The effect of observing response procedures on the reduction of over-selectivity in a match to sample task: immediate but not long term benefits

Extension of the stimulus control produced by three procedures for teaching pseudowords discrimination

Abstract This study investigated the effects of pseudoword discrimination training that either required or didn’t require selection responses upon control by stimulus elements and recombination of elements, and upon stimulus observation. Eight undergraduate students were exposed to two conditions with discriminative training and stimulus control test. Condition SEL required selecting the S+, and condition OBS only required observation. Test results suggest that selection responses did not affect control by the elements or the recombination of elements in the pseudowords. Four participants presented restricted stimulus control. This control was extended in the additional DOR condition, which required differential observation of the elements, and was accompanied by increases in S+ observation. Increased stimulus control, promoted by the DOR, should still be evaluated independently of previous teaching conditions.

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.

Interference with facial emotion recognition by verbal but not visual loads

The ability to recognize emotions through facial characteristics is critical for social functioning, but is often impaired in those with a developmental or intellectual disability. The current experiments explored the degree to which interfering with the processing capacities of typically-developing individuals would produce a similar inability to recognize emotions through the facial elements of faces displaying particular emotions. It was found that increasing the cognitive load (in an attempt to model learning impairments in a typically developing population) produced deficits in correctly identifying emotions from facial elements. However, this effect was much more pronounced when using a concurrent verbal task than when employing a concurrent visual task, suggesting that there is a substantial verbal element to the labeling and subsequent recognition of emotions. This concurs with previous work conducted with those with developmental disabilities that suggests emotion recognition deficits are connected with language deficits.

Brief report: The effect of delayed matching to sample on stimulus over-selectivity

Stimulus over-selectivity occurs when one aspect of the environment controls behavior at the expense of other equally salient aspects. Participants were trained on a match-to-sample (MTS) discrimination task. Levels of over-selectivity in a group of children (4-18 years) with Autism Spectrum Disorders (ASD) were compared with a mental-aged matched typically-developing group. There was more over-selectivity in the ASD group. When retention intervals were added between the sample and comparisons in the MTS task, both groups showed an increased level of over-selectivity, with the ASD group showing a more pronounced effect.

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.

Comparison of conditioning impairments in children with Down syndrome, autistic spectrum disorders and mental age-matched controls

BACKGROUND

This study investigated the relative ease of learning across four tasks suggested by an adaptation of Thomas's hierarchy of learning in children with Down syndrome, autism spectrum disorders and mental age-matched controls.

METHODS

Learning trials were carried out to investigate observational learning, instrumental learning, reversal learning and conditional discrimination.

RESULTS

The sample with autism spectrum disorders performed worse than the other two groups on the observational learning and conditional discrimination tasks, while the Down syndrome sample performed worse on the instrumental learning task.

CONCLUSIONS

These findings are discussed in terms of there implications for reward-based educational intervention programmes.

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.

Age trends in stimulus overselectivity

Stimulus overselectivity refers to the phenomenon whereby stimulus control over behavior is exerted only by a limited subset of the total number of stimuli present during discrimination learning. It often is displayed by individuals with autistic spectrum disorders or learning disabilities, but is not exclusive to those groups. The present studies investigated the impact of aging on stimulus control and overselectivity. Three age groups--18-22, 47-55, and 70-80 year olds-were studied in two experiments. All participants were trained on a simple discrimination task, randomly assigned to one of two conditions (either with or without a distractor task), and then tested for the emergence of overselectivity (Experiment 1). In Experiment 2 responding controlled by the overselected stimulus elements was reduced by introducing a verbal punisher. In subsequent tests, control of behavior by the previously underselected elements from Experiment 1 was enhanced across the two younger age groups but not the oldest group of participants. The results are discussed in relation to the attention-deficit and overshadowing accounts of overselectivity.