Biomedical subjects

Melanie A Porter

Publications and source records attributed to Melanie A Porter.

3 recordsLinked to original sources

PubMed2006

Global and local processing in Williams syndrome, autism, and Down syndrome: perception, attention, and construction.

Global and local processing was studied in Williams Syndrome (WS), autism (AS), and Down Syndrome (DS) using perception, attention, and construction tasks. Past research has suggested an abnormal bias toward global processing in DS and, in contrast, an abnormal local bias in both WS and AS. Until now, no study has investigated whether the local processing bias in WS and AS has a different or similar underlying cause. Findings here suggest a common underlying mechanism, namely a bias in attention toward local processing. Results also indicate a global bias in attention in DS. This study finds no evidence to support predictions of the hierarchical deficit theory (Mottron & Belleville, 1993) as an explanation of hierarchical processing deficits in AS or DS, but does find support for hierarchical deficit theory in a subset of WS individuals. This study finds evidence of cognitive heterogeneity in WS, consistent with Porter and Coltheart (2005).

Adolescent↗

PubMed2005

Cognitive heterogeneity in Williams syndrome.

This study used the Woodcock-Johnson Tests of Cognitive Ability-Revised to investigate a wide range of cognitive abilities in people with Williams syndrome (WS). It involved a comparatively large sample of 31 people with WS, but took a case-series approach. The study addressed the widespread claims of a characteristic "WS cognitive profile" by looking for heterogeneity rather than homogeneity. People with WS showed a variety of preserved (significantly above mental age [MA]), expected (at MA), and significantly impaired (significantly below MA) levels of functioning. Such results provide clear evidence for heterogeneity in cognitive functions within WS. We found the most homogeneity on a test of phonological processing and a test of phonological short-term memory, with half of the WS sample performing at MA levels on these tests. Interestingly, no WS individual showed a weakness on a test of nonverbal reasoning, and only one WS individual showed a weakness on a test of verbal comprehension. In addition, we found that strengths on analysis-synthesis and verbal analogies occurred only for WS individuals with an MA less than 5.5 years (our sample median MA); people with an MA greater than 5.5 years performed at MA level on these 2 tests. Results also provided preliminary evidence for distinct subgroups of WS people based on their cognitive strengths and weaknesses on a broad range of cognitive functions. On the basis of the findings, caution should be made in declaring a single cognitive profile that is characteristic of all individuals with WS. Just as there is heterogeneity in genetic and physical anomalies within WS, not all WS individuals share the same cognitive strengths and weaknesses. Also, not all WS individuals show the profile of a strength in verbal abilities and a weakness in spatial functions.

Adolescent↗

PubMed2002

Self-control in honeybees.

Self-control means choosing a large delayed reward over a small immediate reward; impulsiveness is its opposite. The metabolic hypothesis states that the amount of self-control across species correlates negatively with metabolic rate (Tobin & Logue, 1994). Foraging honeybees have high metabolic rates; the metabolic hypothesis would predict little self-control in bees. But foraging bees work for the long-term good of their hive, conditions that seem to require self-control. In three experiments, we gave bees the choice between (1) a sweeter delayed reward and a less sweet immediate reward and (2) a large delayed reward and a small immediate reward. Bees showed much self-control, inconsistent with the metabolic hypothesis.

Animals↗