The Effect of Stimulus Salience on Over-selectivity

Revaluation of overselected stimuli: Emergence of control by underselected stimuli depends on degree of overselectivity

Stimulus overselectivity describes strong control by one stimulus element at the expense of other equally relevant elements. Research suggests that control by underselected stimuli emerges following extinction of the overselected stimulus ("revaluation") and the emergence is larger when overselectivity is greater. We compared such revaluation effects with a control compound or condition in two experiments. Human participants chose between compound S+ and S- stimuli. Then, to assess control by compound-stimulus elements, participants chose between individual elements in a testing phase without feedback. The S+ element chosen most often (the overselected element) underwent revaluation, during which choice of that element was extinguished and choice of a novel element reinforced. Thereafter, participants completed a retesting phase. Revaluation reduced choice of the overselected element. Choice of the underselected element decreased for participants with low overselectivity but increased for participants with high overselectivity. This was not the case for a control compound that did not undergo revaluation (Experiments 1 and 2) or in a control condition in which the overselected element continued to be reinforced during revaluation (Experiment 2). These findings suggest that overselectivity levels may modulate revaluation effects, and they also highlight the importance of the contingency change in postrevaluation changes in stimulus control.

Visual attention affects late somatosensory processing in autism spectrum disorder

PURPOSE

Somatosensory processing problems are often reported in individuals with autism spectrum disorder (ASD), along with an abnormal multimodal integration of visual, tactile or proprioceptive information. However, the effects of visual stimulation and attention on somatosensory processing in ASD remain unknown. This study explores the effects of visual attention on somatosensory processing in ASD.

MATERIALS AND METHODS

The neural activity in somatosensory areas and associated regions was investigated by measuring somatosensory evoked potentials (SEPs) elicited by median nerve stimulation, in three different conditions (closed eyes, open eyes and focused attention to a visual task). Nine individuals with ASD and nine typically developing (TD) individuals participated in the study.

RESULTS

There were significant interactions between groups (ASD, TD) and conditions (closed eye, open eye, visual task requiring focused attention) for P100-N140 SEP amplitudes evaluated by 2-way analysis of variance. Post hoc analyses revealed that the P100-N140 amplitude with closed eyes recorded larger SEPs in the ASD group than in the TD group at C3' of the international 10-20 system. In the ASD group, the P100-N140 amplitude elicited smaller responses during visual tasks than with closed or open eyes. There were no significant differences in N20-P25 SEP components.

CONCLUSIONS

These findings suggest that visual attention affects the later stages of somatosensory processing in individuals with ASD.

Hierarchical Processing in ASD is Driven by Exaggerated Salience Effects, not Local Bias

The role of relative salience in processing of hierarchical stimuli in individuals with autism spectrum disorder (ASD) was examined in this study. Participants with ASD and typically developing controls performed a Navon letters task under conditions of global salience, local salience or equal salience of both levels. Results revealed no group differences in level of processing (global or local) and no local bias for ASD. Rather, both groups showed better performance when targets were more salient compared to when distractors were more salient. Importantly, participants with ASD exhibited increased sensitivity to salience at the distractor level. We conclude that inconsistent findings in the context of global/local processing in ASD may stem from such exaggerated salience effects.

Over-selectivity decreases with increased training: A role for within-compound associations

Over-selectivity occurs when one element of a complex-stimulus controls behavior at the expense of other equally elements of that stimulus; a phenomenon common in populations subject to cognitive challenge. However, lack of theoretically-based analysis, may have hindered understanding and remediation of the practically-important over-selectivity phenomena. Current studies examined whether associative theories applied to overshadowing, a similar phenomenon in the context of conditioning experiments, could be applied to over-selectivity effects to open theoretical analysis of over-selectivity. Three experiments investigated whether length of training impacts over-selectivity in the same way as overshadowing, which has theoretical implications for understanding that latter phenomenon. All studies employed variants of a judgment procedure in which participants had to judge the relationship between a predictor and an outcome, and the predictors were presented either on their own, or in compound with another predictor. In all studies, the elemental cue (A) was rated similarly to one of the components of the compound (B), but higher than the other component (C). The difference in the extent to which the components of the compound (B and C) were judged as predictors became smaller as levels of training increased, which is an effect that is also seen in discrimination learning studies of over-selectivity. Moreover, it was apparent that as the strength of the within-compound association increased, the level of over-selectivity decreased. These results are similar to those seen for overshadowing, and are discussed with respect to the possible associative mechanisms controlling over-selectivity.

The effects of concurrent cognitive task load on recognising faces displaying emotion

Two independent experiments (N = 30 and N = 24) investigated the effects of concurrent task loads on the recognition of faces displaying emotions. The study aimed to explore a possible resolution for an apparently discrepant finding in the literature regarding the impact of such loads on recognition of facial emotions. Faces displaying different emotions were presented, with or without a concurrent load, until the facial stimuli were correctly labelled to criterion in terms of the displayed emotion. Participants were then presented with elements from the faces (i.e. eyebrows, eyes, and mouth). When participants had to complete the concurrent task as well as the facial recognition task, they did not respond equally to the separate facial elements, and over-selected to the mouth when recognising facial expressions of emotion. The findings relating to the impact of the concurrent load tasks on correct labelling of the facial elements with respect to the emotional faces are discussed in terms of the impact of cognitive load on the production of over-selectivity and the recognition of faces displaying emotions in complex situations, and the implications for those with a developmental disability.

Diametric effects of autism tendencies and psychosis proneness on attention control irrespective of task demands

Our capacity to attend a target while ignoring irrelevant distraction impacts our ability to successfully interact with our environment. Previous reports have sometimes identified excessive distractor interference in both autism and schizophrenia spectrum disorders and in neurotypical individuals with high subclinical expressions of these conditions. Independent of task, we show that the direction of the effect of autism or psychosis traits on the suppression or rejection of a non-target item is diametrical. In Study 1, in which the presence of a salient non-target item hindered performance, higher autism traits were associated with better performance, while higher psychosis traits were associated with worse performance. In Study 2, in which the presence of a salient non-target item facilitated performance, a complete reversal of effects was observed. Future clinical interventions may be informed by the context-specific advantages we observed for the autism and psychosis spectra, and by the need to consider the diametric effects they yield.

Acquisition and Generalization of Complex Empathetic Responses Among Children with Autism

Empathy can be defined as a social interaction skill that consists of four components: (1) a statement voiced in the (2) appropriate intonation, accompanied by a (3) facial expression and (4) gesture that correspond to the affect of another individual. A multiple-baseline across response categories experimental design was used to evaluate the effectiveness of a prompt sequence (video modeling, in vivo modeling, manual and verbal prompting) and reinforcement to increase the frequency of complex empathetic responding by four children with autism. The number of complex empathetic responses increased systematically with the successive introduction of the treatment package. Additionally, generalization was demonstrated to untaught stimuli and a novel adult. Responding maintained over time to varying degrees for all participants. The data illustrate that children with autism can be taught using modeling, prompting, and reinforcement to discriminate between categories of affective stimuli and differentially respond with complex empathetic responses.

Over-Selectivity is Related to Autism Quotient and Empathizing, But not to Systematizing

The relationships of autism quotient (AQ), systematizing (SQ), and empathizing (EQ), with over-selectivity were explored to assess whether over-selectivity is implicated in complex social skills, which has been assumed, but not experimentally examined. Eighty participants (aged 18–60) were trained on a simultaneous discrimination task (AB+CD−), and tested in extinction on the degree to which they had learned about both elements of the reinforced (AB) compound. Higher AQ and lower EQ scorers demonstrated greater over-selectivity, but there was no relationship between SQ and over-selectivity. These results imply that high AQ scorers perform similarly to individuals with ASD on this cognitive task, and that over-selectivity may be related to some complex social skills, like empathy.

Autism Tendencies and Psychosis Proneness Interactively Modulate Saliency Cost

Atypical responses to salient information are a candidate endophenotype for both autism and psychosis spectrum disorders. The present study investigated the costs and benefits of such atypicalities for saliency-based selection in a large cohort of neurotypical adults in whom both autism and psychosis expressions were assessed. Two experiments found that autism tendencies and psychosis proneness interactively modulated the cost incurred in the presence of a task-irrelevant salient distractor. Specifically, expressions of autism and psychosis had opposing effects on responses to salient information such that the benefits associated with high expressions for autism offset costs associated with high expressions for psychosis. The opposing influences observed on saliency cost may be driven by distinct attentional mechanisms that are differentially affected by expressions for autism and psychosis.

Unsupervised categorization with individuals diagnosed as having moderate traumatic brain injury: Over-selective responding

PRIMARY OBJECTIVE

This study explored over-selectivity (executive dysfunction) using a standard unsupervised categorization task. Over-selectivity has been demonstrated using supervised categorization procedures (where training is given); however, little has been done in the way of unsupervised categorization (without training).

METHODS AND PROCEDURE

A standard unsupervised categorization task was used to assess levels of over-selectivity in a traumatic brain injury (TBI) population. Individuals with TBI were selected from the Tertiary Traumatic Brain Injury Clinic at Swansea University and were asked to categorize two-dimensional items (pictures on cards), into groups that they felt were most intuitive, and without any learning (feedback from experimenter). This was compared against categories made by a control group for the same task.

OUTCOMES AND RESULTS

The findings of this study demonstrate that individuals with TBI had deficits for both easy and difficult categorization sets, as indicated by a larger amount of one-dimensional sorting compared to control participants. Deficits were significantly greater for the easy condition.

CONCLUSIONS

The implications of these findings are discussed in the context of over-selectivity, and the processes that underlie this deficit. Also, the implications for using this procedure as a screening measure for over-selectivity in TBI are discussed.

Factors producing over-selectivity in older individuals

Stimulus over-selectivity describes a phenomenon where only a subset of the relevant stimuli present in the environment, control an individual's behavior. The current experiment explored the degree to which over-selectivity increases in old age. The level of over-selectivity in a visual discrimination task in 60 individuals aged 60-89 years was assessed, as well as the degree to which this reflected attentional control. In addition, the intellectual functioning and cognitive flexibility of the participants were assessed. Results showed that, as age increased, three effects were revealed: levels of stimulus over-selectivity increased, IQ scores decreased, and cognitive flexibility decreased. However, over-selectivity was not related to IQ or cognitive flexibility, and appeared related most to attentional impairments. Thus, ageing is related to significant declines in effective stimulus control. These effects can have a serious impact on the physical and psychological health of old adults, as well as their quality of life, and, therefore, this area of research warrants further exploration. The results are discussed in relation to the attention-deficit and comparator theory of over-selectivity.

Auditory-cued sensorimotor task reveals disengagement deficits in rats exposed to the autism-associated teratogen valproic acid

Autism Spectrum Disorder (ASD) is often found to co-exist with non-core behavioral manifestations that include difficulties in disengagement of attention to sensory cues. Here we examined whether this behavioral abnormality can be induced in rats prenatally exposed to valproic acid (VPA), a well-established teratogen associated with ASD animal models. We tested rats using an auditory-cued sensorimotor task (ACST) based on the premise that ACST will be more sensitive to developmental changes in temporal association cortex (TeA) of the posterior attention system. We show that VPA rats learned the ACST markedly faster than control animals, but they exhibited a profound preoccupation with cues associated with the expectancy at the reward location such that disengagement was disrupted. Control rats on the other hand were able to disengage and utilize auditory cues for re-engagement. However, both control and VPA-treated rats performed similarly when tested on novel object recognition (NOR) and novel context mismatch (NOCM) behavioral tasks that are known to be sensitive to normal perirhinal and prefrontal network functioning respectively. Consistent with disrupted posterior rather than frontal networks, we also report that VPA can selectively act on deep-layer TeA cortical neurons by showing that VPA increased dendritic density in isolated deep-layer TeA but not frontal neurons. These results describe a useful approach to examine the role of cue-dependent control of attention systems in rodent models of autism and suggest that disengagement impairments may arise from an inability to modify behavior through the appropriate use of sensory cue associations.

Atypical resource allocation may contribute to many aspects of autism

Based on a review of the literature and on reports by people with autism, this paper suggests that atypical resource allocation is a factor that contributes to many aspects of autism spectrum conditions, including difficulties with language and social cognition, atypical sensory and attentional experiences, executive and motor challenges, and perceptual and conceptual strengths and weaknesses. Drawing upon resource theoretical approaches that suggest that perception, cognition, and action draw upon multiple pools of resources, the approach hypothesizes that compared with resources in typical cognition, resources in autism are narrowed or reduced, especially in people with strong sensory symptoms. In narrowed attention, resources are restricted to smaller areas and to fewer modalities, stages of processing, and cognitive processes than in typical cognition; narrowed resources may be more intense than in typical cognition. In reduced attentional capacity, overall resources are reduced; resources may be restricted to fewer modalities, stages of processing, and cognitive processes than in typical cognition, or the amount of resources allocated to each area or process may be reduced. Possible neural bases of the hypothesized atypical resource allocation, relations to other approaches, limitations, and tests of the hypotheses are discussed.

Cross-modal attention-switching is impaired in autism spectrum disorders

This investigation aimed to determine if children with ASD are impaired in their ability to switch attention between different tasks, and whether performance is further impaired when required to switch across two separate modalities (visual and auditory). Eighteen children with ASD (9-13 years old) were compared with 18 typically-developing children matched with the ASD group for mental age, and also with 18 subjects with learning difficulties matched with the ASD group for mental and chronological age. Individuals alternated between two different visual tasks, and between a different visual task and an auditory task. Children with ASD performed worse than both comparison groups at both switching tasks. Moreover, children with ASD had greater difficulty when different modalities were required than where only one modality was required in the switching task in comparison with participants matched in terms of mental and chronological age.

Unsupervised Categorization in a sample of children with autism spectrum disorders

Studies of supervised Categorization have demonstrated limited Categorization performance in participants with autism spectrum disorders (ASD), however little research has been conducted regarding unsupervised Categorization in this population. This study explored unsupervised Categorization using two stimulus sets that differed in their difficulty of Categorization according to the simplicity model. ASD participants displayed a greater tendency to categorise according to one dimension as compared with mental-aged matched participants in the easily categorised sets, but both ASD and Control groups became more prone to one-dimensional sorting as the difficulty of the Categorization task increased. These results are discussed in terms of the processes underlying over-selective responding.

Revaluation manipulations produce emergence of underselected stimuli following simultaneous discrimination in humans

Stimulus overselectivity occurs when only one of potentially many aspects of the environment controls behaviour. In four experiments, human participants were trained and tested on a trial-and-error simultaneous discrimination task involving two two-element compound stimuli. Overselectivity emerged in all experiments (i.e., one element from the reinforced compound controlled behaviour at the expense of the other). Following revaluation (extinction) of the previously overselected stimulus, behavioural control by the underselected stimulus element emerged without any direct training of that stimulus element. However, while a series of extinction manipulations targeting the revaluation of the overselected stimulus produced differential extinction of that stimulus, they did not result in differential emergence of the previously underselected stimuli. The results are discussed with respect to the theoretical implications for attention-based accounts of overselectivity.

Effects of schedule of reinforcement on over-selectivity

Stimulus over-selectivity refers to behavior being controlled by one element of the environment at the expense of other equally salient aspects of the environment. Four experiments trained and tested non-clinical participants on a two-component trial-and-error discrimination task to explore the effects of different training regimes on over-selectivity. Experiments 1 and 2 revealed no differentiation between partial reinforcement (PR) and continuous reinforcement (CRF) on over-selectivity. Experiments 3 and 4 both found that a change in reinforcement (from CRF to PR in Experiment 3, and from PR to CRF in Experiment 4) did not reduce levels of over-selectivity, but rather continuing training with the same contingency (either CRF or PR) did reduce over-selectivity. The results support assumptions made by the comparator hypothesis, extending the growing body of literature explaining over-selectivity as a post-acquisition, rather than attention, failure.

Lack of evidence for inhibitory processes in over-selectivity

Stimulus over-selectivity can be defined as control over behavior being exerted by one aspect of the environment at the expense of other equally salient aspects of the environment, and is a common problem for discrimination learning under conditions of cognitive strain, and in intellectual disorders. Non-clinical participants exposed to a concurrent task load were trained and tested on a two-component trial-and-error discrimination task to investigate whether inhibition plays a role in producing under-selectivity by using both summation and retardation tests. Experiment 1 found evidence for the over-selectivity effect, and replicated the finding that revaluation of a previously over-selected stimulus allows emergence of control by a previous under-selected stimulus, despite the latter stimulus receiving no direct conditioning. The under-selected cue was not found to gain any conditioned inhibitory status, as reflected by summation (Experiment 2), and retardation (Experiment 3), tests. The results extend the literature explaining over-selectivity as a post-acquisition failure.

Factors impacting emergence of behavioral control by underselected stimuli in humans after reduction of control by overselected stimuli

Stimulus overselectivity occurs when only one of potentially many aspects of the environment controls behavior. Adult participants were trained and tested on a trial-and-error discrimination learning task while engaging in a concurrent load task, and overselectivity emerged. When responding to the overselected stimulus was reduced by reinforcing a novel stimulus in the presence of the previously overselected stimulus in a second trial-and-error discrimination task, behavioral control by the underselected stimulus became stronger. However, this result was only found under certain circumstances: when there was substantial overselectivity in the first training phase; when control by the underselected stimulus in the first phase was particularly low; and when there was effective reduction in the behavioral control exerted by the previously overselected stimuli. The emergence of behavioral control by the underselected stimulus suggests that overselectivity is not simply due to an attention deficit, because for the emergence to occur, the stimuli must have been attended to and learned about in the training phase; but that a range of additional learning factors may play a role.

Over-selectivity as a learned response

An experiment investigated the effects of different levels of task complexity in pre-training on over-selectivity in a subsequent match-to-sample (MTS) task. Twenty human participants were divided into two groups; exposed either to a 3-element, or a 9-element, compound stimulus as a sample during MTS training. After the completion of training, both groups were tested on an MTS task using a novel 6-element compound sample stimulus. The level of over-selectivity at test was influenced by the training. Specifically, the group exposed to a more complex (9-element) training task displayed higher levels of over-selectivity at test than the group with a less complex training task. The results suggest that over-selectivity may be a learned response to complex situations, and are discussed with respect to theories and treatments for over-selectivity.