Is Source Memory Impairment Specific to Social Stimuli inHigh Funtionning Autism Spectrum Disorder?

Background: For the past thirty years, studies have tried to characterize the memory profile of individuals with autism spectrum disorders (ASD). Findings from the literature suggest they show deficits or atypical processing in episodic memory and more specifically in memorizing the source of information. Since the last decade, source memory has been increasingly investigated in individuals with ASD. However, contradictory findings have been found and the nature of source memory impairment in this population is still inconsistent.

Objectives: The aim of the current study is to better understand source memory functioning in children with High Functioning ASD (HF-ASD). To achieve this, limitations of previous research were addressed by using a theoretically driven task and an appropriate comparison group.

Methods: A group of 21 HF-ASD boys aged from 7 to 17 years old and their individually matched controls were assessed. Groups were matched on age, gender and verbal abilities. Memory was assessed using a theory driven experimental task designed to measure source memory for self-other (internal-external) and temporal context (external-external) of studied words (Doré et al., 2007).

Results: Discrimination indexes and response bias indexes were calculated based on the Two High Threshold Theory (Corwin, 1994). Groups comparison showed that the HF-ASD group is lower than the control group in discriminating self versus other source of previously presented targets (p <.05). There are no group difference on the identification of the temporal context (p = .21). Group comparisons also demonstrate that the HF-ASD group have lower recognition abilities in episodic memory (p <.05). Response bias indexes were similar between the two groups thus suggesting that both groups adopt a conservative approach when uncertain.

Conclusions: Findings confirm evidences from other studies that episodic memory seems impaired in children with HF-ASD. More importantly, our results point out to a particular profile of source memory processing in HF-ASD children. Analyses have shown that self-other source memory is impaired but not memory for temporal context. This finding support that source memory deficits are not generalized but may be more important when the to-be remembered source involves social aspects. To our knowledge no studies have yet examine how source memory may be related to the social impairments in children with HF-ASD.  This is of particular interest since social difficulties are a core deficit in HF-ASD. Further studies are actually in process in our laboratory to explore relations between source memory and social functioning in HF-ASD.