Kevin John Riggs

Refining the understanding of inhibitory processes: how response prepotency is created and overcome

Understanding (a) how responses become prepotent provides insights into when inhibition is needed in everyday life. Understanding (b) how response prepotency is overcome provides insights for helping children develop strategies for overcoming such tendencies. Concerning (a), on tasks such as the day-night Stroop-like task, is the difficulty with inhibiting saying the name of the stimulus due to the name being semantically related to the correct response or to its being a valid response on the task (i.e. a member of the response set) though incorrect for this stimulus? Experiment 1 (with 40 4-year-olds) suggests that prepotency is caused by membership in the response set and not semantic relation. Concerning (b), Diamond, Kirkham and Amso (2002) found that 4-year-olds could succeed on the day-night task if the experimenter sang a ditty after showing the stimulus card, before the child was to respond. They concluded that it was because delaying childrens responses gave them time to compute the correct answer. However, Experiment 2 (with 90 3-year-olds) suggests that such a delay helps because it gives the incorrect, prepotent response time to passively dissipate, not because of active computation during the delay.

Executive control and the experience of regret

The experience of regret rests on a counterfactual analysis of events. Previous research indicates that regret emerges at around 6 years of age, marginally later than the age at which children begin to answer counterfactual questions correctly. We hypothesized that the late emergence of regret relative to early counterfactual thinking is a result of the executive demands of simultaneously holding in mind and comparing dual representations of reality (counterfactual and actual). To test this hypothesis, we administered two regret tasks along with four tests of executive function (two working memory tasks, a switch task, and an inhibition task) to a sample of 104 4- to 7-year-olds. Results indicated that switching, but not working memory or inhibition, was a significant predictor of whether or not children experienced regret. This finding corroborates and extends previous research showing that the development of counterfactual thinking in children is related to their developing executive competence.

The role of inhibitory control in the development of human figure drawing in young children

We investigated the role of inhibitory control in young childrens human figure drawing. We used the Bear-Dragon task as a measure of inhibitory control and used the classification system devised by Cox and Parkin to measure the development of human figure drawing. We tested 50 children aged between 40 and 64 months. Regression analysis showed that inhibitory control predicted development in human figure drawing even after the effect of age was excluded. These data suggest that inhibitory control plays a role in the development of childrens drawing and imply a relation between the executive functions and representational change.

How Do Alternative Ways of Responding Influence 3- and 4-Year-Olds' Performance on Tests of Executive Function and Theory of Mind?.

A total of 69 preschool children were tested on measures of false belief understanding (the Unexpected Transfer task), inhibitory control (the Grass/Snow task), and strategic reasoning (the Windows task). For each task, children indicated their response either by pointing with their index finger or by using a nonstandard response mode (pointing with a rotating arrow). The means of responding had no effect on childrens performance on the Grass/Snow task or on the Unexpected Transfer task, although children performed better on the Unexpected Transfer task when the key object in the story was removed. In contrast, performance on the Windows task was significantly better when children pointed with the rotating arrow. A follow-up experiment with 79 preschoolers found that this improved performance on the Windows task was sustained even after the nonstandard response mode was removed and children again pointed with their finger. These findings together suggest that nonstandard response modes do not help children to inhibit prepotent pointing responses but may help them to formulate response strategies on reasoning tasks by discouraging unreflective impulsive responding.

Young children retain fast mapped object labels better than shape, color, and texture words.

We compared short- and long-term retention of fast mapped color, shape, and texture words as well as object labels. In an exposure session, 354 3- and 4-year-old children were shown a set of two familiar and three novel stimuli. One of the novel stimuli was labeled with a new object label, color, shape, or texture word. Retention of the mapping between the new word and the novel object or property was measured either 5 min or 1 week later. After 5 min, retention was significantly above chance in all conditions. However, after 1 week, only the mappings for object labels were retained above chance levels. Our findings suggest that fast mapped object labels are retained long term better than color, shape, and texture words. The results also highlight the importance of comparing short- and long-term retention when studying childrens word learning.

Transcranial magnetic stimulation over left inferior frontal and posterior temporal cortex disrupts gesture-speech integration

Language and action naturally occur together in the form of cospeech gestures, and there is now convincing evidence that listeners display a strong tendency to integrate semantic information from both domains during comprehension. A contentious question, however, has been which brain areas are causally involved in this integration process. In previous neuroimaging studies, left inferior frontal gyrus (IFG) and posterior middle temporal gyrus (pMTG) have emerged as candidate areas; however, it is currently not clear whether these areas are causally or merely epiphenomenally involved in gesture-speech integration. In the present series of experiments, we directly tested for a potential critical role of IFG and pMTG by observing the effect of disrupting activity in these areas using transcranial magnetic stimulation in a mixed gender sample of healthy human volunteers. The outcome measure was performance on a Stroop-like gesture task (Kelly et al., 2010a), which provides a behavioral index of gesture-speech integration. Our results provide clear evidence that disrupting activity in IFG and pMTG selectively impairs gesture-speech integration, suggesting that both areas are causally involved in the process. These findings are consistent with the idea that these areas play a joint role in gesture-speech integration, with IFG regulating strategic semantic access via top-down signals acting upon temporal storage areas. SIGNIFICANCE STATEMENT Previous neuroimaging studies suggest an involvement of inferior frontal gyrus and posterior middle temporal gyrus in gesture-speech integration, but findings have been mixed and due to methodological constraints did not allow inferences of causality. By adopting a virtual lesion approach involving transcranial magnetic stimulation, the present study provides clear evidence that both areas are causally involved in combining semantic information arising from gesture and speech. These findings support the view that, rather than being separate entities, gesture and speech are part of an integrated multimodal language system, with inferior frontal gyrus and posterior middle temporal gyrus serving as critical nodes of the cortical network underpinning this system.

Seeing triggers acting, hearing does not trigger saying: evidence from children's weak inhibition.

There is evidence to suggest action imitation is automatic in adults and children. Childrens weak inhibitory control means that automatic activation can have dramatic effects on behaviour. In three developmental studies, we investigated whether verbal imitation, like action imitation, is automatic. In Experiment 1 (n=96), 3-year-olds accuracy was investigated on three well-established inhibitory tasks, and on a novel task which required the suppression of verbal imitation. Experiment 2 (n=48) compared 3-year-olds accuracy on well-matched action and verbal tasks. In Experiment 3 (n=96), 5-, 7- and 11-year-olds reaction times were compared on verbal and action tasks using conditions that enabled the tasks inhibitory demands to be assessed. Consistent support was found for verbal imitation being less automatic than action imitation. We suggest that this difference may reflect the greater complexity of speech, and has consequences for childrens behaviour and learning.

Parallels Between Action-Object Mapping and Word-Object Mapping in Young Children

Across a series of four experiments with 3- to 4-year-olds we demonstrate how cognitive mechanisms supporting noun learning extend to the mapping of actions to objects. In Experiment 1 (nxa0=xa061) the demonstration of a novel action led children to select a novel, rather than a familiar object. In Experiment 2 (nxa0=xa078) children exhibited long-term retention of novel action-object mappings and extended these actions to other category members. In Experiment 3 (nxa0=xa060) we showed that children formed an accurate sensorimotor record of the novel action. In Experiment 4 (nxa0=xa054) we demonstrate limits on the types of actions mapped to novel objects. Overall these data suggest that certain aspects of noun mapping share common processing with action mapping and support a domain-general account of word learning.

Cognitive correlates of pragmatic language comprehension in adult traumatic brain injury : A systematic review and meta-analyses

ABSTRACT Effective pragmatic comprehension of language is critical for successful communication and interaction, but this ability is routinely impaired following Traumatic Brain Injury (TBI) (1,2). Individual studies have investigated the cognitive domains associated with impaired pragmatic comprehension, but there remains little understanding of the relative importance of these domains in contributing to pragmatic comprehension impairment following TBI. This paper presents a systematic meta-analytic review of the observed correlations between pragmatic comprehension and cognitive processes following TBI. Five meta-analyses were computed, which quantified the relationship between pragmatic comprehension and five key cognitive constructs (declarative memory; working memory; attention; executive functions; social cognition). Significant moderate-to-strong correlations were found between all cognitive measures and pragmatic comprehension, where declarative memory was the strongest correlate. Thus, our findings indicate that pragmatic comprehension in TBI is associated with an array of domain general cognitive processes, and as such deficits in these cognitive domains may underlie pragmatic comprehension difficulties following TBI. The clinical implications of these findings are discussed.

Prepotency in action : does children’s knowledge of an artifact affect their ability to inhibit acting on it?

Prepotent actions are actions that are strongly triggered by the environment and so tend to be carried out unless intentionally avoided. Understanding what makes an action prepotent is central to an understanding of inhibitory control. The current study investigated actions made on artifacts because in artifact-dense cultures much everyday behavior is focused on them. A total of 80 3-year-olds were tested on a Go/No-go task that required children to make an action on go trials and to withhold it on no-go trials. These actions were made on artifacts with which the actions were either associated (e.g., drawing with a crayon) or unassociated (e.g., drawing with a hammer). Failure to avoid the go action on no-go trials was taken as evidence that the action was prepotent. Results suggested that an action did not need to be associated with an artifact in order for it to be prepotent (so drawing with a hammer could be prepotent). However, associated actions were sometimes produced even when children had been instructed to make an unassociated action. Children sometimes drew with a crayon when told to hammer with it, but they never hammered when told to draw.