Face recognition performance of individuals with Asperger syndrome on the Cambridge face memory test.
Darren Hedley, Neil Brewer, Robyn Young
Article first published online: 24 AUG 2011
DOI: 10.1002/aur.214 http://onlinelibrary.wiley.com/doi/10.1002/aur.214/abstract
This article is still in press, but was published online last month. This study had 34 subjects with Asperger syndrome and 42 nonautistic controls. It appears that while around a quarter of the study subjects with Asperger syndrome in this study have prosopagnosia (as defined by a test score from 2 to 3 SD’s below normal or mean), Asperger syndrome (a type of autism) is also not inconsistent with superior performance on the Cambridge Face Memory Test (CFMT), which is the best test of face recognition that I know of. Some features of the study that perhaps distinguish it from other studies of face recognition in autism are the use of a reliable and valid test of face recognition (Duchaine & Nakayama 2006), the study of face recognition in adults, not children, which is really important because face learning ability appears to be a skill that peaks at a surprisingly late stage in the life-span, into the third decade (Germine, Duchaine & Nakayama 2011), and if autistic people have a delay in development that could potentially affect or bias the results of studies of children and youths.
I was particularly interested in looking at the data for individual study subjects, but for some reason, in journal papers this seems to always be included in a miniature table that is either unreadable or unprintable, or both, or is absent altogether. Persevering, I was interested to find that none of the non-autistic study participants got a score in the prosopagnosia range, while eight out of 34 of the Asperger participants did, so there seems to be a definite association between having prosopagnosia and having a diagnosis of Asperger syndrome (AS). But at the other end of the spectrum of ability, the top score of the whole study, which I think must have been close to the super-recognizer range at 1.75, was achieved by a participant with AS, and there were two other with AS who got great scores. It appears that a fair proportion of those with AS got close to average scores. To the naked eye, it appears that there is a greater variation in face recognition ability in those with AS than in the normal adults tested. Why? Should we just accept this as a brute fact about AS, or should we look for special explanations for the top or bottom achievers in the AS group?
Is there something special about the top performers in the AS group? Given that there appears to be a link between autism and synaesthesia, and synaesthesia appears to be sometimes associated with savant-like superior ability in specific sensory or cognitive tasks (Banissy et al 2011) (Banissy, Walsh & Ward 2009) (Baron-Cohen et al 2007) (Simner, Mayo & Spiller 2009), and the association between savantism and autism is generally accepted, should we then ask if the three top-performing participants with AS might be synaesthetes who also have AS? If these connections are found in reality, should we then include superior face recognition (“super-recognizers”) among the many varied areas of mental performance that are regarded as savant skills and abilities? I have already discovered in a 2010 study of face recognition in the broader autism phenotype (BAP) one CFMT score from a father of an autistic child that appears to be close to a super-recognizer level of performance (Wilson et al 2010), as defined as two or more SD’s above the mean. I would have thought that this isn’t what researchers would expect to find in studies of autism or the BAP which use study participants who aren’t selected for any particular level of face recognition ability.
I’ve got to wonder whether people (children?) whose main social disability is prosopagnosia have been clumsily lumped into the category of autism. It appears that over three-quarters of the autistic subjects did not have a “severe face recognition impairment”, so we certainly can’t say that a severe impairment is typical of the group of people who have Asperger syndrome (AS) in this study, and my reading of the “enhanced perceptual functioning model” of autism seems to suggest that autistic people should have an advantage at visual tasks (Samson et al 2011). We know that prosopagnosia is a fairly common but not well recognized disability, and that the diagnosis rates for things like AS and autism have been climbing steadily for a long time. The question of why this has happened is one that has provoked huge controversy – is there a genuine increase in autism rates, or are more and more people being placed into the category, due to lower thresholds of “severity” required for a diagnosis, or the category of autism indiscriminately devouring other categories of people, such as the intellectually disabled and other uncommon or rare disabilities?
The possibility that prosopagnosics can be (incorrectly?) identified as cases of autism was demonstrated in a story about prosopagnosia from the Australian science television series Catalyst which was broadcast in 2007 (see link below). An anecdote about two children in a family which was later found to have members with developmental prosopagnosia, who had previously been diagnosed with autism, was recounted by a prosopagnosia researcher from Macquarie University and dramatized on the show. I should point out that neither of the face perception tests shown in this story are the CFMT. One face recognition test shown in the Catalyst story uses the faces of famous people and it relies upon the person being tested already knowing about the famous person and being able to give a name for the famous face, two tasks which are not face recognition, so as a test of face recognition it is far from pure and perfect.
Banissy, Michael J., Garrido, Lucia, Kusnir, Flor, Duchaine, Bradley, Walsh, Vincent and Ward, Jamie Superior Facial Expression, But Not Identity Recognition, in Mirror-Touch Synesthesia. Journal of Neuroscience. February 2, 2011, 31(5):1820-1824. doi:10.1523/JNEUROSCI.5759-09.2011 http://www.faceblind.org/social_perception/papers/Banissy11JN.pdf http://www.jneurosci.org/cgi/content/abstract/31/5/1820
Banissy, Michael J., Walsh, Vincent & Ward, Jamie Enhanced sensory perception in synaesthesia. Experimental Brain Research. 2009 Jul;196(4):565-71. Epub 2009 Jun 17. http://www.springerlink.com/content/406581u3507un270/ http://www.ncbi.nlm.nih.gov/pubmed/19533108
Baron-Cohen S, Bor D, Billington J, Asher JE, Wheelwright S and Ashwin C. Savant memory in a man with colour form-number synaesthesia and Asperger syndrome. Journal of Consciousness Studies. volume 14, number 9-10, September-October 2007, p. 237-251. http://www.imprint.co.uk/jcs_14_9-10.html
Duchaine, Brad & Nakayama, Ken The Cambridge Face Memory Test: Results for neurologically intact individuals and an investigation of its validity using inverted face stimuli and prosopagnosic participants. Neuropsychologia 44 (2006) 576–585.
Face blindness. Catalyst. ABC. broadcast 19/07/2007 http://www.abc.net.au/catalyst/stories/s1982889.htm (This story showed face recognition testing at Macquarie University and includes a small sample of the tests which viewers can try)
Germine, Laura T., Duchaine, Bradley, Nakayama, Ken Where cognitive development and aging meet: Face learning ability peaks after age 30. Cognition, Volume 118, Issue 2, February 2011, Pages 201-210. http://www.sciencedirect.com/science/article/pii/S0010027710002611
Hedley, Darren, Brewer, Neil, Young, Robyn Face recognition performance of individuals with Asperger syndrome on the Cambridge face memory test. Autism Research. Article first published online: 24 AUG 2011 DOI: 10.1002/aur.214 http://onlinelibrary.wiley.com/doi/10.1002/aur.214/abstract
Samson, Fabienne, Mottron, Laurent, Soulieres, Isabelle & Zeffiro, Thomas A. Enhanced visual functioning in autism: an ALE meta-analysis. Human Brain Mapping. Article first published online: 4 APR 2011 DOI: 10.1002/hbm.21307 http://onlinelibrary.wiley.com/doi/10.1002/hbm.21307/abstract
Simner, Julia, Mayo, Neil, Spiller, Mary-Jane A foundation for savantism? Visuo-spatial synaesthetes present with cognitive benefits. Cortex. Volume 45, issue 10, November-December 2009, Pages 1246-1260.
Wilson CE, Freeman P, Brock J, Burton AM, Palermo R Facial Identity Recognition in the Broader Autism Phenotype. PLoS ONE 2010 5(9): e12876. doi:10.1371/journal.pone.0012876