Biomedical subjects
Publications and source records attributed to Kevin J Riggs.
Using the Luck and Vogel change detection paradigm, we sought to investigate the capacity of visual working memory in 5-, 7-, and 10-year-olds. We found that performance on the task improved significantly with age and also obtained evidence that the capacity of visual working memory approximately doubles between 5 and 10 years of age, where it reaches adult levels of approximately three to four items.
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Understanding the operating characteristics of theory of mind is essential for understanding how beliefs, desires, and other mental states are inferred, and for understanding the role such inferences could play in other cognitive processes. We present the first investigation of the automaticity of belief reasoning. In an incidental false-belief task, adult subjects responded more slowly to unexpected questions concerning another person's belief about an object's location than to questions concerning the object's real location. Results in other conditions showed that responses to belief questions were not necessarily slower than responses to reality questions, as subjects showed no difference in response times to belief and reality questions when they were instructed to track the person's beliefs about the object's location. The results suggest that adults do not ascribe beliefs to agents automatically.
Go/no-go tasks seem to provide a simple marker of inhibitory development in young children. Children are told to respond to one stimulus on go trials but to make no response to another stimulus on no-go trials; responding on no-go trials is assumed to reflect a failure to inhibit the go response. However, there is evidence to suggest that a type of go/no-go task, which we call the "button-press" task, does not require inhibition. We investigated the conditions under which young children (M=3 years 6 months, N=120) experience inhibitory difficulty with this type of task. The data suggest that the speed of stimulus presentation is crucial and that other studies using this type of task have presented the stimuli too briefly. The importance of establishing the inhibitory credentials of a task before it is used as a marker of inhibitory control is emphasized.
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Using the format of a false belief task (Wimmer & Perner, 1983), we investigated the ability of 88 3- and 4-year-olds to ascribe a previously held true belief to a story protagonist. In an unexpected transfer task, children found true belief ascription as difficult as false belief ascription even though they could answer memory questions about story details. Results are discussed in relation to theoretical accounts of theory of mind development that stress the importance of understanding the falsity of belief, and those accounts that stress the importance of information or executive processes.
In a recent study Diamond, Kirkham and Amso (2002) obtained evidence consistent with the claim that the day-night task requires inhibition because the picture and its corresponding conflicting response are semantically related. In their study children responded more accurately in a dog-pig condition (see /day picture/ say "dog"; see /night picture/ say "pig") than the standard day-night condition (see /day picture/ say "night"; see /night picture/ say "day"). However, there is another effect that may have made the day-night condition harder than the dog-pig condition: the response set effect. In the day-night condition the names of the two stimuli ("day" and "night") and the two corresponding conflicting responses ("night" and "day") are from the same response set: both "day" and "night". In the dog-pig condition the names of the stimuli ("day", "night") and the corresponding responses ("dog", "pig") are from a different response set. In two experiments (Experiment 1 with 4-year-olds (n = 25); Experiment 2 with , 4-, 5-, 7- and 11-year-olds (n = 81)) children were tested on four experimental conditions that enabled the effects of semantics and response set to be separated. Overall, our data suggest that response set is a major factor in creating the inhibitory demands of the day-night task in children of all ages. Results are discussed in relation to other inhibitory tasks.
Children with autism were compared with control groups on their ability to make moral judgements. Participants were presented with pairs of vignettes in which actions were either deliberate or accidental and caused injury to a person or damage to property. Participants were asked to judge which protagonist was the naughtier and to verbally justify this judgement. Results showed that the children with autism were as likely as controls to judge culpability on the basis of motive, and to judge injury to persons as more culpable than damage to property. Children with autism also offered some appropriate verbal justifications for their judgments although most justifications were of poor quality and reiterated the story. Results are discussed in terms of theory of mind and the possible role of deficits in complex reasoning and executive functions.
The windows task is difficult for young children. In this task, a child is shown two boxes with windows revealing that one is empty, whereas the other contains a treat. The child is asked to point to a box for an opponent to look in. The child then "wins" the contents of the other box (the treat). To pass the task, the child must use a rule such as "point to the empty box." But crucially, because the child is not told this rule by the experimenter, he or she must first infer it. Therefore, the windows task has two distinct requirements: (a) infer the rule "point to the empty box" and, once the rule is inferred, (b) use the rule by holding it in mind while inhibiting the prepotent response of pointing to the treat. In this study, the authors sought to determine which of these two requirements was responsible for poor performance on the windows task. They compared the performance of 3(1/2)-year-olds (N=40) on four tasks: the standard windows task, a version of the windows task that required rule use but not rule inference, and two versions of the day-night task that also required rule use but not rule inference. The relative performance on these four tasks and the pattern of correlations among them suggested that children had difficulty in inferring a rule that enables them to pass the task, whereas they had little difficulty in using the rule. Little evidence was obtained to suggest that the standard windows task requires inhibition.
The contributions of counterfactual conditional reasoning (CCR), belief understanding, and inferential reasoning to the performance of children with autism (CWA) on standard false belief tasks were investigated. To assess the roles of these three factors, we compared the performance of CWA on physical-state CCR tasks (which do not require either an understanding of belief or inferential reasoning); on Wellman and Bartsch's (1988) nonstandard tests of false belief (which require an understanding of belief, but not CCR or inferential reasoning), and on standard tests of false belief tasks. The CWA were impaired relative to controls on the physical-state CCR and standard false-belief tasks, but not on the nonstandard false-belief tasks, and the CWA's performance on the physical-state CCR and standard false-belief tasks correlated highly, even when the effects of verbal ability were partialled out. Finally, the CWA's performance on standard false-belief tasks was more impaired than their performance on the physical-state CCR tasks. We concluded that impaired performance on standard false-belief tasks in autism is associated with defective competence in CCR (or some of its component skills), plus defective competence in inferential reasoning and possibly generativity, but that impaired performance is not caused by an inadequate understanding of belief. The results are discussed in relation to other hypotheses concerning the cause or causes of impaired performance on standard false-belief tasks in children with autism.