perceptual processing in autism weak central coherence
TRANSCRIPT
Perceptual Processing in Autism
Weak Central CoherenceWeak Central Coherence
Autism
Triad of Impairments (Wing and Gould, 1979) Triad of Impairments (Wing and Gould, 1979) Socialisation, communication, and imagination. Socialisation, communication, and imagination.
Non-social features Non-social features -restricted area of interest/ preoccupation with -restricted area of interest/ preoccupation with parts of objects parts of objects -desire for sameness and routine -desire for sameness and routine -excellent rote memory -excellent rote memory -savant abilities -savant abilities -islets of ability -islets of ability
Weak Central Coherence (WCC) Frith (1989) proposed that all features of Frith (1989) proposed that all features of
autism could be explained by a single deficit in autism could be explained by a single deficit in processing informationprocessing information
WCC involves two parts: WCC involves two parts: PerceptualPerceptual- a preference to process - a preference to process information locally rather than globally information locally rather than globally ConceptualConceptual-a failure to process -a failure to process contextual meaning or use prior knowledgecontextual meaning or use prior knowledge
Block Design Test (Shah & Frith, 1993)
Individuals with autism Individuals with autism were significantly faster were significantly faster than matched controls than matched controls
Embedded Figures Test (Shah & Frith, 1983)
Individuals with Individuals with autism were autism were significantly faster at significantly faster at locating the hidden locating the hidden figure than matched figure than matched controls.controls.
Autistic savant artists
Snowling and Frith (1986)
Those with autism fail to use context when Those with autism fail to use context when processing ambiguous homographs.processing ambiguous homographs.
e.g. The actor took a e.g. The actor took a bow.bow.
* Failure to process context = poor * Failure to process context = poor performance in autismperformance in autism
Tager-Flusberg (1991)
-hat-hat
-cow-cow
-peach-peach
-doll-doll
-boat-boat
-pencil-pencil
-apple-apple
-car-car
-banana-banana
-pear-pear
-mug-mug
-cherry-cherry
Happe (1996)
First attempt to explore First attempt to explore low-level visual low-level visual integration in autismintegration in autism
Found individuals with Found individuals with autism were less autism were less susceptible to illusions susceptible to illusions than matched controls than matched controls
Limitations of Happe’s study
Methodological Methodological -Verbal responses may be susceptible to -Verbal responses may be susceptible to bias –Does not tell us degree of susceptibility bias –Does not tell us degree of susceptibility
Theoretical Theoretical -No independent measure of WCC included -No independent measure of WCC included to confirm perception of illusions requires same to confirm perception of illusions requires same underlying ability as other CC tasks. underlying ability as other CC tasks.
Research questions
Can Happe’s findings be replicated using a Can Happe’s findings be replicated using a more precise and better controlled measure more precise and better controlled measure of susceptibility?of susceptibility?
Do measures of WCC predict susceptibility Do measures of WCC predict susceptibility to illusions?to illusions?
Ropar and Mitchell (2001) Four size illusions and Four size illusions and
their controls were their controls were presented on a laptop presented on a laptop computer. computer.
Subjects were instructed Subjects were instructed to use buttons on the to use buttons on the keyboard to adjust parts keyboard to adjust parts of the illusion until they of the illusion until they looked the same.looked the same.
Visual spatial tasks used as measures of WCC
Subject Characteristics
GroupGroup MLDMLD AutisticAutistic Year 3Year 3 Year 6Year 6 AspergerAsperger
nn 2020 1919 1919 1818 1111
CACA
meanmean
rangerange
12;1112;11
9;2-14;89;2-14;8
14;214;2
9;3-18;39;3-18;3
8;68;6
7;7-8;67;7-8;6
11;311;3
10;9-11;710;9-11;7
11;1011;10
8;4-15;48;4-15;4
VMAVMA
meanmean
rangerange
6;116;11
3;3-10;103;3-10;10
6;116;11
3;8-13;43;8-13;4
8;08;0
5;3-10;65;3-10;6
11;611;6
9;5-15;79;5-15;7
9;119;11
5;1-17;65;1-17;6
Titchener illusion
25
26
27
28
29
30
31
32
33
34
35
autistic asperger mld year 3 year 6
size
in
pix
els
illusion
control
Muller-Lyer illusion
0
20
40
60
80
100
120
autistic asperger mld year 3 year 6
siz
e in
pix
els
illusion
control
Ponzo illusion
51
5253
54
5556
57
5859
60
autistic asperger mld year 3 year 6
size
in p
ixel
s
illusion
control
Hat illusion
160
170
180
190
200
210
220
autistic asperger mld year 3 year 6
size
in p
ixel
s
illusion
control
Block Design Test
0
5
10
15
20
25
30
35
40
45
50
autistic asperger mld year 3 year 6
meanscore
Embedded Figures Test
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autistic asperger mld year 3 year 6
seco
nd
s
meantime
Rey Test
Mean scores for each group on copy and recall trials of the Rey Complex Figure Test
05
10152025303540
autistic asperger mld year 3 year 6
me
an
sco
re
copy
recall
Correlations between illusionsHatHat PonzoPonzo Muller-Muller-
LyerLyerTitchenerTitchener
XXXXXX rr=.23, =.23,
pp<.05<.05
rr=-.25,=-.25,
pp<.05<.05
rr=.01,=.01,
pp=.935=.935
HatHat
XXXXXX rr=-.13,=-.13,
pp=.262=.262
rr=-.11,=-.11,
pp=.352=.352
PonzoPonzo
XXXXXX rr=.03,=.03,
pp=.774=.774
Muller-Muller-LyerLyer
XXXXXX TitchenerTitchener
Correlations between visuo-spatial tasks *indicates significance with a Bonferroni correction of.005
EFTEFT BDTBDT Rey copyRey copy Rey recallRey recall
XXXXXX **rr=-.81, =-.81,
pp<.001<.001
**rr=-.68,=-.68,
pp<.001<.001
**rr=-.49,=-.49,
pp=.001=.001
EFTEFT
XXXXXX **rr=.72,=.72,
pp=.001=.001
**rr=.57,=.57,
pp=.001=.001
BDTBDT
XXXXXX **rr=.71,=.71,
pp=.001=.001
Rey copyRey copy
XXXXXX Rey recallRey recall
Correlations between visuo-spatial tasks and illusions
GroupGroup EFTEFT BDTBDT Rey copyRey copy Rey recallRey recall
AutisticAutistic -- -- Hat(.66)Hat(.66) --
AspergerAsperger -- -- -- --
MLDMLD Muller Muller (.55)(.55)
Muller Muller (-.50)(-.50)
-- --
Year 3Year 3 -- -- -- --
Year 6Year 6 Muller Muller (.74)(.74)
Muller Muller (-.73)(-.73)
Muller Muller (-.54)(-.54)
Muller Muller (-.62)(-.62)
Note: consistent with prediction / opposite to prediction
Summary of findings Can Happe’s findings be replicated using a more precise Can Happe’s findings be replicated using a more precise
and better controlled measure of susceptibility?and better controlled measure of susceptibility?
NoNo Do measures of WCC predict susceptibility to illusions?Do measures of WCC predict susceptibility to illusions?
Not in a way that supports HappeNot in a way that supports Happe.. Individuals with autism performed well in comparison Individuals with autism performed well in comparison
to control groups on visuo-spatial tasks.to control groups on visuo-spatial tasks.
Do individuals with autism perform well due to less capture by ”wholeness” or “meaning”?
Brian and Bryson (1996)
Superiority in visual search
O’Riordan et al (2001)
Narrowing of attentional spreadMann & Walker (2003)
Could explain Navon data
ssssssssss
ssssssssss
s s s s s s s
Boundary ExtensionIntraub (1990)
Boys with Asperger syndrome
Matched control boys
NN 18 18
Age (y;m) Mean 14;0 13;6
SD 2;0 1;7
Range 9;7-16;5 10;11-15;8
Verbal IQMean
101.9 97.6
SD 13.6 11.9
Range 73-123 73-115
Performance IQ Mean 99.4 105.6
SD 16.1 13.8
Range 66-133 75-124
Full scale IQ Mean 100.8 101.6
SD 14.5 12.7
Range 70-124 72-119
Chapman, Ropar, Mitchell & Ackroyd (2004)
Results
Clear boundary extension, with a mean value Clear boundary extension, with a mean value of 12.51% (i.e. as if 12.5% further away): , of 12.51% (i.e. as if 12.5% further away): , tt(35) = 10.78, (35) = 10.78, pp < .001, < .001, dd = 1.80. = 1.80.
The degree of boundary extension was The degree of boundary extension was virtually identical between those with and virtually identical between those with and without autismwithout autism
Summary
Contrary to prediction, boys with Contrary to prediction, boys with Asperger syndrome show at least as Asperger syndrome show at least as much boundary extension as much boundary extension as comparison participantscomparison participantsNarrowing of attentional spread?Narrowing of attentional spread?Sensitivity to the wider context?Sensitivity to the wider context?
Ropar and Mitchell (2002)
slanted
Perspective
slanted
Knowledge
not slanted
Ellipse
Stimulus Shape
Projected ShapeViewing Condition
Subject Characteristics
GroupGroup AutisticAutistic MLDMLD Age 9Age 9 Adults Adults
nn 2828 2020 1919 1414
CACA
meanmean
rangerange
13;613;6
(9;7-18;11)(9;7-18;11)
13;613;6
(11;0-15;6)(11;0-15;6)
9;49;4
(8;10-9;9)(8;10-9;9)
26;526;5
(15;10-48;7)(15;10-48;7)
VMAVMA
meanmean
rangerange
8;08;0
(2;9-15;7)(2;9-15;7)
8;58;5
(5;11-12;5)(5;11-12;5)
9;49;4
(8;10-9;9)(8;10-9;9)
--
Judgments of shape in each condition.
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adults age 9 mld autistic
num
ber i
n pi
xels
Ellipse
Perspective
Knowledge
Summary of findings Individuals with autism are less affected by Individuals with autism are less affected by
prior knowledge, but are equally affected by prior knowledge, but are equally affected by perspective cues.perspective cues.
Theoretical implications
Atypical visual processing in autism is Atypical visual processing in autism is better understood in terms of difficulties better understood in terms of difficulties with integrating conceptual information. with integrating conceptual information.
Evidence showing those with autism do utilise meaning Ropar and Mitchell, 2001Ropar and Mitchell, 2001 Pring and Hermelin, 1993Pring and Hermelin, 1993 Ameli et al., 1988Ameli et al., 1988
3 levels of coherence (Happe 1999) Perceptual Perceptual
-Little evidence-Little evidence Visuo-spatial constructionalVisuo-spatial constructional
- Fairly strong evidence - Fairly strong evidence
(but are these conceptual?)(but are these conceptual?) Verbal semantic (conceptual)Verbal semantic (conceptual)
-Mixed evidence-Mixed evidence