Immediate free recall in early childhood autism: another point of behavioural similarity with the amnesic syndrome

Relational memory weakness in autism despite the use of a controlled encoding task

Introduction

Recent work challenged past findings that documented relational memory impairments in autism. Previous studies often relied solely on explicit behavioral responses to assess relational memory integrity, but successful performance on behavioral tasks may rely on other cognitive abilities (e.g., executive functioning) that are impacted in some autistic individuals. Eye-tracking tasks do not require explicit behavioral responses, and, further, eye movements provide an indirect measure of memory. The current study examined whether memory-specific viewing patterns toward scenes differ between autistic and non-autistic individuals.

Methods

Using a long-term memory paradigm that equated for complexity between item and relational memory tasks, participants studied a series of scenes. Following the initial study phase, scenes were re-presented, accompanied by an orienting question that directed participants to attend to either features of an item (i.e., in the item condition) or spatial relationships between items (i.e., in the relational condition) that might be subsequently modified during test. At test, participants viewed scenes that were unchanged (i.e., repeated from study), scenes that underwent an "item" modification (an exemplar switch) or a "relational" modification (a location switch), and scenes that had not been presented before. Eye movements were recorded throughout.

Results

During study, there were no significant group differences in viewing directed to regions of scenes that might be manipulated at test, suggesting comparable processing of scene details during encoding. However, there was a group difference in explicit recognition accuracy for scenes that underwent a relational change. Marginal group differences in the expression of memory-based viewing effects during test for relational scenes were consistent with this behavioral outcome, particularly when analyses were limited to scenes recognized correctly with high confidence. Group differences were also evident in correlational analyses that examined the association between study phase viewing and recognition accuracy and between performance on the Picture Sequence Memory Test and recognition accuracy.

Discussion

Together, our findings suggest differences in the integrity of relational memory representations and/or in the relationships between subcomponents of memory in autism.

Counterfactual Reasoning and False Belief Understanding in Children with Autism

The Sally-Anne task used to assess children’s understanding of false belief has traditionally been conceptualized as a test of mental state understanding in that it asks the child where a protagonist thinks an object is located when the protagonist has a false belief about the object’s location. However, a recent logical analysis by Peterson and Riggs identifies a strategy for such tasks involving a specific reasoning process they term subtractive reasoning. This can be assessed by asking the child a question such as, ‘If the marble had not been moved, where would it be now?’ Studies of typically developing children have shown strong associations between false belief and subtractive reasoning tasks even when verbal mental age is controlled. In the present study we replicated these experiments using children with autism and children with severe learning difficulties. Although significant correlations between the two tasks were found for all three groups, analyses of contingencies between the two tasks and comparison of their respective difficulty for each group suggested that ability in subtractive reasoning was a necessary but not sufficient component of successful performance in the false belief tasks. Our results indicate the presence of a further factor which is required in these tasks, and which is deficient in autism, and we argue that this may consist in a specific type of generativity.

Executive Functioning and Memory Strategy Use in Children with Autism

An executive functioning deficit in autism should be reflected in a low level of active strategy use on memory tasks. This study was a direct examination of memory strategy use in two problem-solving situations by children with autism. Two groups with autism were tested, one high-functioning group and one with moderate cognitive impairments. All participants took part in two memory experiments to examine the effect of changing the nature of the learning situation on strategy use: one experiment used a serial recall task, and the other a recall readiness task. In contrast to previous studies, significant spontaneous strategy use was found on both memory tasks, particularly among the high-functioning group. Similarly, changing task structure was found to have an important impact on increasing strategy use, particularly for the moderate-functioning group. However, the overall rate of strategy use for the children with autism was still lower than would be expected for non-handicapped groups. The results support an executive functioning deficit interpretation, but a deficit that is less extensive among high-functioning individuals. Practical implications of the study in terms of cognitive training are also discussed.

Directed forgetting in high-functioning adults with autism spectrum disorders

Rehearsal strategies of adults with autism spectrum disorders (ASDs) and demographically matched typically developed (TD) adults were strategically manipulated by cueing participants to either learn, or forget each list word prior to a recognition task. Participants were also asked to distinguish between autonoetic and noetic states of awareness using the Remember/Know paradigm. The ASD group recognised a similar number of to-be-forgotten words as the TD group, but significantly fewer to-be-learned words. This deficit was only evident in Remember responses that reflect autonoetic awareness, or episodic memory, and not Know responses. These findings support the elaborative encoding deficit hypothesis and provide a link between the previously established mild episodic memory impairments in adults with high functioning autism and the encoding strategies employed.

Neuropsychological profile in high functioning autism spectrum disorders

A comprehensive investigation of the neuropsychological strengths and weaknesses of children with autism may help to better describe their cognitive abilities and to design appropriate interventions. To this end we compared the NEPSY-II profiles of 22 children with high-functioning autism spectrum disorders (HFASD) with those of 44 healthy control (HC) children 2:1 matched by gender, age, race and education. Results showed that only Visuospatial Processing was relatively spared in HFASD, while deficits were observed in Attention and Executive Functions, Language, Learning and Memory, and Sensorimotor Processing. Theory of Mind difficulties were observed in verbal tasks but not in the understanding of emotional contexts, suggesting that appropriate contextual cues might help emotion understanding in HFASD children. These widespread neuropsychological impairments reflect alterations in multiple cognitive domains in HFASD.

Assessing recollection and familiarity in low functioning autism

Methods to assess recollection and familiarity separately in autism spectrum disorder were recently developed and piloted (Bigham et al. in J Autism Dev Disord 40:878-889, 2010). The preliminary data obtained via these methods showed that whereas recollection was mildly impaired in high functioning autism, familiarity was spared. The current study set out to replicate the methods of assessment for recollection and familiarity devised by Bigham and her colleagues with individuals diagnosed with low functioning autism (LFA). Three critical modifications to the original paradigms were made within the current study. The modifications and implications of the findings for individuals with LFA will be discussed.

Episodic but not semantic order memory difficulties in autism spectrum disorder: evidence from the Historical Figures Task

Considerable evidence suggests that the episodic memory system operates abnormally in autism spectrum disorder (ASD) whereas the functions of the semantic memory system are relatively preserved. Here we show that the same dissociation also applies to the domain of order memory. We asked adult participants to order the names of famous historical figures either according to their chronological order in history (probing semantic memory) or according to a random sequence shown once on a screen (probing episodic memory). As predicted, adults with ASD performed less well than age- and IQ-matched comparison individuals only on the episodic task. This observation is of considerable importance in the context of developmental theory because semantic and episodic order memory abilities can be dissociated in typically developing infants before they reach the age at which the behavioural markers associated with ASD are first apparent. This raises the possibility that early emerging memory abnormalities play a role in shaping the developmental trajectory of the disorder. We discuss the broader implications of this possibility and highlight the urgent need for greater scrutiny of memory competences in ASD early in development.

Time-Based Prospective Memory in Children With Autism Spectrum Disorder

In this study, for the first time, prospective memory was investigated in 11 school-aged children with autism spectrum disorders and 11 matched neurotypical controls. A computerised time-based prospective memory task was embedded in a visuospatial working memory test and required participants to remember to respond to certain target times. Controls had significantly more correct prospective memory responses than the autism spectrum group. Moreover, controls checked the time more often and increased time-monitoring more steeply as the target times approached. These differences in time-checking may suggest that prospective memory in autism spectrum disorders is affected by reduced self-initiated processing as indicated by reduced task monitoring.

Episodische Gedächtnisleistungen bei Patienten mit Autismus-Spektrum-Störungen

Episodische Gedächtnisdefizite, wie etwa Abweichungen im Detailreichtum, in der Erinnerungshäufigkeit und –beeinflussbarkeit werden seit vielen Jahren bei Patienten mit Autismus-Spektrum-Störungen (ASD) beschrieben. Dabei sind Ursachen dieser Defizite noch relativ unerforscht. Vermutet werden Abweichungen in neuronalen Gedächtniskorrelaten wie dem Temporallappen (insbesondere Hippocampus), dem präfrontalen Kortex sowie dem Cingulum. Vorliegender Übersichtsartikel stellt Ergebnisse der normalen Entwicklung episodischer Gedächtnisleistungen bei Kindern und Jugendlichen sowie der experimentellen Gedächtnisforschung bei Patienten mit ASD vor. Klinische Implikationen für den Umgang mit repetitiven Fragen und eingeschränkten sozialen Konfliktlösemöglichkeiten auf Grund von Einschränkungen im episodischen Gedächtnis bei ASD werden diskutiert.

Temporal context memory in high-functioning autism

Episodic memory, i.e. memory for specific episodes situated in space and time, seems impaired in individuals with autism. According to weak central coherence theory, individuals with autism have general difficulty connecting contextual and item information which then impairs their capacity to memorize information in context. This study investigated temporal context memory for visual information in individuals with autism. Eighteen adolescents and adults with high-functioning autism (HFA) or Asperger syndrome (AS) and age- and IQ-matched typically developing participants were tested using a recency judgement task. The performance of the autistic group did not differ from that of the control group, nor did the performance between the AS and HFA groups. We conclude that autism in high-functioning individuals does not impair temporal context memory as assessed on this task. We suggest that individuals with autism are as efficient on this task as typically developing subjects because contextual memory performance here involves more automatic than organizational processing.

Neuropsychologic functioning in children with autism: further evidence for disordered complex information-processing

A wide range of abilities was assessed in 56 high-functioning children with autism and 56 age- and IQ-matched controls. Stepwise discriminant analyses produced good group discrimination for sensory-perceptual, motor, complex language, and complex memory domains but lower agreement for the reasoning domain than previously obtained for adults. Group discrimination did not occur for attention, simple language, simple memory, and visuospatial domains. Findings provide additional support for a complex information-processing model for autism, previously based on adult data, demonstrating a pattern across domains of selective impairments on measures with high demands for integration of information and sparing when demands were low. Children as compared to adults with autism exhibited more prominent sensory-perceptual symptoms and less pronounced reasoning deficits reflecting brain maturation.

Story Recall and Narrative Coherence of High-Functioning Children with Autism Spectrum Disorders

Previous research has found few quantitative differences between children with high-functioning autism spectrum disorders (ASDs) and well-matched controls in the length, complexity, and structure of their narratives. Researchers have noted, however, that narratives of children with ASDs have an unusual and idiosyncratic nature. This study provides an analysis of narratives in 17 children with high-functioning ASDs and 17 typically developing children matched on age, gender, language abilities, and cognitive abilities. We examined story recall and narrative coherence. The study revealed no group differences in story length or syntactic complexity. Children with ASDs also did not differ from controls in their use of the gist of a story to aid recall, or in their sensitivity to the importance of story events. Children with ASDs did, however, produce narratives that were significantly less coherent than the narratives of controls. Children with ASDs appeared less likely to use the gist of the story to organize their narratives coherently. These findings are discussed with regard to their relationship to other cognitive and linguistic difficulties of children with ASDs.

Long-term memory in high-functioning autism: controversy on episodic memory in autism reconsidered

Two studies were conducted to examine the nature of verbal long-term memory (LTM) in people with autism. In Study 1, undergraduate students showed better LTM and more verbal associations for concrete than abstract nouns. Probability of recall of the nouns strongly correlated with the number of associations with those nouns. In Study 2, unlike controls, autistic subjects did not show superior recall of concrete over abstract nouns despite overall comparable performance. A highly significant correlation between probability of recall and associative value was found only in the controls. Furthermore, there was an unusual correlation between LTM performance and a nonverbal measure in the autistic group. The results were discussed in terms of the relation between episodic memory and semantic memory.

Verbal association for simple common words in high-functioning autism

We investigated conceptual relationships in semantic memory using an indirect priming technique in high-functioning autistic adolescents and their controls who were matched for age, verbal IQ, performance IQ, and nonverbal reasoning ability. The prime was a single word and the target task was completing a word fragment that was semantically related or unrelated to the prime word. The autistic subjects and controls showed similar semantic priming effects, indicating intact conceptual relationships for simple common words in those with autism. Only in the autistic group was a significant correlation found between performance for the related items and two nonverbal cognitive measures, which suggests a possibility that semantic processing in individuals with autism might be qualitatively different from that in controls.

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.

Recall for self and other in autism: children's memory for events experienced by themselves and their peers

Research on memory processing suggests that memory for events that an individual experiences should be superior to that for similar events that someone else experiences (e.g., Baker-Ward et al., 1990). However, such predictions may not be applicable to individuals with autism. There are already suggestions that individuals with autism have specific difficulties in remembering (Boucher & Lewis, 1989). In addition, they are known to have more general difficulties involving processes related to the "self." If children with autism have difficulties in encoding information about themselves this could result in a deficit in personal episodic memory. The studies reported here compare memory for personally experienced events with that of memory for events experienced by a peer. An adaptation of a method devised by Boucher and Lewis has been employed to assess recall. Two separate studies were conducted to investigate whether children with autism are impaired at recalling personal events. Two groups of children took part in Study 1, a group of children with autism and a control group of typical children matched for verbal mental age. A group of children with moderate learning difficulties were employed in the second study to investigate whether the findings also occur in other groups of individuals who have learning disabilities. Findings indicate that, in the group with autism, events performed by the individual were recalled significantly less well than the observed events performed by a peer. However, the results for the nonautistic children in both studies showed that the opposite was true. Theoretical claims are discussed in the light of these findings.

Implicit and explicit memory in autism: is autism an amnesic disorder?

Medial temporal lobe amnesic disorder is characterized by an impairment in explicit memory (e.g., remembering a shopping list) and intact implicit memory (e.g., a woman seems familiar although you cannot remember having met her before). This study examined whether children with high-functioning autism have this same dissociation between explicit and implicit memory abilities. Children with autism and normal development participated in three memory tasks: one implicit task (perceptual identification) and two explicit tasks (recognition and recall). Children with autism showed intact implicit and explicit memory abilities. However, they did not show the typical pattern of recalling more items from both the beginning and end of a list and instead only recalled items from the end of the list. These results do not support the theory that high-functioning autism is a type of medial temporal lobe amnesia. However, these findings suggest that persons with autism use different organizational strategies during encoding or retrieval of items from memory.

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

Two experiments are described in which the memory of adults with Asperger's 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.

Working memory in children with autism and with moderate learning difficulties

We asked whether children with autism are specifically impaired on tests of working memory. Experiment 1 showed that children with autism were at least as likely as normal children to employ articulatory rehearsal (criterion: evincing the "word length effect") and that they had superior spans to that of children with moderate learning difficulties. In Experiment 2, participants were given "capacity tasks" in order to examine group differences in the capacity of the central executive of working memory. The performance of the children with autism was inferior to that of the normally developing group and similar to that of the children with moderate learning difficulties.

Generativity in the play of young people with autism

Examines the ability of young people with autism to generate ideas for play. Young people with autism, children with learning difficulties, and younger normal children were asked to generate 12 different actions and follow 12 instructions with a car and a doll. The young people with autism were impaired, relative to the controls, at generating original actions with the car, but were as able as the controls to follow the instructions. However, the young people with autism were not impaired at generating original actions with the doll. All three groups produced similar amounts of symbolic play. Possible explanations for the difference in results for the two toys are discussed.

Medial temporal lobe structures and autism: a review of clinical and experimental findings

Although substantive understanding of brain dysfunction in autism remains meager, clinical evidence as well as animal brain research on the effects of early damage to selective brain system have now yielded enough knowledge that some provisional hypotheses concerning the etiology of autism can be generated. Basically, the underlying premise of this review is that a major dysfunction of the autistic brain resides in neural mechanisms of the structures in the medial temporal lobe, and, perhaps, more specifically the amygdaloid complex. This review begins with a summary of clinical evidence of the involvement of the medial temporal lobe structures in autism. The major behavioral disturbances seen in monkeys that had received neonatal lesions of the medial temporal lobe structures are then described. From this survey it can be seen that distinct patterns of memory losses and socioemotional abnormalities emerge as a result of extent of damage to the medial temporal lobe structures. The potential value of the experimental findings for an understanding of neural dysfunction in autism as well as directions of future research are discussed in the final section of the review.

Autism: its primary psychological and neurological deficit

Autism is a perplexing condition because of its unique presenting signs and high degree of variability. Evidence is presented that the basic underlying information processing disorder is a dysfunction of the appreciation of the emotional significance of incoming stimuli and attaching motivational value to the stimuli. It is proposed that this dysfunction occurs when the amygdaloid nucleus and/or its connections are disrupted, resulting in the variability of the presentation of this syndrome among individuals. Herpes simplex encephalitis sometimes results in signs of autism. The virus has a predilection to attack specific areas of the brain, which provides information on the probable underlying neurological dysfunction in autism.

Memory impairments and communication in relatively able autistic children

Autistic people have specific memory difficulties. The effects of these difficulties on communication in relatively able autistic children and learning impaired controls were assessed in three experiments. The experiments tested the ability to: (1) carry out instructions; (2) ask questions without repetition; and (3) answer questions about past activities. When specific memory skills were required autistic children's communication was impaired relative to controls. When the need to use these skills was eliminated from the tasks the autistic children performed as well as controls. Some practical and theoretical implications of the findings are discussed.