Dermot M. Bowler

Episodic Memory and Remembering in Adults with Asperger Syndrome

A group of adults with Asperger syndrome and an IQ-matched control group were compared in remember versus know recognition memory. Word frequency was also manipulated. Both groups showed superior recognition for low-frequency compared with high-frequency words, and in both groups this word frequency effect occurred in remembering, not in knowing. Nor did overall recognition differ between the two groups. However, recognition in the Asperger group was associated with less remembering, and more knowing, than in the control group. Since remembering reflects autonoetic consciousness, which is the hallmark of an episodic memory system, these results show that episodic memory is moderately impaired in individuals with Asperger syndrome even when overall recognition performance is not.

Asperger's syndrome and memory: Similarity to autism but not amnesia

Two experiments are described in which the memory of adults with Aspergers syndrome is compared with that of verbal IQ controls. The results of the first experiment showed that the Asperger subjects resembled autistic adults and children in their failure to use category information to aid their free recall. In the second experiment, both groups of subjects showed similar priming effects in an implicit stem completion task and similar performance on an explicit cued recall task. Moreover, both groups also showed more priming for items that they had read at study and better recall for items that they had to generate at study, suggesting that the cued recall of the Asperger subjects did not result from contamination by automatic or involuntary processes.

Episodic memory and episodic future thinking in adults with autism.

The ability to remember past experiences (episodic memory) is thought to be related to the ability to imagine possible future experiences (episodic future thinking). Although previous research has established that individuals with autism spectrum disorder (ASD) have diminished episodic memory, episodic future thinking has not previously been investigated within this population. In the present study, high-functioning adults with ASD were compared to closely matched typical adults on a task requiring participants to report a series of events that happened to them in the past and a series of events that might happen to them in the future. For each event described, participants completed two modified Memory Characteristics Questionnaire items to assess self-reported phenomenal qualities associated with remembering and imagining, including self-perspective and degree of autonoetic awareness. Participants also completed letter, category, and ideational fluency tasks. Results indicated that participants with ASD recalled/imagined significantly fewer specific events than did comparison participants and that participants with ASD demonstrated impaired episodic memory and episodic future thinking. In line with this finding, participants with ASD were less likely than comparison participants to report taking a field (first-person) perspective and were more likely to report taking an observer (third-person) perspective during retrieval of past events (but not during simulation of future events), highlighting that they were less likely to mentally reexperience past events from their own point of view. There were no group differences in self-reported levels of autonoetic awareness or fluency task performance.

Autism by another name? Semantic and pragmatic impairments in children

The literature on children with language disorders that are characterized by semantic and pragmatic impairments is reviewed and the conclusion is drawn that some of these conditions may stem from the same fundamental cognitive and interpersonal difficulties that are found in early childhood autism. A summary is presented of recent relevant research and theory in the field of autism and suggestions are offered on how these ideas might be applied to children showing semantic and pragmatic difficulties.

Free recall in autism spectrum disorder: The role of relational and item-specific encoding

Autism spectrum disorders (ASDs) are characterised by a relatively specific pattern of typical and atypical memory functioning. Convergent behavioural and neuroscientific evidence indicates that this pattern of functioning may be the result of specific impairments in hippocampally mediated relational memory processes, whilst brain-mechanisms mediating item-specific memory processes remain intact. In the current paper we draw on a behavioural paradigm developed by Hunt and Seta [Hunt, R. R., & Seta, C. E. (1984). Category size effects in recall—The roles of relational and individual item information. Journal of Experimental Psychology: Learning, Memory and Cognition, 10, 454–464], which not only allowed us to determine whether individuals with ASD did indeed experience selective difficulties in relational processes, but in addition enabled us to gain insights into the severity of this impairment. Our results suggest that whilst individuals with ASD employ relational memory processes atypically, this impairment seems restricted to situations in which such processes need to be deployed spontaneously to facilitate memory. Under situations that provide environmental support for the processing of relational information, individuals with ASD did demonstrate the ability to employ such processes relatively effectively. These findings provide further support for the ‘Task Support Hypothesis’ and suggest that relational memory processes may in principle be functionally intact despite not being triggered by the same environmental situations as in typical development.

Memory illusions : False recall and recognition in adults with Asperger's syndrome

As persons on the autistic spectrum are known not to use semantic features of word lists to aid recall, they might show diminished susceptibility to illusory memories that typically occur with lists of associated items. Alternatively, since such individuals also have poor source monitoring, they might show greater susceptibility. The authors found that adults with Aspergers syndrome (n = 10) recalled similar proportions of a nonpresented strong associate of the study list items, compared with controls (n = 15). In Experiment 2, rates of true and false recognition of study list associates did not differ significantly between Asperger (n = 10) and control (n = 10) participants. Moreover, the Asperger participants made fewer remember and more know judgments than controls for veridical but not for false recognitions. Thus, deficits found in some aspects of memory in people with Aspergers syndrome do not affect their susceptibility to memory illusions.

Factors affecting conscious awareness in the recollective experience of adults with Asperger's syndrome☆

have shown a small but significant impairment of autonoetic awareness or remembering involved in the episodic memory experiences of adults with Aspergers syndrome. This was compensated by an increase in experiences of noetic awareness or knowing. The question remains as to whether the residual autonoetic awareness in Asperger individuals is qualitatively the same as that of typical comparison participants. Three experiments are presented in which manipulations that have shown differential effects on different kinds of conscious awareness in memory in typical populations are employed with a sample of adults with Aspergers syndrome. The results suggest that the experiences of remembering reported by such individuals, although reduced in quantity, are qualitatively similar to those seen in the typical population. The results are discussed in the context of current theories of awareness in episodic memory.

Recognition Memory, Self-Other Source Memory, and Theory-of-Mind in Children with Autism Spectrum Disorder

This study investigated semantic and episodic memory in autism spectrum disorder (ASD), using a task which assessed recognition and self-other source memory. Children with ASD showed undiminished recognition memory but significantly diminished source memory, relative to age- and verbal ability-matched comparison children. Both children with and without ASD showed an “enactment effect”, demonstrating significantly better recognition and source memory for self-performed actions than other-person-performed actions. Within the comparison group, theory-of-mind (ToM) task performance was significantly correlated with source memory, specifically for other-person-performed actions (after statistically controlling for verbal ability). Within the ASD group, ToM task performance was not significantly correlated with source memory (after controlling for verbal ability). Possible explanations for these relations between source memory and ToM are considered.

On Mosaics and Melting Pots: Conceptual Considerations of Comparison and Matching Strategies

Conceptual and pragmatic issues relevant to the study of persons with autism are addressed within the context of comparison groups and matching strategies. We argue that no choice of comparison group or matching strategy is perfect, but rather needs to be determined by specific research objectives and theoretical questions. Thus, strategies can differ between studies in which the goal is to delineate developmental profiles and those in which the focus is the study of a specific aspect of functioning. We promote the notion of a “mosaic,” rather than a “melting pot,” approach to science in which researchers communicate conservative and precise interpretations of empirical findings.

Differential fear conditioning in Asperger's syndrome: implications for an amygdala theory of autism.

Since the first descriptions of individuals with autism spectrum disorders (ASD), abnormalities in socio-emotional behaviours have been described as amongst the most characteristic clinical features of this condition. Current evidence in this area suggests that individuals with ASD experience difficulties in the perception and expression of emotions within the social domain. The causes for these emotional difficulties are, however, still poorly understood. At the developmental level, it is unclear whether emotional disturbances constitute a primary feature of the clinical presentation of ASD or whether they are secondary to abnormalities in other areas of cognition. At the neurobiological level, it is still debated to what extent abnormalities of the limbic system, in particular the amygdala, may be responsible for the emotional disturbances characterising ASD. Here we show that a group of individuals with Aspergers syndrome exhibit a pattern of abnormality in differentially acquiring fear, which suggests that their fear responses are atypically modulated by conditioned and non-conditioned stimuli. On the basis of these results and the existing literature we suggest that ASD may be characterised by atypicalities in the integration of physiological and cognitive aspects of emotional experiences which we argue arise because of poor connectivity between the amygdala and functionally associated cortical areas.