ATTENUATED BINDING OF FEATURAL INFORMATION IN INDIVIDUALS WITH AUTISM SPECTRUM DISORDER

Background: Extensive evidence indicates that individuals from across the autism spectrum exhibit memory difficulties that mimic those observed in typical aging. For example, both populations show disproportionate difficulties on tests of free recall as compared to tests of recognition, both populations display impairments on episodic memory measures, and both groups exhibit problems in the sequential retrieval of information. This parallel is informative because it offers a useful heuristic device for further study and because it sheds light on possible neural mechanisms underlying the memory difficulties present in ASD.

Objectives: To further explore the usefulness of the aging analogy to the study of memory in ASD by drawing on a paradigm developed by Chalfonte and Johnson (1996). These authors showed that compared to younger participants, older typical adults had intact memory for individual features (i.e. colour, identity, location) of a complex stimulus (a grid of coloured line drawings) but were impaired in their memory for combined features (i.e. colour-identity, location-identity).

Methods: A sample of participants with ASD and typical individuals, matched on age and full-scale IQ, took part in the current investigation. On each of 5 separate testing sessions, participants were presented with 21 uniquely coloured line-drawings that appeared simultaneously for 1 minute in random locations of a 6x6 grid. Following Chalfonte and Johnson (1996), their memory was tested either for individual features only or for combinations of these features.

Results: Our results show that individuals with ASD in comparison to typical individuals exhibit a marked decrement in their memory for combinations of features despite showing intact memory for the features themselves.

Conclusions: Our findings further support a parallel between the memory difficulties evident in typically aging populations and those exhibited by individuals with ASD. We discuss these findings in the context of a ‘relational binding’ hypothesis of ASD.