nerves
what do sensory systems require?
a biological mechanism for translating physical attributes into electrical
signals (receptors)
mechanism for conveying this information to CNS
detection of light- vision
receptors in the retina of the eye are rods and cones – modified neurons containing photosensitive pigment (rhodopsin)
rods function at low light levels, cones in bright light
cones are colour-tuned – peak sensitivity to either red, green or blue (different rhodopsins)
perception of colour
white light is a mix of all visible wavelengths, all at the same intensity
white is therefore coded as equal output of red, green, blue receptors
single-cell recording (hubel and wiesel, 1962)
electro-physiological response of a single neuron can be observed by inserting a
microelectrode (“single-cell recording”)
retinal complexity
retina contains around 120 million rods and 7 million cones, richly
interconnected
optic nerve is formed from axons of approximately one million ganglion cells
structure of the retina
- network of connections between receptors and optic nerve performs local
computations - response of photoreceptors and bipolar cells to illumination is graded
- amacrine cells and horizontal cells combine and contrast signals from adjacent photoreceptors
- ganglion cells generate action potentials and form the optic nerve
feature detection- neurophysiological evidence
electrical responses monitored in a single cell when bright lines in different orientations are projected onto a small area of the retina (selective and specific)
particular cells are selectively active in response to a particular stimulus (say, a line)
in a particular orientation (e.g., vertical) – “feature detectors
early processing of visual information
interconnections mean that retina does not function as a simple light detector
retinal processing involves ‘cleaning up’ of image and beginnings of feature extraction
input ultimately feeds into the visual cortex
visual cortex is itself
hierarchically organised
separate structures exist in visual cortex for extracting information about shape, colour, position, motion, etc
cortical processing of visual information
feature processing structures in visual cortex arranged in layers
early stages of processing detect elementary visual features - ‘simple cells’
discovered by hubel and wiesel in the 1960s (nobel prize in 1981) via singlecell recordings from neurons in visual cortex
collections of ‘simple cells’, each responding to a line or edge in illumination reaching
a particular region in the retina
perception description
involves interpretation of sensory input as information about an external world
requires computational processing of sensory data, including
segmentation and object recognition
construction of 3-dimensional representation
many of the processes involved in this are automatic and/or innately determined
interpretation is an integral part of our sensory experience, with limited awareness of “raw” sensory input
what are the groups according to gestalt principles?
similarity, good figure, proximity and connectedness
segmentation (parsing) of the visual scene
first stage of object
recognition – visual
features that belong to
the same object are
grouped together
figure-ground
perception - a
prerequisite for object
recognition (applies to
all objects in visual field) assignment of figure and ground can be ambiguous (as in the ‘rubin vase’) but distinction must always be made
gestalt principles of grouping (e.g wertheimer 1923)
grouping of elements to make a “figure” is determined by a set of basic principles that are automatic, and innate (evidence from studies of infants)
the necker cube
demonstrates that we automatically construct a 3-D world from a two dimensional image
an ambiguous figure – yellow in front of blue, or vice versa?
either interpretation is possible, but at any given moment, must be one or the other (not both)
cues to depth perception
relative height
relative size
perspective convergence
texture gradient
innate depth perception evidence
the visual cliff- gibson and walk (1960) apparatus for testing whether animals or infants are able to interpret these kinds of depth cues
the visual cliff findings
gibson & walk (1960) tested 36 infants old enough to crawl (6 –
14 mths)
27 were willing to move onto the shallow side, but only 3 onto
the deep side
visual cliff findings on animals
when placed on the deep side, a one-day old goat jumps to the safety of the
start board
for some animals, depth perception appears to be innate
perceptual constancy
the brain generates an interpretation of the (often ambiguous) input
our brains implicitly assume that objects are stable and unchanging (“perceptual constancy”)
the brain automatically computes “true” size, shape etc. of objects by
taking into account viewing conditions
examples of effortless recognition of perceptual information
identifying objects or faces
reading printed words
understanding speech
testing the speed of written word recognition
spritz
reading passages one word at a time (centrally presented)
with 400 words per minute, there are about 7 words per second, or approx. 140 ms per word
at top speed (700wpm) there are about 12 words per second, or
approx. 85 ms processing time per word
template theories (e.g neisser 1967)
when we recognise something, we match it up with the closest
instance (‘template’) of things stored in our memory
pattern recognition is based on global similarity match between sensory input and templates stored in memory; best match is output of recognition process
what is an example of a template theory?
letter recognition
machine recognition and template theories
theory is intuitive and computationally simple
this works for some machine recognition systems like bar code readers or automated plate recognition
variability of real input
people write numbers differently (e.g 7)
therefore we ignore percetual variability and recognise the numbers successfully modified national institute of standards and technology database for
machine learning made for handwritten digits
difficulties with template theories- letters
vompleteness issue (“R” recognised as “P”?), position, rotation, slant, size, differences in font etc.
could be partially resolved by preprocessing (“normalisation”) of the visual image
but problematic for handwriting
difficulties with template theories- complex objects
needs to be able to deal with changes in viewpoint, quantification of
“similarity”
template matching evaluation
works in some (often quite restricted like number plates) environments
but probably not promising as a general theory of human pattern recognition
feature matching theories
pattern recognition is based on identification of features in the visual
array
“features” are fragments or elementary components of a larger pattern
for recognition purposes, objects can be defined in terms of their component features, e.g. the letter A consists of two slashes and a dash
advantage of feature matching
a limited number of features can be used to represent a very large number of objects
features should be efficient (gibson, 1969):
should discriminate effectively between possible alternatives,
with a minimal feature set (feature set of capital letters)
low-level visual feature analysis
hubel and wiesel (1962) conducted
single cell recording in the visual cortex of anaesthetised cats
specific cells respond only to certain kinds of stimuli (e.g., a line,
at particular width, at particular angle, located in the right position)
– simple feature detectors are
“wired in”
disadvantages of feature matching theories
is feature extraction feasible for complex object recognition?
how to describe a cat (or some other object) in terms of low-level visual features?
viewpoints and object representations
one potential problem is that both template- and feature matching
theories assume that objects are stored in a viewer-centred
representation (“what it looks like”)
viewer centred
potential solutions to viewpoints and object representations disadvantages
represent objects in objectcentred fashion:
* object is perceived in a coordinate system centered on
the object, not the viewer
* brain aligns a reference frame,
using object’s axes of elongation and symmetry
* uses that reference frame to measure relative positions of
object components
recognition by components (biederman 1987)
objects can be described in terms of small set of
geometrical parts named geons - about 24
geons are simple 3D shapes: cylinders, cones, wedges,
etc., each in ~15 sizes and builds
how could objects be represented by geons?
mental representation of an object consists of array of constituent
geons, along with description of spatial relations among them
(“attachment relations”)
many everyday objects can be built out of 2 or 3 geons
geons
few geons and “attachment relations” can be combined into an astronomical number of objects:
24 geons x 15 sizes/builds x 81 ways to join them = 10,497,600
possible objects
many everyday objects can be built out of two or three geons into
instantly recognisable shapes
demands on the visual system are not unrealistic: object recognition implies carving up objects into shapes, and ascertaining their
arrangement
evidence from behavioural studies (biederman 1987)
if object recognition critically relies on
attachments between geons, then deleting info about attachments should make recognition more difficult
brief (100 msec) presentation of
images with 65% deletion of contour:
(A) deletion from middles of segments,
(less diagnostic of geon structure)
(B) deletion at vertices (critical for identifying geon structure)
*correctly identified objects:
* condition A: 70%
* condition B: 45%
vertices (which provide info about geon structure) seem indeed critical for
object recognition
limitations of geon theory
difficult to distinguish between objects with identical (or very similar) geon structure, e.g., horse and cow?
recognition of specific individuals (e.g., faces) - if there is a generic
geon construct of face, how does the visual system distinguish between different faces?
works well for artefacts, but less so for natural objects (mountains, trees, etc.) – what is the geon representation of a puddle?
how do machines tackle recognition problems?
- “big data” – internet provides massive amount of instances on which machines can be trained
- “deep learning” – a novel type of neural networks which show much improved performance compared to previous generations
face inversion (yin 1969)
faces are more difficult to identify when upside down than when right
side up
the thatcher illusion (thompson 1980)
- we process faces using local features (e.g., nose, eyes, etc.) and most importantly, their configurations
- when faces are inverted, only local features are available – which are not very dissimilar between normal and inverted view
- but when the faces are right-side-up, we can process the configural information as well, and so the inverted mouth and eyes look odd
what is rubin vase an example of?
a reversible figure-ground relationship
fMRIs and rubin vase
when people are seeing the rubin image as a face, there is greater activity in the face-selective region of the temporal lobe than when they are seeing it as a vase
image-based object recognition theories and templates
an object you have seen before is stored in memory as a mental representation that can be directly compared to a viewed shape in the retinal image
what is part-based object recognition?
the brain deconstructs viewed objects into a collection of parts
objects are stored in memory as structural descriptions: metal inventories of object parts along with the spatial relations among those parts
dichotic listening task
- two different messages are transmitted to the two ears
- participant is asked to “shadow” one of the messages while ignoring the other
- after a particular episode/trial, s/he can be asked questions about the unattended information
dichotic listening- cherry (1953)
participants almost entirely unaware of information presented to the
unattended ear:
* knew whether or not a voice was presented
* could report physical attributes of the voice (e.g., gender of the
speaker, etc.)
* knew very little about the content of the message
* unable to report the language
what does cherry (1953) suggest about dichotic listening?
information in the unattended message is processed only
to a very “shallow” degree
broadbent’s filter model (1958)
- “chunks” of sensorial information are
represented as balls - attentional selection symbolised as Y shaped tube through which information
must pass - information enters through sensory
channels and is filtered as it proceeds - tube accepts only one ball at a time, with
hinged flap acting as a filter
moray (1959) contrast to the filter model
reported a surprising finding: participants able to report if their name is presented on the unattended channel
this lead to the development of the cocktail party phenomenon
such effects of “high priority” appear problematic for static filter model such as broadbent’s
what is the cocktail party phenomenon?
highly pertinent stimuli (such as one’s
name) can suddenly capture one’s attention in a noisy environmen
treisman (1960)
- fragments from unattended channel are occasionally reported if they are
congruent with the context of the attended message - implies that unattended information must have been processed to certain extent
treisman’s (1960) attenuation model
unattended information is not
entirely blocked (as e.g., in broadbent’s model)
instead, attention acts as a selective filter
first step of the attenuation model
physical properties of
sensory information are analysed
(voice, etc.)
second step of attenuation model
knowledge about words is accessed (“mental lexicon”)
entries in the mental lexicon are stored in terms of frequency of occurrence,
relevance, etc. (“permanent
priorities”), and have varying recognition thresholds
how can thresholds be temporarily lowered in the attenuation model?
expectations (“current
priorities”)
how is meaning analysed in the attenuation model?
if the signal passes both filters
cocktail party effect and attenuation model
- one’s own name has high relevance, and frequency of occurrence, in
one’s mental life - corresponding entry in the mental dictionary has high permanent priority (i.e., low threshold)
- occurrence of name on the unattended channel likely to be noticed and result in the appropriate action
explanation of triesnman (1960) results
expectations can temporarily lower the thresholds of words in mental dictionary
hence, fragments of unattended information will sometimes access
meaning if they fit into the context of the attended message
early selection theories of attention
attentional bottleneck always (broadbent) or typically (treisman) occurs before the stage of pattern recognition
unattended stimuli can only be processed if attention is switched
(broadbent), or recognition threshold of information is low (treisman)
unattended information is usually not (treisman) or never (broadbent) processed to the level of meaning
late selevtion theories (e.g deutsch and deutsch 1963)
provocative claim: selection of information regarding conscious awareness occurs only after analysis of meaning
claim: contrary to theories outlined so far, all sensorial information is
always processed nonselectively and in parallel, up to the level of meaning (!)
output of sensorial processing is placed in short-term memory
information in STM is quickly lost, and this loss acts as “attentional
bottleneck
evidence for late selection: subliminal perception
“trial”: a single experimental episode/instance, with an experiment being formed by many trials
very briefly presented words are semantically processed and might affect (i.e., they “prime”) processing speed of subsequent, semantically related
target words (e.g., marcel, 1983)
evidence for late selection- negative priming
display with two dimensions is presented
participants are instructed to attend to one dimension, and ignore the other
for instance (allport et al.,1985): name red picture, ignore
green picture. time it takes to name the target is measured with voice-activated trigger
negative priming p2
on critical trials, average naming times to the target (i.e., red) object are slower if ignored on the previous (N-1) trial (compared to an
unrelated condition)
“negative priming”: ignoring a stimulus slows down subsequent
redirecting of attention to that stimulus
suggests that ignored information is not simply discarded, but is
actively suppressed
…implies that processing of non-attended information is deeper than
assumed by ‘early selection’ theories
kahneman (1973) capacity theory
inability to perform two tasks at once is not the result of built-in
attentional bottleneck (early, late, etc.)
rather, people have limited-capacity pool of attention to carry out
mental activities
if an activity is easy, very little attentional capacity is used up
if an activity is difficult, it uses up all or most of resources
how much capacity is available at any given moment?
depends on:
* task demands (some activities are more demanding than others)
* arousal (determined by alertness, circadian rhythm, medication,
etc.)
* individual
differences/dispositions (some individuals are better
than others in paying attention)
* momentary intentions (how important it is to you)
what is allocation policy- kahneman?
individuals have substantial control
over how they allocate their attention…
…but performance will decline if attentional demand exceeds sup
how do we put capacity theory of attention to the test?
doing multiple things at once
dual-task experiment: individuals carry out two activities at once, and we measure the impact of one task on performance on the other
if the two activities share attentional capacity, then one task should affect the other (increasing demand on task 1 should impair
performance on task 2, etc.)
johnston and heinz (1978)
primary task – a light flashes repeatedly and at random intervals, and participants press a button as quickly as possible when they detect it
secondary task – at the same time, individuals “shadow” words
simultaneously presented to both ears, either
* by simple repetition (i.e., identical message was delivered to both
ears) - EASY
* according to physical category (“shadow what the female voice
said”) - HARDER
* according to semantic category (“shadow the word that is a city”) –
HARDEST
if speed of detecting the randomly flashing light (primary task) is
affected by difficulty of shadowing (secondary task), then both tasks
draw on a shared attentional pool
johnston and heinz (1978) part 2
response times to detect flashing light were
* fastest when participants simply shadowed the message (“one list”
condition)
* slower when participants shadowed according to physical criterion
* slowest when participants shadowed according to semantic criterion
johnston and heinz (1978) reaction time cost
the difference between single-task responding to light (without any
shadowing), and the dual task situation
johnston and heinz (1978) findings
selective attention requires capacity
early selection mode (physical condition) requires less capacity than late selection mode (semantic condition)
attention comes at a cost!
automaticity
complex activities are initially intensely attention-demanding
with increasing skill, performance acquires more automatic
processing mode
shift from attention-demanding to automatic mode of processing occurs through practice
automatic vs unconscious processing
posner & snyder (1975): mental processes can generally be divided
into automatic and conscious/controlled
automatic processing (posner and synder)
the process occurs without intention, without a conscious
decision
not open to conscious awareness or
introspection
consumes few if any conscious resources; i.e., it consumes little if
any conscious attention
operates very rapidly, usually within 1 sec
conscious processing (posner and synder)
the process occurs only with intention, with a deliberate decision
is open to awareness and introspection
uses conscious resources; i.e., drains
the pool of conscious attentional capacity
is slow, taking more than a second
or two for completion
stroop task (1935)
massive degree of interference when the word miscues responses
stroop conflict
ignored dimension (in this case, reading of the word) is
* highly practiced and overlearned
* unintentionally and automatically processed to high level without demanding mental capacities
target dimension (here, naming of colours)
* less automatic, and requires more effort
* Incompatible information between dimensions creates conflict
* conflict resolution requires effort and takes time (and leads to potential errors)
variants of stroop- picture word interference
name the picture, ignore the word (e.g., rayner & posnansky, 1978)
slower object naming times if distracter word is related in meaning to the object than when it is unrelated
what is STM good for?
any complex tasks appear to require short-term storage (buffering) of information
e.g:
1. arithmetic
2. language (trump thought that he won the election” – how
do we know what “he” referred to presumably, trump is
temporarily “buffered” in STM
3. vision- navigation in space
miller (1956) the magical number 7(+/-2)
inidividuals can hold ~7 simultaneous items in the STM
capacity is largely dependent on the nature of items (e.g digits, letters and words)
capacity is less than 7 items for items that dont mean anything (e,g nonsense words)
if possible, short-term memory makes contact with representations
which are permanently stored in our minds
digit span task
common component of many IQ tests, including the widely used wechsler adult intelligence scale (WAIS)
* screening test for clinical impairments (e.g., dementia)
* read out three digits (3, 1, 4) in a monotonous voice, with one digit read per second
* if correctly recalled, increase to four digits (7, 3, 5, 1)
* if correctly recalled, increase to five, etc. (in a clinical setting, task is
often stopped after five digits)
superspan lists (less than perfect performance)
present lists of items longer than max. capacity of STM (~7)
* free recall task: recall the list of items, in any order
* across many trials, plot average recall probability (y-axis) dependent on list
position (x-axis)
what is the primacy effect (serial position curve)?
reflects contribution of LTM (earlier items undergo more
rehearsal)
what is the recency effect (serial position curve?
reflects contribution of
STM (items that are
still active in ST store are recalled
better)
post-list distractor items and SPE
glanzer and cunitz (1966) - if recency effect is due to STM, it
should be eliminated if participants perform irrelevant distractor
task after list (but before recall)
- ppts count for either 10 or 30 seconds after list presentation (or immediately)
- recent effect visible in baseline (0 second) condition and it virtually eliminated by post-distractor items
HM case study (milner 1966)
suffered from intractable epilepsy
part of his temporal lobes surgically
removed, including hippocampus
showed defective LTM learning: inability to acquire new information post surgery (“anterograde amnesia”)
but had normal STM
double dissociation between STM and LTM- KF (shallice and warrington 1970)
brain damage following motorbike accident
LTM performance in normal range (learning of word pairs, lists of words, etc.)
STM dramatically impaired: usual digit span of 7±2 reduced to max. 2
neuropsychological evidence suggests that STM and LTM are separate memory systems
modal model of memory (e.g atkinson and shiffrin 1968 MSM)
for information to enter LTM, it must pass through STM
STM has limited capacity of about seven or so items
information can be ‘refreshed’ in STM by means of rehearsal
the longer an item held in STM, the more likely to be transferred to LTM
baddeley and hitch (1974) question and study proposal
question: if STM is so essential for everyday activities, why isn’t such a dramatically
reduced STM capacity more detrimental?
role of STM could be tested by
* assessing unimpaired individuals on a fairly challenging primary task
* simultaneously occupy their STM system with a second
(‘concurrent’) task
* see how much this affects performance on the primary task
acording to the ‘modal model of memory’, this should catastrophically
affect performance
baddeley and hitch (1974) effects of concurrent load
reasoning task – participants asked to verify sentences that
describe two successive letters (e.g A follows B, true or false)
concurrently, were asked to remember list of random digits,
varying in length between 0 and 8
items
if STM is central for reasoning, effect on reasoning task should be catastrophic
baddeley and hitch (1974) results
performance is adversely affected by
concurrent load (reasoning time rises
with increasing list length – 35%)
…but overall performance still
surprisingly good
implication: perhaps STM is not as central to complex tasks such as
reasoning as previously assumed?
working memory model (baddeley and hitch 1974)
STM consists of more than one component
* central executive: integrates information. “amodal” (not tied to a
particular type of code; language, vision, etc.).
supplemented by two “peripheral” systems which are ‘modality specific’:
* visuo-spatial sketchpad: STM
store for the
manipulation of
visual and spatial
information
* phonological loop: STM store for speechbased codes
working memory model explanation of phonological loop part 1
earlier research (digit/letter/word retention; superspan lists, etc.) primarily explored the phonological loop component
multiple components view explains why neuropsychological patients with reduced digit span still function well in most everyday activities – phonological loop is impaired, but other components of WM are still
intact
also explains results from Baddeley & Hitch: digit retention fills up the phonological loop, but the primary reasoning task can be carried out based on the other components
working memory model explanation of central executive part 1
- “mental workbench” - retrieves information from LTM and allows
subsequent manipulation - regulates information flow between the other components of WM
(visual and phonological), - “amodal” - not tied to specific modality (verbal, visual, tactile, etc.)
- constrained by available capacity - the more demands are placed on the system, the less efficient it will perform
working memory model explanation of central executive part 2
“central executive” in the B&H model is the way in which we negotiate various, often competing, demands and habits (“cognitive control”, or
“executive function”)
instances of when cognitive control breaks down - patients with frontal lobe damage, resulting in repetitive performing of the same act, or
making the same mistake over and over again
working memory model explanation of visuo-spatial sketchpad part 1
- specialises in the temporary holding and processing of visual and
spatial codes - remembering shapes and colours; tracking moving objects in space; planning spatial movements and navigating environment
working memory model explanation of visuo-spatial sketchpad part 1
spatial task (corsi blocks test): experimenter taps out random sequence on blocks, participants attempt to reproduce sequence (typical span ~5)
some neuropsychological patients exhibit severe impairment in tasks of
this type while showing normal recall of verbal items (e.g., Hanley et al., 1991)
working memory model explanation of phonological loop part 2
specialises in the storage of speech-based code
more-or-less corresponds to what had been traditionally studied in STM research (e.g. digit span tasks, serial position curves, etc.)
phonological loop has severely restricted capacity (perhaps seven items)
word length effect (baddeley et al 1975)
STM performance is better for shorter than for longer words e.g wit and sum compared to words like university and opportunity
debates in the capacity of STM
tradition= 7+/-2, STM is limited by fixed number of items
revised, time-based, view (baddeley et al., 1975):
* no inherent (built-in) limitation of the PL capacity
* rather, STM capacity is constrained by the time it takes to report
the items
* measured capacity is determined by number of items that can
be reported before they are lost from the phonological loop
baddeley et al (1975) syllables
presented five-word lists, words ranging in length from 1 to 5 syllables
participants either recalled the lists or read them out aloud
STM recall: short
words better recalled
than long words
(word length effect)
Reading speed: short
words take less time
to read than long
words
amount of items correctly recalled (i.e., 90% or higher accuracy) is not 7, but
whatever can be uttered in about 2 seconds
concepts- the classical view (plato, locke etc)
intuitive view that most things should be definable by their properties
concepts can be defined by an exhaustive list of necessary and
sufficient semantic features: cat (whiskers, purrs, 4 legs)
central notion – mental representations of concepts are composed of
lists of semantic features which jointly determine category
membership
difficulties with the classical view of concepts
- very difficult to come up with an exhaustive list of features for a
given concept - what are the features of “birdness” which include every instance
of a bird but exclude every instance of something not a bird? - e.g., most birds sing but some don’t; most birds fly but some don’t; birds typically nest in trees but some don’t, etc.
family resemblance (rosch, 1973)- contrasts classical concepts
- all family members seem to resemble each other
- dark hair, moustache, glasses, big nose, big ears are typical of the family
- but none of the members have all features
family resemblance (rosch, 1973) prototypes
perhaps we mentally represent the characteristics of this family by an average of all its members?
number 9 (the one with all properties of the family) constitutes a ‘mental prototype’
– but may not exist in reality at all
prototypes (rosch, 1973)
we organise our mental representations of a conceptual category around the average of the various instances which we are familiar with
instances have graded membership – some members are closer to
the prototype than others
conceptual categories have fuzzy boundaries – there are no clear
dividing lines which would indicate membership (classical view doesn’t work)
how do we measure typicality effects?
sentence verification tasks, quickly deciding if a statement is true or false (e.g a tomato is a fruit)
typicality ratings
strong agreement among raters regarding typicality of category instances (e.g., rosch, 1975):
fruit (1-7, 1 being highest)
apple 1.3
plum 2.3
pineapple 2.3
strawberry 2.3
fig 4.7
olive 6.2
verification speeds depends on typicality…
as a general observation, one can say that whenever a task requires someone to relate an item to a category, the item’s typicality influences performance” (murphy, 2002)
prototype theory of concepts
what happens when we make a category judgement on a new
instance (is this a dog?)
we compare it to a mental representation of a prototype
exemplar theory of concepts (medin and schaffer, 1978)
contrasts prototype theory
we do not compare the new instance to a prototype
rather we compare it with stored instances of all other members of the category
prototypes vs exemplars
typicality effects (“is apple a fruit” vs. “is fig a fruit?”)
- prototype theory: “apple” is much more similar to a prototypical
fruit than “fig”
- exemplar theory: “apple” is encountered more often than “fig”
and hence instances are retrieved faster
graded membership (“is dog a mammal” vs. “is whale a mammal”?)
- prototype theory: “dog” is close to a prototypical mammal but “whale” is very far
- exemplar theory: “dog” is encountered more often than “whale”
neurology of prototypes and exemplars (both exist)
some evidence ashby & ell, 2001) from
neuroimaging as well as from acquired brain damage that the brain
might use both prototypes and exemplar-based strategies when
categorising instances:
* visual cortex: involves prototypical mental representations
* prefrontal cortex and basal ganglia: involved in learning exemplars
so perhaps visual cortex involves more ‘holistic’ processing
(prototypes) whereas prefrontal cortex, involved in decision
making, uses explicit instances/exemplars
category-specific deficits
no such patients with really narrow deficits (e.g only doesnt know fruits)
some neuropsychological patients present with deficits in semantic
understanding which are specific to a given category
- e.g., warrington & mccarthy (1983): patient had normal knowledge of living things, but was selectively impaired on human-made objects
- e.g warrington & shallice (1984): patient with intact knowledge about human-made objects but impaired insight into living things
- semantic dementia= gradual decay of knowledge about world
what are the categories of category-specific deficits
capitini et al (2003)
animate objects
inanimate biological objects (e.g nature)
artefacts
homo ecomomicus/economic person
economics – discipline which explores how people interact when they exchange goods and services
common assumption: humans act as perfectly rational agents which maximise their utility for both monetary and non-monetary gainse
homo economicus=imagined person which has
an infinite ability to make rational decisions
behavioural economics
studies the effects of psychological, cognitive, emotional, cultural and
social factors on the decisions of individuals and institutions
kahneman and tversky: compared cognitive models of decisionmaking under risk and uncertainty to economic models of rational behaviour
rationality, heuristics and biases
in many situations, we operate under uncertainty when making decisions (should I buy this house? should I marry this person? should I
apply for this job? etc.)
in many situations, it would be difficult and laborious to work through all the options to make a ‘rational’ decision (which of these three flats
should i rent?) – slow and effortful
- in cases such as these, people often apply heuristics
* heuristics: mental shortcuts, or ‘rules of thumb’ which are often
effective when having to make a decision (fast), but also…
* often wrong, leading to biases, or tendencies in which our decision
making violates “pure” rationality – a ‘thinking error’ (kahneman) or
‘mind bug’ (schacter et al.)
what is availability bias?
probability estimate of occurrence is judged by its availability in memory e.g what is the risk of being killed in an airplane accident vs being killed in a car accident?
availability bias- real life examples (gigerenzer, 2004)
following 9/11, many americans switched from air to road travel
“the number of americans who lost their lives on the road by avoiding the risk of flying was higher than the total number of passengers killed on
the four fatal flights” (gigerenzer, 2004)
real life applications of availability bias
when ‘nudging’ individuals away from
risky and towards healthy behaviour – more useful to provide them with vivid examples than with objective information
conjunction fallacy example
linda is 31 years old, single, outspoken, and very bright. she majored in philosophy. as a student, she was deeply concerned with issues of discrimination and social justice, and also participated in anti-nuclear demonstrations.
which is more probable?
1) linda is a bank teller.
2) linda is a bank teller and is active in the feminist movement
human participants consistently choose 2) over 1) (tversky &
kahneman, 1983)
tversky &
kahneman, 1983 explanation of ‘linda’ conjunction fallacy
probability of linda being a bank teller (answer 1)
probability of linda being a feminist
joint probability of linda being a bank teller and a feminist
(answer 2) – must logically be smaller than 1)
combined probability of two events is always less than the independent probability of each event
yet people tend to believe that two events are more likely to occur together than either individual event
semantic component of STM
patients have been identified who cannot repeat more than 1-2 words/numbers in a STM task but can speak normally in conversations
when asked to repeat sentences verbatim they paraphrase
suggests poor phonological STM, but good semantic STM that can store the gist of a sentence for a short time
name one important function of STM
convert information into LTM (e.g phonological STM to phonological LTM)
what is phonological LTM?
supports our ability to identify spoken words
no meaning associated with phonological LTMs
phonological STM patients have difficulty learning new words in LTM=good predictor of literacy in children is nonword repetition
what is visual LTM?
supports out ability to identify visual information, including written words, objects, faces, etc
what is semantic LTM?
our knowledge of the meaning and function of words and objects. semantic memory supports inferences i.e., an ostrich breathes
what do semantic deficits lead to:
- difficulty in learning new concepts
- problems in understanding and producing complex meaningful sentences
what is episodic memory?
links memories from various LTM systems
to store a record of a personal event
what is procedural memory?
motor skills
learning skills over many trials (even amnesic patients (including famous patient HM)
evidence for different LTM systems comes from…
dissociations
e.g single dissociation: an experimental
manipulation or neurological impairment affects performance on
task 1 more than task 2.
– for example: dyslexics have difficulty
identifying words but are fine in recognizing faces
- suggests that LTMs for words and
faces are stored in different systems,
and that LTMs for words damaged in
dyslexia
double dissociation and LTM
experimental
manipulation or neurological impairment affects performance in
task 2, but not task 1
– for example, prosopagnosic patients
have more difficulty in identifying faces compared to words
– this rules out difficulty argument!
- much stronger evidence that there
are two types of visual LTM – visual LTM for words and faces
LTM system for sound stimuli can be broken down into:
- pure word deafness: patient cannot understand words but can understand environmental stands (understand “meow” but not “cat”)
- auditory agnosia: can understand spoken words but not environmental words
dissociations between episodic and phonological STM
anterograde amnesic patients (e.g., H.M.) have poor episodic memory and good phonological STM.
phonological STM patients have poor phonological STM but good episodic memory
this does not contradict the view that info is first stored in STM as patients with phonological STM deficits do have difficulties learning new phonological
LTMs but episodic memory can be supported by other STM systems
dissociations between episodic LTM and procedural memory
amnesia selectively impairs episodic
memory. procedural memory is fine.
– example of this single dissociation is
mirror drawing
- parkinson’s and huntington’s
disease selectively impairs procedural learning.
– together, these two sets of results
constitute a double dissociation.
light task performance
form of procedural memory as undergrad students learn with repeated trials- anticipation
this is preserved in amnesiacs
in order to store things in episodic memory you must…
pay attention
craik (1996)
- participants studied word pairs (e.g., window-reason, fun-banana, etc.
- at test, given the first item, attempt to recall the second (cued recall test).
- dividing attention at encoding impairs memory more than at test
what is maintenance rehearsal?
keeping information active in STM by relying on phonological loop (repeating info without considering the meaning)
what is elaboartive rehearsal?
encoding the meaning of to-be-remembered information which generally leads to better episodic memory
levels of processing episodic memory
perceptual<phonological<conceptual
levels of processing: three encoding conditions
case (e.g capital letters)
rhyme
sentence (does it fit in a sentence)
elaborative encoding works best when…
organising new memories to fit with old memories
what is the picture superiority effect?
we encode pictorial information better than verbal information
- ppts studied lists of pictures and words and tested on pictures and words
- asked to attend to the names at encoding (verbal instructions) or the image (imagery instruction)
- tested on pictures and words in yes/no recognition task
what is the concreteness effect?
words like car and house are better remembered than abstract words like truth and betrayal
what do the concreteness effect and picture superiorty effect support?
dual code theory- information store information in at least two forms: verbal/linguistic code and a mental image code
epsiodic memory for visual information can be amazingly good:
- participants studied 2500 images every 3 seconds (over 2 hours of images)
- recalled about 90% of them correctly
brady (2008)
mnemonic devices
mnemonic devices improve memory by
improving the encoding of information
– deep levels of encoding, organising and linking new information to old, visual imagery
method of loci- imagine a journey through a familiar route
then take list of items you want to memorise and link them to the route through imagery
korsakoff amnesia
recall more affected than recognition
kosakoff patients (and with frontal lesions) sometimes suffer from confabulatins as well
moscovitch (1989) confabulation
patient believed he had been married 4 months and had adoprted children in their 30s following frontal system damage
two different ways of retrieving info from episodic memory
- automatic retrieval
- effortful retrieval
automatic retreival
hippocampus can retrieve information relatively automatically with strong retrieval cues:
– in cued recall task part of the study items are repeated at test,
allowing retrieval under divided attention
– in recognition task the study word itself is presented at test,
allowing korsakoff patients to recognize some items
memories often “pop out- these
memories are sometimes correct, sometimes not, and
hippocampus cannot correct itself
weed another system
to correct for false memories
effortful retrieval
if you are not given a strong retrieval cue (as in free recall), then hippocampus cannot retrieve memories very well
– divided attention impairs free recall
– free recall is poor in korsakoff patients
the frontal system can generate better retrieval cues that the hippocampus can use to generate a memory
frontal systems can also monitor and eliminate errors in memory retrieval
the frontal system is the boss of the hippocampal memory…
- control the information that is presented to the
hippocampus at encoding (by directing attention)
– initiate and guide retrieval
– monitor information that is retrieved from hippocampus - analogous to the central executive in the WMM
encoding specificty and retrieval
the effectiveness of a retrieval cue depends on how well it relates to initial encoding.
– that is, the way we perceive and think about events at encoding determines what cues will later
elicit episodic memories
- explains state dependent and mood dependent
episodic memory
context dependent memory (encoding specificty) baddeley 1975
increased retrieval when conditions are the same (WW/DD)
encoding specificty and childhood amnesia
why don’t you remember your first years of life?
a child of 3 remembers what happened
days/months before, so it is not that episodic
memory has not formed yet.
why is smell a good retrieval cue for childhood memories
its because we have a mindset shift of state
encoding specificty and the testing effect
practicing retreival improves memory
encoding specificty and amnesiac
can explain spilt personalities (schacter et al 1989)
what two ways do memories fail?
(1) poor encoding
poor retreival
loss of storage
(2) false memories remembered due to errors in encoding and/or retrieval
memory distortion at encoding (meissner 2001)
various studies have shown that episodic
memory for faces is better for own-race than cross-race (and own-gender, own-age, etc.)
encoding is better for more familiar faces study sangrigoli (2005)
experiment carried out with asian and caucasian participants making perceptual decisions about Asian and Caucasian faces:
–each trial consisted of a target face at the center of the screen for 250 ms, and after 1
second delay, two faces presented side by side.
–participants pressed one of two response buttons to indicate which picture matched the target
findings= french people better at caucasian faces, korean people better at asian faces, adopted french children better at caucasian
therefore familiarty and perception is at play
loftus and palmer (1974)
difference in speed estimates based of critical verb change shows distorion in epsiodic memory due to recall
basic theoretical conclusions from false memories
episodic memory is not like a video
recorder.
– memories can be distorted in various ways at both encoding and retrieval.
* the vary same processes that make memory good (semantic encoding of knowledge at
study; relating to pre-existing knowledge)
contribute to errors
real world implication of false memories
the ability to induce false memories in the
laboratory has led some researchers to claim that recovered memories of traumatic events are false memories and this has impacted the law
the retrieval induced forgetting paradigm
first, participants study words taken two categories:
– FOOD: bread, crackers, peas, ketchup, radish, strawberry…
– ANIMALS: dog, bird, fish, elephant, butterfly, sheep…
second, they further practice a subset of words from
one category:
– ANIMALS: dog, bird, fish, elephant, butterfly, sheep…
at test, participants asked to recall all items from the two categories:
* FOOD, ANIMALS.
finding: memory is worse for the non-practiced words
from the practiced category (animals) compared to words
in the non-practiced category (foods)
nterestingly, over time, the induced forgetting goes away,
so that PR- and NPR items are remembered to the same level
pinker (1994) language acquisition
a language organ is designed through evolution
reading appears to be a learned skill
reading is a recent invention
– no time for evolution
many people around the world are illiterate
rarely acquired without explicit instruction
verbal language may be an instinct…
universal across cultures
brain damage can specifically impair
language. e.g., broca’s aphasia.
rarely a selective disorder of a general skills, e.g., chess.
critical period for language learning
– genie (isolated from language till 13.5 years).
– sign-language.
– phonology (the sounds of language).
bowers et al (2009) preserved implicit knowledge of a forgotten childhood language
native english individuals under age 40 selectively relearned subtle hindi or zulu sound contrasts that they once knew
HE individuals over 40 failed to show any relearning, and young control participants with no previous exposure to hindi or zulu showed no learning
research highlights the lasting impact of early language experience in shaping speech perception, and the value of exposing children to foreign languages even if such exposure does not continue into adulthood
how do we demonstrate that just because something is universal doesnt make it an instinct?
specific deficits occur for cognitive skills that are not an instinct like dyslexia (we have a specific brain region associated with identifying written words- the visual word form area)
hakuata et al (2003) test of the critical period hypothesis for second language acquisition
used responses from 2.3 million immigrants with spanish or chinese language backgrounds
results showed large linear effects for level of education and for age of immigration, but a negligible amount of additional variance was accounted for when the parameters for difference in slope and difference in means were estimated
thus, the pattern of decline in second-language acquisition failed to produce the discontinuity that is an essential hallmark of a critical period
if language evolved then should you not expect something related to human language monkeys or other animals?
pinker in his book “the language instinct”
claims that the absence of language in other species does not challenge the language
instinct hypothesis
wrong conception is that evolution is like a ladder – a progression to more and more
complex organism
Instead, we are very distant cousins to chimpanzees/monkeys with common ancestors, long extinct
best alternative to language as an instinct:
– language is the by-product of increased intelligence
– evolution has played a general role in supporting language by selecting for greater intelligence
what are frequency effects?
high frequency words read more quickly than low frequency words
what are regularity effects?
regular words read more quickly than irregular words
what are frequency-regularity interactions?
refer to how the frequency of a word (how often it appears in usage) interacts with its regularity (how predictable its form is based on linguistic rules)
what are the key aspects of frequency-regularity interactions?
- regular words (e.g., “jumped,” “talked”) follow predictable patterns (e.g., standard past tense formation)
- irregular words (e.g., “went,” “bought”) do not follow typical rules and must be memorized
- high-frequency words (both regular and irregular) are processed more quickly because they are encountered often
- low-frequency irregular words are the hardest to process since they require memorization but appear less often
what are 3 aquired neuropsychological disorders in reading?
surface dyslexia
phonological dyslexia
deep dyslexia
what is surface dyslexia?
difficulty in reading irregular words but fine with nonwords and regular words
what is phonological dyslexia?
difficulty in reading non-words but fine at regular and irregular words (double dissociation between irregular words and nonwords)
what is deep dyslexia?
difficulty with nonwords, irregular words and regular words but better with high imageable than low imageable words
often make semantic errors
what is orthographic knowledge?
visual knowledge of letters and words
what is phonological knowledge?
knowledge of how letters and words sound
what is semantic knowledge?
meaning of words
what is lexical knowledge?
word level knowledge (lexical-orthographic/phonological/semantic)
what is sub-lexical information?
sub-word information e.g individual letters or phonemes, groups of letters (graphemes) or groups of phonemes (syllables)
what is the dual route model?
this model suggests two pathways for word recognition:
1. lexical route: direct retrieval of whole-word representations (useful for high-frequency irregular words).
2. sublexical route: applying phonological rules to decode new or regular words (useful for low-frequency regular words)
what is route A of the dual route model?
sub-lexical route
what is route B of dual route model?
lexical-phonological route
what is route C of the dual route model?
lexical-semantic route
from print (letters) to pronounciation (phonemes) what forms a serial connection?
print-to-sound translation rules from the sub-lexical route
parallel connections of print (letters) to pronunciation (phonemes)
orthographic lexicon to route B to phonological lexicon
orthographic to semantic system to route C to phonological lexicon
basic idea of dual route model
- regular words can be read by all three routes
- irregular words can only be read by the lexicalroutes (both of them)
- nonwords can only be read by sub-lexical
grapheme-phoneme route - naming speed and pronunciation is based on the route that finishes first
what route is damanged in surface dyslexia?
damage to both lexical
routes, with sub-lexical route spared
what route is damaged in phonological dyselxia?
selective difficulty
in using sub-lexical route
what route is damaged in deep dyslexia?
patients can only read by the lexical-semantic route (and semantic route partly damaged)
horse race account of frequency and regularity effects
- high frequency words processed more quickly than low frequency words (within the lexical routes)
- regularity effects are due to the conflicting
pronunciations of irregular words derived from lexical and sub-lexical routes - conflict is avoided for high-frequency words, as lexical route finished before sub-lexical route- producing interaction
what is the impact of word length and landing position effects during reading? (joseph et al 2009)
short words appear to be identified more quickly than long words all else being equal
results showed that word length influenced children’s reading times and fixation positions on words
children exhibited stronger word length effects than adults in gaze durations and refixations
what is the impact of visual similarity on identifying words?
- TABLE/CABLE (neighbours)
- CROWN/CROW
(supersets/subsets) - TRIAL/TRAIL (transposed letters) are all similar to one another
some evidence of interference following an initial training phase, and clear evidence of interference the following day (bowers 2005) as there is competition in orthographic lexicon
what is the impact of age-of-acquisition (AoA) on reading times?
early acquired words read more quickly than late
studies show that people classify early-acquired words as real words more quickly than later-acquired ones
how do psychologists explain developmental dyslexia?
difficulty in learning to read despite normal intelligence and
opportunity to learn to read.
most cases developmental dyslexia is due to a mild difficulty
in phonological processing
what is the alternative approach to the dual route model?
parallel distributed processing approach
what is the parallel distributed processing approach?
- gets rid of lexical phonological route
- phonological and semantic routes work similarly
- introduces learning
what is linguistic determinism?
the claim that speakers of different languages are constrained to think and perceive in certain ways because of their specific language
orwell and linguistic determinism
if your language has no term for blue, you can’t see blue, if no term for “justice”, no corresponding concept
this is the idea behind “newspeak”
what is linguistic relativity?
the claim that different languages shape or bias (rather than determine) the thoughts of its
speakers
e.g., easier to perceive the difference between two colours if your
language distinguishes between them.
effect of linguistic relativity
language does not
fundamentally restrict our perceptual abilities, or
prevent us from entertaining any thoughts
rather, it biases thoughts (and in some cases improves them, to a limited degree).
what is thinking-for-speaking?
claim here is that different languages shape thoughts (perceptions) of speakers while speaking
this contrasts with linguistic relativity research which
generally focuses on the impact of language on nonlinguistic thinking.
“the elephant ate the peanuts”
– in english, must include tense – that the event happened in
the past
– in mandarin and indonesian, tense is optional, and not
marked on the verb
– in russian, the verb includes tense and also whether the peanut-eater was male of female (but only in past tense),
and whether the peanut-eater ate all the peanuts.
– in turkish, must specify whether the eating of the peanuts
was witnessed or if it was hearsay
time and linguistic relativity
in english, we generally use front/back terms to talk about time
– good times ahead, hardships behind.
in mandarin, vertical metaphors are common
– earlier events are “shang” (up), later events are xia
(down)
space and linguistic relativity
- relative terms specify directions and locations relative
to the viewer (english, dutch, japanese)
– e.g., Left/right, front/back - intrinsic terms specify locations in term of objectcentred coordinates (arrente, australia)
– e.g., “the ball is at the foot of the hill” - absolute terms specify locations based on a global reference frame centred on the object (totonac,
mexico). - e.g., “the ball is north of the hill”
objects and linguistic relativity
many languages include grammatical gender
– spanish, french, italian mark objects as being masculine or feminine
– E.g., toasters are masculine in some languages, feminine in others.
no grammatical gender in English
why colour and speech sounds?
because our perceptions of colour and sounds demonstrate categorical perception (CP). CP is revealed
when we perceive discrete categories in the world when
in fact the world is continuous.
two features of categorical pereception:
- sharp labelling (identification) function
- discontinuous discrimination
colour and categorical perception
- colour is a classic case of “categorical perception”: when our perceptions categorize stimuli in an arbitrary manner given the nature of the physical world
- our colour perceptions do not faithfully mirror the physical properties of light. perceived
differences among wavelengths that fall into different categories are exaggerated, and
differences among wavelengths that fall within same category are minimized
phoneme perception and categorical perception
although stimuli that vary on voice onset time vary in a continuous way, our
perceptions are categorical – either “ba”
or “pa”
why do we show catergorical perectpion in the domain of vision and speech?
- the language(s) we speak impact on our perception of colour and speech sounds
- the physiology of the
visual and auditory systems is such that we would show categorical perception independent of
language
categorical perception- the language(s) we speak impact on our perception of colour and speech sounds
- e.g., since english distinguishes between blue and green at a
given wavelength, we reorganize colour space to make this
contrast salient
– e.g., if p/b, or l/r contrasts are critical for our language, we
reorganize our perception to improve perception of these
sounds
categorical perception- the physiology of the
visual and auditory systems is such that we would show categorical perception independent of
language
– the colour terms we use are a by-product of what colours appear the most salient (independent of language)
– the phonemes selected for language are the by-product of the acoustic contrasts are most salient based on auditory physiology
animals and categorical perception
- chinchillas first trained to identify a /d/ (0 VOT) and /t/ (+80
VOT) stimulus spoken by humans - then they were presented with
ambiguous (synthetic) sounds that
varied in their VOT from 0 to 80 - task was to identify (label) the stimuli
- humans given a similar task
- the form of the labeling functions and the “phonetic boundaries” for chinchillas and english-speaking adults were similar
kuhl et al (2006)
in the task above, children hear a sequence of /ra/ trials, and occasionally a /la/
trial occurs (and vice versa), and trained to turn their head on change trials
at about 6-8 months, babies are better at discriminating
phonemes in all languages, but perception changes with more exposure to their native language, so that it becomes
more difficult to distinguish phonemes from other languages
brown and lenneberg (1954)- is the perception of colour biased by language?
- participants shown four target chips, that were either high
or low codeable - after short delay, asked to select matches from an array of colour chips (240 chips)
- participants better able to remember a colour that had a high codability colour name.
- this taken to support the claim that language
impacts on colour perception and memory
issues with brown and lennenberg (1954)
codability effects might be due to the physiology of the
colour system
the REASON why we have the colour
terms RED, BLUE, etc. is because these colours are more salient (e.g., due to rods and cones in fovea)
this in turn makes our memory better for these colours
roberson, davies and davidoff (2000)
berinmo tribe
new guinea
labels colours
quite differently
than english
different languages carve up colour
space differently with terms
roberson, davies and davidoff (2000)- LTM for colour and paired associate learning task
-12 monolingual berimno speakers took part.
- 8 focal and 8 non-focal ENGLISH colours paired with
pictures of familiar nuts
- 8 pictures of nuts randomly presented on table, and colour
chips placed on top then pictures removed, shuffled, and participants asked to place colour chips back on pictures.
performed 5x a day for 5 days (or until correct)
roberson, davies and davidoff (2000) results
berinmo participants did not remember
english focal colours better
rather, they remembered berinmo focal colours better
gilbert et al (2006)- whorf hypothesis is supported in the right visual field but not the left
- nature of this neural organization predicts that, if language affects perception, it should do so more in the right visual field than in the left visual field, an idea unexamined in the debate
- here, we find support for this proposal in lateralized color discrimination tasks
- reaction times to targets in the right visual field were faster when the target and distractor colors had different names; in contrast, reaction times to targets in the left visual field were not affected by the names of the target and distractor colors
- this pattern was disrupted when participants performed a secondary task that engaged verbal working memory but not a task making comparable demands on spatial working memory
- it appears that people view the right (but not the left) half of their visual world through the lens of their native language
