One of the main diagnostic criteria for Asperger Syndrome is a severe social impairment (American Psychiatric Association [DSM-IV-TR] 2000), something that has often been connected to a more specific impairment in facial recognition. However, the main diagnostic tool (the DSM-IV-TR) has received much criticism during later years and is soon to be revised (Woodbury-Smith & Volkmar 2009). Among other things, many researchers claim that the diagnosis should be complemented with a sliding scale of severity (Ring, Woodbury-Smith, Watson, Wheelright & Baron-Cohen 2008). The use of facial information is central in the social interaction of humans, evident in the special patterns of visual scanning that people employ for facial stimuli (Yarbus 1967). Because of that, this symptom of Asperger Syndrome has become a high research priority. The impairment in facial recognition has been connected to a bias towards detail based processing (McPartland, Webb, Keehn & Dawson 2010). A recent study also connects this to an unusually high visual acuity, which could result in a disposition to focus on small facial features. In the present study. facial stimuli were prepared to provoke memory conjunction errors. This type of memory error means that a person erroneously claims to recognize a face assembled by pieces of previously shown stimuli. If a person is more prone to do so, that would imply that he or she is more focused on details than on configural information (Danielsson 2006). Two groups were tested, one consisting of non-diagnosed adults and one of adults diagnosed with Asperger Syndrome. A test for visual acuity was administered, which was followed by a series of facial recognition tasks. Responses in the latter part were given with a computer mouse, and eye fixations were recorded using a head mounted eye-tracking device. Three hypotheses were formulated. First, persons with AS were expected to perform more poorly in all facial recognition tasks. Second, persons with AS were expected to make more conjunction errors than test group subjects. Finally, persons with AS were expected to display a mean visual acuity significantly higher than that of the test group. However, no significant differences emerged between the groups in relation to either of the hypotheses, and results could not be referred to flaws in the experimental setup. Therefore, these results are taken to display the heterogeneity of the Asperger Syndrome population, and possibly the importance of early training measures to compensate for social impairments.

Avhandlingens övergripande syfte var att undersöka ansiktsigenkänning för personer med och utan utvecklingsstörning. Tre specifika forskningsfrågor undersöktes: 1. Hur ser interaktionen ut mellan familjaritet med ansikten och familjaritet med miljöer när det gäller bildigenkänning för personer med utvecklingsstörning? 2. Kan någon av de 2 teoretiska ansatserna till förklaring av falska minnen (sammanblandning av olika minnen), bindingsansatsen och dubbelprocessansatsen, förklara prestationen för både personer med och utan utvecklingsstörning? 3. Hur förhåller sig arbetsminnesförmåga till prestation i studier av falska minnen? Resultaten i de 4 artiklarna som ingår i avhandlingen gav svar på frågorna: 1. Interaktionen mellan familjaritet med personer och miljöer kan förklaras med förhållandet mellan personen och miljön, som antingen kan vara frånvarande, närvarande eller osannolikt. Dessa semantiska relationer bestämmer prestationen och en ”lat” semantisk strategi föreslogs. 2. Beroende på uppgiftens svårighetsgrad framkom olika interaktionsmönster mellan grupp och typ av igenkänningsbild, och då särskilt olika antal sammanblandade bilder. Dessa mönster kunde inte förklaras av någon av de 2 teoretisk ansatserna. Därför föreslås ett nytt sätt att tolka resultaten som inkluderar arbetsminne. 3. Hög arbetsminneskapacitet gav 2 effekter: för det första, igenkänning av fler ansiktsdelar, och för det andra, igenkänning av fler ansiktskonfigurationer. Vid höga arbetsminneskrav så används den första effekten mer på bekostnad av den andra. Det visade sig också att prestationen för personer med utvecklingsstörning på uppgifter med låga arbetsminneskrav liknade prestationen för åldermatchade kontrollpersoner utan utvecklingsstörning på uppgifter med höga arbetsminneskrav. Detta indikerar att utvecklingsstörning kan ”simuleras” genom högre arbetsminneskrav, åtminstone på denna typ av igenkänningsuppgifter. Resultatens implikationer för vittnespsykologi och användandet av fotografier som kognitivt stöd diskuteras. / The general purpose of this thesis was to investigate face recognition for persons with or without learning disability. Three specific research questions were investigated: 1. How does familiarity of faces interact with familiarity of environments in pictures for persons with learning disability? 2. Which, if any, of the 2 theoretical approaches to memory conjunction errors, the binding approach and the dual-processing approach, can explain performance for both persons with and without learning disability? 3. How does working memory relate to performance in memory conjunction error studies? The results of the 4 papers included in this thesis provided answers to the questions: 1. A person by environment interaction was found and was explained by an absent, present or implausible association between the person and the environment in the picture. These semantic relations determined performance and a “lazy” semantic strategy was suggested. 2. Different group by recognition type interaction patterns, and specifically different amounts of conjunction errors, were found for different degrees of task difficulty. These patterns could neither be explained by the dual processing approach nor the binding approach. Hence, a new frame of interpretation which included working memory was suggested. 3. High working memory capacity was associated with 2 effects: firstly, recognition of more facial features and, secondly, recognition of more facial configurations. At high working memory demands, participants relied on the first effect to a higher degree, at the expense of the other. It was also found that, in a task with low working memory demands, the performance for persons with learning disability was similar to the performance of age-matched controls with higher working memory demands in the task. This indicates that learning disability, at least in this type of recognition task, can be “simulated” by higher working memory demands in a population without learning disability. This finding is discussed in relation to witness psychology and the use of photographs as cognitive assistance.