Biomedical subjects

Rebecca Bull

Publications and source records attributed to Rebecca Bull.

7 recordsLinked to original sources

PubMed2006

Subitizing, magnitude representation, and magnitude retrieval in deaf and hearing adults.

This study examines basic number processing (subitizing, automaticity, and magnitude representation) as the possible underpinning of mathematical difficulties often evidenced in deaf adults. Hearing and deaf participants completed tasks to assess the automaticity with which magnitude information was activated and retrieved from long-term memory (using a Stroop-like paradigm to assess congruity effects), the representational format of magnitude information (by analysis of distance and Spatial Numerical Association of Response Codes effects), and the ability to rapidly enumerate small sets (subitizing). Both groups showed distance effects taken to indicate the use of a visual-spatial analog number line representing approximate quantity. Furthermore, both groups showed similar patterns of performance on the subitizing tasks and showed similar amounts of interference in an analysis of congruity effects. This is taken as evidence against the notion that idiosyncratic differences in basic number processing account for mathematical difficulties experienced by deaf individuals.

Adolescent↗

PubMed2006

Digit ratio (2D:4D) and the spatial representation of magnitude.

Digit ratio (as a putative indicator of prenatal androgen exposure) is related to a range of sexually dimorphic abilities, including spatial skills and mathematical ability. This study examined a phenomenon known as the SNARC effect (Spatial Numerical Association of Response Codes), which is taken as evidence of a mental representation of magnitude along a left-right-oriented number line, with low magnitudes associated with the left side of space, and high numbers with the right side of space. Participants made a parity judgement of numbers with responses made with a left key to odd numbers and a right key to even numbers. This was reversed for a second block of trials. Response times to numbers one to nine with both the right and left hand were calculated, and regression analyses conducted to analyse whether lower magnitudes were responded to faster with the left hand and higher magnitudes with the right hand. Participants with lower (more masculine) digit ratios on the right hand showed a stronger SNARC effect compared to participants with high digit ratios. This pattern of results was also found when the analyses were conducted separately for men and women. Results from left hand digit ratios indicated that only low digit ratio females showed a significant SNARC effect. These findings add to a growing literature on the relationship between digit ratio and cognitive abilities; in this case, simple cognitive representations that are accessed automatically rather than complex skills such as mental rotation or "mathematics" where a variety of solution strategies may be utilised.

Adolescent↗

PubMed2006

Measuring the development of executive control with the shape school.

Although several neurodevelopmental and psychiatric disorders can emerge during the preschool period, there are comparatively few instruments to assess executive control. Evidence for validity of the Shape School (K. A. Espy, 1997) was examined in a sample of 219 typically developing young children. There was good evidence for validity, as Shape School performance variables were interrelated and were associated to other criterion measures considered to measure aspects of executive control. Also suggesting validity, the Shape School variables varied as a function of whether the task demands (a) were executive, (b) required inhibition of a prepotent response or context-controlled selection among relevant stimulus-response sets, and (c) included unitary or concurrent processing. The Shape School may be an effective tool by which to measure executive control in young children who have atypical developmental patterns.

Attention↗

PubMed2005

Inhibitory processes in young children and individual variation in short-term memory.

A precise definition of executive control remains elusive, related in part to the variations among executive tasks in the nature of the task demands, which complicate the identification of test-specific versus construct-specific performance. In this study, tasks were chosen that varied in the nature of the stimulus (verbal, nonverbal), response (naming, somatic motor), conflict type (proactive interference, distraction), and inhibitory process (attention control, response suppression) required. Then performance differences were examined in 184 young children (age range = 3 years 6 months to 6 years 1 month), comparing those with high (5 or more digits) and low (3 or fewer digits) spans to determine the dependence on short-term memory. Results indicated that there was communality in inhibitory task demands across instruments, although the specific pattern of task intercorrelations varied in children with high and low spans. Furthermore, only performance on attention control tasks-that is, that require cognitive engagement/disengagement among an internally represented rule or response set that was previously active versus those currently active-differed between children of high and low spans. In contrast, there were differences neither between children with high and low spans on response suppression tasks nor on tasks when considered by type of stimulus, response, or conflict. Individual differences in well-regulated thought may rest in variations in the ability to maintain information in an active, quickly retrievable state that subserve controlling attention in a goal-relevant fashion.

Child↗

PubMed2004

A comparison of performance on the Towers of London and Hanoi in young children.

BACKGROUND: The Towers of London (TOL) and Hanoi (TOH) have been viewed as equivalent measures of planning and/or problem solving, although recent evidence in adults suggests that the underlying measurement characteristics of these two tasks may differ. As tower tasks are one of the few instruments that can be used to assess executive functioning in young children, the cognitive demands for both tasks merit further examination. METHODS: The relation among tower tasks and those of short-term memory, inhibition, and shifting ability were examined in a sample of 118 typically developing young children (M age = 4 years, 9 months, SD = 6 months). Half the children completed TOL and half completed TOH, with groups matched with respect to age, sex, and child vocabulary. RESULTS: Whilst performance on a shifting task uniquely predicted TOH performance, none of the executive function measures were related to TOL performance after statistically controlling for the influence of baseline naming speed. For both tower tasks, performance on a shifting task contributed more strongly on complex trials that required more moves in the counter-intuitive direction relative to the end-state goal, whereas inhibition task performance only predicted performance on complex TOL trials. CONCLUSIONS: Successful tower task performance may be determined, at least at higher levels of complexity, by mental flexibility in this age range. However, overall the findings suggest that TOL and TOH are not interchangeable tasks even in young children, and more generally, raise methodological issues regarding the complex nature of executive function tasks.

Age Factors↗

PubMed2004

Executive functioning in preschoolers: reducing the inhibitory demands of the dimensional change card sort task.

To investigate the role of inhibitory control in preschoolers' ability to switch sets, 3 conditions of the Dimensional Change Card Sort task ( Zelazo, Reznick, & Pinon, 1995) were tested. In Condition B (novel response options, standard stimuli) action inhibition was reduced, but the need for attentional inhibition was maintained. In Condition C (novel stimuli, standard response options) demands on both action and attentional inhibition were reduced. Performance in these was compared to that in the standard condition (A). Rule complexity was comparable across conditions. All 21 children who passed preswitch (average age 37 months) were tested on all postswitch conditions, order counterbalanced. Although reducing demands on action inhibition (Condition B) did not significantly improve performance, when demands on both action and attentional inhibition were reduced (Condition C) almost all children (95%) successfully switched sets (even children only 2 1/2 years old). Inadequate inhibition (of attention alone or both attention and action) appears sufficient to account for virtually all errors by preschoolers on this card sorting task.

Attention↗

PubMed2002

Positive mood and executive function: evidence from stroop and fluency tasks.

Contrasting predictions have been made about the effects of positive mood states on the performance of frontal lobe tests that tap executive functions such as inhibition, switching, and strategy use. It has been argued that positive mood is likely to improve some cognitive processes, particularly those dependent on the frontal cortex and anterior cingulate of the brain. However, there is some evidence that happy mood may impair executive functioning. The current experiments investigated the effects of positive mood on Stoop and fluency tests, which are frequently used to assess executive function. Positive mood impaired performance on a switching condition of the Stroop test, but improved performance on a creative uses test of fluency. The effect of positive mood on an executive task may therefore depend on whether a task is inherently motivating or is impaired by diffuse semantic activation.

Adolescent↗