Cognitive Psychology
Introduction
“The branch of psychology devoted to the scientific study of the mind” (Braisby & Gellatly,
2012:2)
“… aiming to understand human cognition by observing the behaviour of people
performing various cognitive tasks” (Eysenck & Keane, 2015:1)
•
-Inferring how the mind works through observing behaviour (indirect)
The 19th and 20th Centuries
William James (1842-1910)
•
- Functionalist psychology is understanding mental processes rather than structure;
‘what’ and ‘why’
•
- Structuralism: take something apart and study its components
•
- Functionalism: study the function of something and what is produces
Hermann Ebbinghaus (1850-1909)
• Influenced by associationism; how events or ideas are associated together to constitute
learning
• He took the meaning out of the stimuli in order to isolate precise mechanisms
Behaviourism; no reference to mental processes
•
- Gestalt Psychology; psychological phenomena is best understood when viewed as
‘wholes’ rather than parts
Sir Frederick Bartlett (1886-1969)
•
- Focused on ‘real-life’ remembering and thinking and incorporating context and
meaning
•
- Schemata
Jerome Bruner (1915-2016)
•
-Employing the experimental method
•
-Demonstrated that the behaviourist approach was inadequate in explaining
behaviour and that the assumption of underlying cognitive processes was necessary
•
-Leader of the ‘first cognitive revolution’ alongside Lashley and Chomsky
Theories, Models and Constructs
• Cognitive theory requires the assumption of unobservable ‘theoretical constructs’
• A model connects the unobservable constructs with observable and measurable
behaviour so cognitive psychologists create models that connect mental structures
and/or processes to behaviour
• These models can also generate further prediction about behaviour that can be
empirically tested
• A model is not the thing it models, it’s a representation of it
Experimental Cognitive Psychology Issues
•
-Ecological validity
•
-The indirect nature of the evidence
•
-Theories are often expressed verbally. Therefore, they can be vague.
•
-No BIG PICTURE.
•
-No single theory of how the mind works in its entirety.
•
-Few attempts at Cognitive Architectures such as ACT-R (Anderson et al., 2004)
Parallel Processing: there is now evidence that multiple processes can operate
simultaneously
Salthouse (1984): Skilled typists
•
-Input (encoding the material)
•
-Parsing (breaking down words into characters)
•
-Translation (characters to finger movements)
•
-Execution stage (triggering of keystrokes)
•
-BUT: Several stages occur simultaneously.
Introspection
•
-Miller (1962:56): “It is the result of thinking, not the process of thinking,
that appears spontaneously in consciousness”
•
-Ericsson and Simon argue it can be useful if certain criteria are adhered to;
• Best to obtain reports during a test due to fallible memory
• Participants should not be asked about their general interpretation of a situation, needs
to be specific.
• The usefulness of introspection is limited (people cannot comment on their neuronal
processes)
Behavioural Methods
Cognitive Neuroscience
A relatively recent development due to technological advances (continuous & rapid).
Studying the brain in conjunction to behaviour.
Very useful for constraining and informing Cognitive Theory
• Single-Unit Recording - Electrodes on skull or in, after surgery.
• Event-related Potentials (Based on EEG)
• Positron Emission Tomography
• Functional Magnetic Resonance Imaging
• Magneto-encephalography
• Transcranial Magnetic Stimulation
EEG - Electroencephalography
Neurones exhibit chemical and electrical activity. EEG detects neuronal electrical current
conducted through the skull. Consequently, EEG is not ideal for identifying the source of
the activity (spatial resolution) However, it is excellent for identifying the timing of the
activity (time resolution).
• Detection of brain death
• Sleep research
• Measurement of drug effects (Anesthesia)
Event-related potentials
EEG data can be separated into ‘epochs’ .. time lacked to stimulus presentation. ERPs are
extracted by averaging the epochs. Therefore, ERPs can be compared across different
experimental conditions.
MEG - Magnetoencephalography
Neurones exhibit chemical AND electrical activity. The electrical activity also produces
magnetic fields. MEG detects magnetic fields generated by neutrons firing simultaneously.
MEG does so with SQUIDS
MEG is better than EEG for identifying the source of the activity (spatial resolution) but still
not great. It is also better for time resolution.
SQUID
Superconducting Quantum Interference Device. MEG machines are expensive to acquire
and costly to run because of replacing helium, and need for engineers. Very specialist
conditions needed as they're very very sensitive. Therefore, EEG comparatively is very
cheap.
fMRI
• Similar to PET (Positron Emission Tomography) in logic. But is non invasive and less
expensive
• fMRI reflects brain activity though changes in blood flow (magnetic scanner)
• Excellent spatial resolution
• Only takes up to 3 secs, though not very good time resolution
• It identifies areas that correlate with processes. It is not clear whether they’re essential
for the function.
Transcranial magnetic stimulation (TMS) is a form of neurostimulation. TMS is a noninvasive procedure in which a changing magnetic field is used to cause electric current to
flow in a small targeted region of the brain via electromagnetic induction.
TMS is used diagnostically to measure the connection between the central nervous system
and skeletal muscle to evaluate damage in a wide variety of disease states, including
stroke, multiple sclerosis, amyotrophic lateral sclerosis, movement disorders, and motor
neuron diseases
Cognitive Neuroscience
Issues:
• It happens somewhere ‘north of the neck’ (Fodor, 1999)
• The last thing we need is a return of phrenology (shape and size of cranium to indicate
intelligence)
• Correlational (not TMS)
• Functional specialisation is unlikely for higher order processes - likely to involve networks
• False positives or ‘abuse of statistics’
Neuropsychology
Is the study of brain-damaged patients.
HM (Henry Molaison, 1926-2008) was arguably the most famous case. Severe anterograde
amnesia after brain surgery. - cant create new memories after the amnesia.
Highlighted the importance of the Hippocampus for normal memory function.
Assumptions:
1. Functional modularity
2. Anatomical modularity
3. Uniformity of functional architecture
4. Subtractivity
Lesion studies
Problems;
• We have no control over the lesions
• We do not have the opportunity to examine the patients pre-impairment performance
• Too few patients with variable lesions
• Post-Post-Injury synaptic modification? Strategic adaption?
Issues:
• Dependant on too many assumptions
• Compensatory studies
• Extent of damage/lesion (how many modules? same across patients?)
Perception
“the analysis of sensory information” (Pike, Edgar & Edgar, 2012)
- sensation is stupid.. it only involves the detection of forms of energy in our environment.
This is vague and therefore ‘correct’
The Gestalt Approach
One of the earliest attempts at describing perceptual organisation, the overarching law of
Pragnanz.
Critique
• Lack of realism in terms of ‘real world’ perception.
• More descriptive than explanatory
• Assumed processes are mostly bottom-up (and innate). HOWEVER, the role of top-down
processes has been demonstrated in figure-ground segregation (e.g. ‘LIFE’, see also
Grill-Spector & Kanwisher, 2005).
Direct/Ecological Perception
James Jerome Gibson (1904 - 80)
• The ‘raw’ retinal image is not the basis of perception (c.f. Marr) but the multitude of cues
present in the environment.
•
No higher cognitive processing is required (no top-down element).
•
We perceive objects directly within the context of an environment.
•
Therefore: Experiments need to be ecologically valid! c.f. Gestalt approach
Critique
• Demonstrated value of ecological validity, and the (until then ignored) richness of
information available.
• The human visual system evolved according to our environment (Palmer, 1981)
• Vague about precise mechanisms
• Vague about precise mechanisms.
•
Marr (1982: 60): “… the detection of physical invariants, like image surfaces, is exactly
and precisely an information processing problem, in modern terminology. […] he
vastly underrated the sheer difficulty of such detection.”
• Fodor & Pylyshyn (1981: 189): “What you see when you see a thing depends upon what
the thing you see is. But what you see the thing as, depends upon what you know
about what you are seeing.”
•
E.g. Mr Smith and the Pole Star illustration!
Indirect/Constructive perception
The antithesis of ‘direct perception’. Also known as indirect perception.
Sensory data, knowledge stored in memory, cognitive inferences.
Main proponents;
• Richard Gregory (1923 -2010)
•
We formulate ‘perceptual hypotheses’. We accept the one that best fits our data.
Gregory (1980)
• Irvin Rock (1922-1995)
•
“Perception is based on prior perception, implying a perception-perception chain of
causality.” (Rock, 1997)
Marr’s (1982) Three levels of cognition
LEVEL 1: The computational level
What (input, output) & WHY - Function
LEVEL 2: The algorithmic/representation level
How - Process
LEVEL 3: The implementational level
The ‘hardware’ involved – The brain
Marr’s computational approach
Essentially, an information processing approach to vision.
Focus: Computational and algorithmic levels of description.
Most of his work involved computer models, and consequently the implementational level
was largely ignored (i.e. BRAIN!).
Four stages of the analysis of the retinal image:
• Grey level description - perceived intensities
•
colourless information based on light intensity as it reaches the retina
• Primal sketch - curves, lines, edges and boundaries
•
edge, contour and region of similarity detection (using Gaussian blurring)
• 2 ½ D sketch - orientation, depth, size, shape, and location information
•
all in relation to the observer
• 3D object-centred description
•
independent of the observers viewpoint (partially obscured objects are fully
represented)
•
this involves some top down processing, previous knowledge influences perception.
1-3 are viewpoint dependant or viewer centred. 4 is viewpoint-invariant object centred.
Critique
• Some computer models suggest Marr’s theory is plausible. HOWEVER, just because a
programme can accomplish the task, it does not mean human perception works the
same way.
• Neglected the implementational level.
• Some of the details of the theory have been demonstrated as wrong. However, the
approach was revolutionary and extremely influential.
• No way to accommodate Dorsal and Ventral pathways into his model
Two visual systems? - Milner & Goodale (1995, 1998)
Ventral Pathway: Vision for perception Identification of objects in our environment
Dorsal Pathway: Vision for action Location of objects in relation to ourselves
Perenin & Vighetto (1988): Damage in dorsal pathway associated with failure to
rotate hand appropriately in order to insert in slot of varying orientations.
James et al. (2003): Damage in ventral pathway associated with failure to recognize
objects while grasping behaviour remained normal (case of DF).
fMRI: DF did not show increased activation in ventral stream when presented with
line drawings of objects as opposed to random lines. Dorsal stream showed
increased activation for grasping.
Norman 2002
The Dorsal System picks up visual info to allow interaction with the environment (bottom-up).
• It does so (1) quickly, (2) without much involvement of conscious awareness (3) without requiring
cognitive effort for ‘interpretation’.
• Perception according to ecologists?
The Ventral System is dedicated to recognising objects and events (top-down).
• It is (1) slower, (2) involves more awareness (3) requires the use of previously stored information
for ‘interpretation’.
• Perception according to constructivists?
Attention
Eysenck & Keane (2015:155): “Attention typically refers to selectivity of processing”
i.e. this would include external AND internal environments.
William James (1890): “Attention is the taking possession by the mind, in clear and vivid
form, of one out of what seem several simultaneously possible objects OR trains of
thought”.
Active: Top-down (directed by goals, knowledge, and expectations)
Passive: Bottom-up (attracted by external stimuli)
Signal Detection (vigilance and search)
Focused/Selective Attention: Attending to one source of information and actively ignoring
all others.
The ‘Cocktail Party’ problem.
• Shadowing was achieved by attending to physical characteristics of the two voices (i.e.
harder if the two messages were in the same voice).
• When shadowing, ppts noticed physical changes in the unattended message (e.g. sex of
the speaker), but NOT semantic changes (e.g. change in language).
• … unless semantic changes are salient, such as your own name. One third of participants
noticed hearing their own name (Moray, 1959).
Broadbent’s (1958) Filter Model of Attention
• Input from multiple sensory channels reaches ‘attentional filter’ (Early Selection).
• The filter allows the further processing of only one channel on the basis of physical
characteristics (PLUS: stimuli with distinctive physical characteristics may also pass
through).
• Why? To prevent overloading of the attention mechanisms.
Broadbent (1958): When presented with 564 in one ear and 938 in the other
simultaneously, ppts were more likely to report “564938” (based on ear of input) rather
than “596348” (based on when numbers were presented).
Multi-tasking/Divided Attention: Performing two tasks at the same time.
Focused Auditory Attention
Treisman’s (1960, 1964) Attenuation Model
Similar to Broadbent’s model, but with an attenuator instead of a filter.
“The only difference between unattended and attended messages is that the unattended
message has its overall signal-to-noise ratio reduced by the selective filter, and therefore
fails to excite lexical entries for any of its content except a few words or phrases with
unusually low detection thresholds” (Treisman, 1986: 123).
• Some top-down processing accommodated for.
• Location of selective filter is flexible and dependent on processing capacity.
Deutsch & Deutsch’s (1963) Late Filter Model
The filter is placed after sensory analysis (like other models) BUT also after some
perceptual and semantic analysis (Late Selection).
So, all messages receive the same processing whether they are attended or not.
• HOWEVER: Coch, Sanders & Neville (2005) – EEG Study
• ERPs 100ms after target presentation were greater for the attended message than for the
unattended one.
• THEREFORE: Evidence that the attended message received more processing early on.
Evidence against Broadbent’s Model
Moray (1959): Participants often detected their own name when presented in the
unattended ear.
Von Wright, Anderson and Stenman (1975): GSR for synonyms of unattended words
(previously paired with electric shock)
Li et al. (2011): Women unhappy with their weight made more shadowing errors when
distractors in the unattended ear were weight-related (i.e. evidence of top-down
processing).
Which model? Treisman or D&D?
• Treisman & Riley (1969)
• Shadowing of attended message in one ear.
• Targets appeared in both ears and participants were told to tap whenever they heard the
target (irrespective of channel).
•
According to D&D, input channel should not matter.
•
According to Treisman, more targets should be detected in the attended channel.
• Results supported Treisman’s theory.
Theories based on shadowing and dichotic listening;
A critique:
• Difficult to control onset and offset of auditory stimuli (more so at the time).
• All theories not easily falsifiable due to vagueness.
• What about the roles of arousal, task difficulty, practice?
• Styles (1997: 28): “Finding out where selection takes place may not help to understand
why or how it happens”
• Leakage Vs Slippage – Dawson & Schell (1982): Physiological responses to the
unattended message occurred when attention may have ‘slipped’ to the unattended
message.
•
Broadbent may have not been so wrong after all!
Sensory Memory
Iconic and Echoic memory
• First coined as terms by Neisser (1967) along with the term Cognitive Psychology.
All sensory information persists for some time after the end of stimulation. This
persistence allows us to extract pertinent information for further analysis (i.e. The ‘Why’
functional issue).
The phenomenon has been known for MANY years.
One of the first experiments was conducted by Segner in 1740!
• Glowing coal attached to cartwheel.
• Adjusted the spin to create a full, uninterrupted circle. A complete circle was perceived
only if each rotation lasted no more than 100ms.
• His estimate of visual persistence (100ms) was similar to more modern estimates (e.g.
Haber & Nathanson, 1968).
Efron (1970)
• A light flash was the target stimulus.
• Participants had to adjust an indicator (such as an auditory click) either to the onset or to
the offset of the target.
• The offset was overestimated at least by 200ms.
• Interestingly the longer the duration of the stimulus, the shorter the overestimation.
That is, the longer the encoding, the faster the forgetting!
Iconic Memory
Averbach (1963)
• An array of black dots was shown through a t-scope.
• The number of dots and the exposure duration were manipulated.
• Participants had to estimate the number of dots presented.
• “Subitising” (i.e. identifying
Sperling (1960,1967)
Presented a metric of 12 letters for only 100 milliseconds.
Full report procedure
• When participants were asked to report as many letters as possible immediately, the
mean was 4.5 (out of 12-38%)
Partial report procedure
• High, low or medium tone sounded after end of matrix presentation. Each line was a
different tone.
• 3 out of 4 items (75%) of any line could be reported. Sperling reported that if 75 percent
for each line then you would remember 75 percent of it all.
• But if 75% should be recalled then why was only 38% in the full report procedure?
• Iconic memory is short and expires.
Echoic Memory
Evidence from Broadbent 1958 experiments on diabetic listening .
• When the task ended often participants could remember the last few words of the
unattended message.
Cowan et al. (1990)
• Participants read a novel with headphones on.
• Nine syllables through headphones at random intervals
• BEE BIB BEB DEE DID DEB GEE GIB GEB
• At light signal, participants were to report the last syllable heard (1s, 5s, or 10s before).
• Performance was good only at 1s delay.
• HOWEVER, when participants were instructed to monitor the syllables while reading,
the time interval did not matter!
Different stages in iconic memory storage?
Turvey (1973)
Masking: Remember change blindness (Rensink, 1997)?
Brightness masking:
• Amount of energy and duration.
• Only disruptive if presented on same eye as stimuli.
Pattern masking:
• Energy not important… instead, interval between presentation of stimuli and mask
onset.
• Not ‘eye-specific’!
CRITIQUE
• Haber (1983):
• Sensory memory experiments are ‘artificial’.
• Objects in the real visual world ‘stick around’ anyway!
• What’s the point? Unless one is trying to read by night in a thunderstorm and counting
on lightning!
• Coltheart’s (1983) response: Ensures that the perceptual system has enough time to
process stimuli.
• Neath & Surprenant (2005): Sensory memory does not exist! Stimulus persistence (of
sensory nature) vs Information Persistence (STM).
• Memory does not work this way (see Efron, 1970).
Working Memory
Short term memory
In the late 1800s William James distinguished between primary and secondary memory
• The main number 7: Miller concluded that out information processing ranges from 5 to 9
items, so 7 plus or minus 2.
• Double dissociation: immediate memory recall is worse when the items are phonetically
similar (eg. Car, cat, hat and ham) However, the inverse is true for longer retention
intervals
The serial portion curve
When the subjects are instructed to free recall a list of items;
Primacy effect: they tend to remember best the items in the beginning of the list
Regency effect: they tend to remember best the items near the end of the list
The longer the wait for the free recall the fewer items recalled from the end of the list.
So the recency effect appears to be based on STM. Evidence against a unitary view of
memory.
Baddeley and Warrington 1970 employed free recall and the serial position curve to
compare the performances of healthy subjects and amnesic patients.
• Amnesic's performed normally on the widget span task STM, and showed a normal
regency affect at free recall STM component. However, their free really of early items
was impaired compared to controls.
Some core model assumptions:
• Information is transferred to and from LTM through STM only.
• The longer an item is held in STM, the greater the probability it’ll be transferred to LTM.
• STM is unitary.
Shallice and Warrington 1970:
KF sustained a severe head injury and resulted in a left hemisphere lesion next to the
sylvian fissure.
According to several tests, KF cognitive functions were near to normal but his midget span
was very low (1-2 items rather than 7)
KF’s auditory STM performance was impaired with all types of materials (digits, words and
even worse with letter strings)
Strong evidence for the STM LTM distinction:
• Amnesic patients like HM have intact STM and impaired LTM
•
Single dissociation
•
Alternatively: STM tasks are easier than LTM tasks.
• However, KFs case provides a double dissociation.
ON the other hand KF provides evidence against the Atkinson and Shiffrin model:
• His LTM was unimpaired (info was assumed to go into LTM only via STM)
• Other cognitive functions assumed to rely on working STM were also intact.
Baddeley and Hitch 1974
Dual task experiments have been the most illuminating.
If working memory is involved in reasoning, language comprehension and similar cognitive
tasks, such tasks should be disrupted by irrelevant STM loads.
• Indeed but the disruption was not ‘catastrophic’ suggesting different components
• Similarly, phonetic similarity (shown to disrupt STM) disrupted reasoning and
comprehension, but again not severely
• Findings consistent with KFs condition.
A multi-component model of working memory.
Phonetical Loop Components
Phonological store: keeps speech-based information for 1-2 seconds.
Subvocalisation: 1) translates visual information into speech based information and
transfers it to the phonological store. 2) refreshes information already in the phonological
store prevents it from decaying.
Baddeley et al. 1975
• Participants saw lists of 10 words. Each comprised of words with one, two, three, four or
five syllables.
• Recall fell as the length of the words increased
• Also, reading rate was related to amount of recall (the faster the reader, the higher the
recall)
Articulatory suppression (eg. The the the the )
• Eliminates the word length effect and the similarity effect by occupying the
subvocalisation process.
Evidence for a subvocalisation process of rehearsing verbal material to prevent their decay
from the phonological store.
Irrelevant speech effect: recalling visually presented consonants is more difficult if
irrelevant speech is played in the background
• That is because speech has a direct access to the phonological loop.
So: non speech items should not have the same effect
• Indeed they don’t
• Additionally, articulatory suppression disrupts the irrelevant speech effect
• however, if the irrelevant non-speech sounds vary over time they are disruptive.
Visuospatial sketchpad
Subjects used the method of loci OR simple rote rehearsal to memorise words
Half of the subjects from each task had to do a concurrent tracking tasking (track a moving
sound) which is a spatial task (non-visual)
The tracking task disrupted memory performance when the method of loci was used, but
not when rote rehearsal was used.
• A visual non spatial talk of detecting brightness changes had no disruptive effect
Double dislocation between the visual and the spatial aspects of the visuo-spatial sketch
pad with neurophysiological evidence :
• Patients have shown isolated impairment with spatial tasks but not visual tasks while
other patients have shown the inverse pattern
The central executive
“The most important but least understood component of working memory” (Baddeley, 2003:835)
Homunculus?
Baddeley: a system for attentional control:
Focusing, diving, switching attention
A common task is random generation.
This model was refined and the episodic buffer was added largely to solve the binding problem
A limited capacity to store supporting the CE and storing info from the other slave systems and
LTM in bound form.
Cowens embedded process model:
LTM is partitioned in three ways: The larger portion with low activation. A subset currently
activated because of specific cognitive activity and perceptual input The focus of attention and
awareness. One of many alternative models.
Conclusion;
The WM model has withstood well the test of time.
Alternative models have never been as popular.
However, it has been criticised on several grounds and most importantly on its focus on systems
rather than processes.
Research (even after all these years) is ongoing and revealing new insight every year.
Language and Thought
Differences between languages
Human Language is characterised by certain universal elements (symbolic nature etc)
Different phonemes, different lexicons and different synoptical structures.
Examples;
Burling (1970) a Burmese oral language Garo has several words for:
Basket - on head, shoulders, hands, with a strap
Rice - cooked and uncooked
The English language has 11 basic colour terms while Garo has 4. Such linguistic differences
may reflect obvious cultural differences.
Chomsky 1975 - Langauge reflects cognition.
Language affects thought
The constructive nature of memory
Carmichael, Hogan and Walter (1932). Participants shown simple drawing and told that
they liked like a particular thing, and asked to re draw it from memory.
Flexibility in out memory function can lead to errors.
e.g. Loftus and Palmer (1974) Students watched a film that included a car accident…
Linguistic Relativity
The Sapir-Whorf Hypothesis:
Speakers of different languages have different cognitive systems. As a result they view the
world differently. Language AFFECTS thought.
Linguistic relativism as expressed by Whorf should be distinguished from linguistic
determinism which is an extreme version of it.
Language determines thoughts, we are incapable of thoughts that we cant express vocally.
Linguistic determinism has been largely discredited & Linguistic realism is still debated.
Against Determinism
What about the feeling of not being able to express our thoughts? Unlike thoughts
language is vague, sketchy and limited.
Animals incapable of language still have cognitive abilities, it is not effective enough to
determine thought.
Bloom (1981)
Chinese has no subjunctives “if it were to rain, I would take my umbrella”
Bloom created Eng and Chinese versions of stories that included such counterfactual
elements. Chinese could not understand the stories.
It turns out these were just badly translated (Au, 1983)
Winawer et al. (2007)
Colour perception - in Russian there is a distinction between light and dark blue,
representing different categories.
Note: doesn’t require language.
Levinson (1996)
Dutch: heavy reliance on spatial terms.
Tzeltal: Exclusive reliance on absolute or fixed spatial terms (North/South)
Participants sat at a table with an arrow in front of them, then they were rotated 180
degrees and asked to point to another arrow the same as they had just seen.
Dutch made reactive judgements, and Tzeltals chose in spatial terms.
Hoffman, Lau and Johnson (1986)
Tested English-Chinese bilinguals. US
Tested the ‘drift toward stereotypes’ effect (memory showing distortion of details based on
activated stereotype)
Two mutually exclusive stereotypes;
English - artistic temperament stereotype (brilliant, impulsive and unreliable)
Chinese - “Shi Gu” stereotype (worldly, experienced, socially skillful, devoted and reserved)
Different measures all suggested the drift towards stereotypes was only present when the
language corresponded to the language-specific stereotype.
Language Part 2
Reading; Eysenck & Keane (2015) Chapter 9
Reading and speech perception are similar:
– You understand the meaning of this sentence in the same way regardless of whether
you read it or heard it.
HOWEVER:
– Speech is spread in time and transitory
– In speech, there are no clear gaps between words
– But speech provides prosodic cues
– Also, speech can be accompanied by gestures
Relationship between orthography and phonology. Caravolas at al. 2013
Think about “Although”
Children’s early phonemic skills predict their furture reading skills (Melby-Lervag et al, 2012)
Van Orden 1987
– Used homophones (Rows – Rose)
– Participants made more errors when asked: Is it a flower? Rows then Robs
This finding demonstrates the importance of phonology in reading.
Rastle and Brysbaert (2006) meta-analysis:
– When words are preceded by non-word homophones (e.g. klip preceding the word
clip), they are processed more quickly, even if the non-word is masked and not
consciously perceived.
– Such evidence supports the ‘strong phonological model’ which argues that
phonology is crucial for reading.
HOWEVER: YGA, a patient with impaired phonological processing, had no trouble
understanding the meaning of visually presented words (Han and Bi, 2009).
McClelland & Rumelhart (1981): Interactive Activation Model
Three Levels
- Detection of a feature
leads to excitation of
relevant letters and
inhibition of all others.
- When a letter is
identified, words
containing that letter in
that position are
excited and all others
are inhibited.
- An excited letter will
also further excite and
inhibit relevant
features.
- An activated word will
also excite and inhibit
relevant letters.
Top down and bottom up
processing working together.
Processing in auditory speech perception –
cutler and Clifton 1999
Speech perception SHOULD be hard.
Speech rate: Around 10 phonemes per
second.
We can understand speech even at 50-60
phonemes per second! (Werker & Tees,
1992)
The segmentation problem – How do we
know when a word ends, and another
begins?
Co-articulation – The sound of a phoneme
varies depending on what phonemes
surround it (SPOT-POT).
Individual differences between speakers.
Degraded speech.
The McGurk Effect
Auditory speech perception is often assisted by lip-reading.
BUT: top-down processes also play a role – effect of sentence content. (Windmann, 2004)
Categorical perception of phonemes
Phonemes in any language appear to being to discrete categories.
– Although the /p/ sounds slightly different in SPOT and POT but it is still perceived as
/p/ in both.
Raizada and Poldrack -2007: Ppts listened to and paired stimuli along the continuum
between /ba/ and /da/
The influence of context (top-down)
Lexical identification drift:
– Ganong (1980): Ppts are presented with sounds ranging from a word (e.g. ‘dish’) to a
non-word (e.g. ‘tish’). Ambiguous (i.e. in-between) phonemes were more likely to be
heard as phonemes that produced a real word.
Phonemic restoration effect:
– Warren & Warren (1970): Ppts heard degraded sentences. E.g.
o The *eel was on the axle.
o The *eel was on the shoe. Etc
– Ppts were more likely to hear ‘wheel’ in the first case and ‘heel’ in the second.
Speech perception as ordinary
The TRACE model
– Connections between levels are excitatory while connections within levels are
inhibitory.
– Different activation levels and strengths of interconnections.
– Excitations and inhibitions lead to a pattern of activation or ‘trace’.
Consistent with top-down effects such as the lexical identification shift.
Mirman et al. (2008): Detect a specific phoneme in words and non-words. Words were
presented on 80% or 20% of the trials. See next slide for results.
McClelland and Rumelhart (1986) produced successful computer simulations in support of
TRACE.
Speech perception as special
Speech is perceived through specialized processes.
Motor theory of speech perception (Liberman et al., 1967; Liberman & Mattingly, 1985 – for
update):
– There is a specialised speech perception ‘module’.
– The module is innate.
– The module processes information from intended speech ‘gestures’.
– Phonetic perception is a ‘motor event’. The acoustic patterns that are received are
information about the underlying gestures.
Motor theory of speech perception (Liberman et al., 1967; Liberman & Mattingly, 1985 –
for update):
Some evidence:
– Dorman et al. (1979): A rather clever experiment…
– Participants heard a tape saying “Please say shop”.
– A 50ms gap was inserted artificially between ‘say’ and ‘shop’. As a result, ppts heard
‘chop’ instead of ‘shop’.
– WHY?
– If a person actually said “say chop”, they would HAVE to pause between the words
on the basis of our physiology.
The processing approach to memory
Memory as a series of processes operating at three interconnected stages;
 Encoding, Storage and Retrieval (Melton, 1963)
 The emphasis is drawn away from memory systems and stores, and places on the
processes in operation.
Encoding process – this is where Levels of Processing LOP comes in (Craik & Lockhart, 1972)
This article changed the focus from memory stores to memory processes.
It was cited in other journal articles 2700 times between its publication and 2002 – when a
special 30th anniversary edition of Memory came out.