Biomedical subjects

K Plaisted

Publications and source records attributed to K Plaisted.

6 recordsLinked to original sources

PubMed2001

Enhanced discrimination in autism.

Children with autism are superior to typically developing children at visual search tasks (O'Riordan, Plaisted, Driver, & Baron-Cohen, in press; Plaisted, O'Riordan, & Baron-Cohen, 1998b). This study investigates the reasons for this phenomenon. The performance of children with autism and of typically developing children was compared on a series of visual search tasks to investigate two related problems. The first issue was whether the critical determinant of search rate in children is the discriminability of the display items, as it is in normal adults. The second question investigated was whether the superior performance of individuals with autism on visual search tasks is due to an enhanced ability to discriminate between display items. The results demonstrated that discriminability is the rate-determining factor for children with and without autism, replicating earlier findings with normal adults, and that children with autism have an enhanced ability to discriminate between display items. Thus, it seems that an enhanced ability to discriminate between display items underlies superior visual search in autism.

Autistic Disorder↗

PubMed1999

Recognition of faux pas by normally developing children and children with Asperger syndrome or high-functioning autism.

Most theory of mind (ToM) tests are designed for subjects with a mental age of 4-6 years. There are very few ToM tests for subjects who are older or more able than this. We report a new test of ToM, designed for children 7-11 years old. The task involves recognizing faux pas. Study 1 tested 7-9, and 11-year-old normal children. Results showed that the ability to detect faux pas developed with age and that there was a differential developmental profile between the two sexes (female superiority). Study 2 tested children with Asperger syndrome (AS) or high-functioning autism (HFA), selected for being able to pass traditional 4- to 6-year level (first- and second-order) false belief tests. Results showed that whereas normal 9- to 11-year-old children were skilled at detecting faux pas, children with AS or HFA were impaired on this task. Study 3 reports a refinement in the test, employing control stimuli. This replicated the results from Study 2. Some patients with AS or HFA were able to recognize faux pas but still produced them. Future research should assess faux pas production.

Asperger Syndrome↗

PubMed1999

Children with autism show local precedence in a divided attention task and global precedence in a selective attention task.

Children with a diagnosis of autism and typically developing children were given two variations of the Navon task (Navon, 1977), which required responding to a target that could appear at the global level, the local level, or both levels. In one variation, the divided attention task, no information was given to children regarding the level at which a target would appear on any one trial. In the other, the selective attention task, children were instructed to attend to either the local or the global level. Typically developing children made most errors when the target appeared at the local level whereas children with autism made more errors when the target appeared at the global level in the divided attention task. Both groups of children were quicker to respond to the global target than the local target in the selective attention task. The presence of normal global processing in the children with autism in one task but not in the other is discussed in terms of a deficit in mechanisms that inhibit local information in the absence of overt priming or voluntary selective attention to local information.

Adolescent↗

PubMed1998

Enhanced discrimination of novel, highly similar stimuli by adults with autism during a perceptual learning task.

High-functioning adults with autism and control adults were tested on a perceptual learning task that compared discrimination performance on familiar and novel stimuli. Control adults were better able to discriminate familiar than novel stimuli--the perceptual learning effect. No perceptual learning effect was observed in adults with autism although they discriminated the novel stimuli significantly better than control adults. This enhanced discrimination learning about novel, but not familiar, stimuli in autism is discussed in relation to two current hypotheses of information processing in autism--weak central coherence and reduced attention-switching--and a new third hypothesis, which suggests that features held in common between stimuli are processed poorly and features unique to a stimulus are processed well in autism.

Adult↗

PubMed1998

Enhanced visual search for a conjunctive target in autism: a research note.

Children with and without autism were compared on two visual search tasks in which a letter target appeared among two sets of letter distracters. In one task, the target shared colour with one set of distracters but was unique in shape--the feature search task. In the other, the conjunctive search task, the target shared colour with one set and shape with another set of distracters. Although search was slower in the conjunctive task than the feature task in normally developing control children, children with autism showed no significant slowing in reaction time in the conjunctive task and were faster than control children in this task. This result is discussed in the light of theories of visual search which state that rate of search is determined by the degree of similarity between target and distracters.

Attention↗

PubMed1994

Latent inhibition, context specificity, and context familiarity.

In two appetitive licking experiments, thirsty rats were pre-exposed on two stimuli prior to conditioning sessions in which one or both of these stimuli were paired with water. Consistent with other results, latent inhibition was disrupted when conditioning took place in a context different from that in which stimulus pre-exposure had occurred. But in animals given prior exposure to the context of stimulus pre-exposure before the start of stimulus pre-exposure, substantial and equivalent latent inhibition was evident whether or not there was a change of context between stimulus pre-exposure and conditioning. These results are discussed in terms of current theories of latent inhibition.

Animals↗