Semantic, perceptual and number space: relations between category width and spatial processing.

Coarse semantic encoding and broad categorization behavior are the hallmarks of the right cerebral hemisphere's contribution to language processing. We correlated 40 healthy subjects' breadth of categorization as assessed with Pettigrew's category width scale with lateral asymmetries in perceptual and representational space. Specifically, we hypothesized broader category width to be associated with larger leftward spatial biases. For the 20 men, but not the 20 women, this hypothesis was confirmed both in a lateralized tachistoscopic task with chimeric faces and a random digit generation task; the higher a male participant's score on category width, the more pronounced were his left-visual field bias in the judgement of chimeric faces and his small-number preference in digit generation ("small" is to the left of "large" in number space). Subjects' category width was unrelated to lateral displacements in a blindfolded tactile-motor rod centering task. These findings indicate that visual-spatial functions of the right hemisphere should not be considered independent of the same hemisphere's contribution to language. Linguistic and spatial cognition may be more tightly interwoven than is currently assumed.

A Rasch analysis of three of the Wisconsin Scales of Psychosis Proneness: measurement of schizotypy.

Rasch analyses were conducted with data from 90 university students on three of the Wisconsin Scales of Psychosis Proneness--the Magical Ideation (Eckblad & Chapman, 1983), Perceptual Aberration (Chapman, Chapman, & Raulin, 1978), and Revised Social Anhedonia Scales (Eckblad, Chapman, Chapman, & Mishlove, 1982). All of the items for each of the individual scales, plus all of the items from the combined Perceptual Aberration/Magical Ideation (Per-Mag) Scale, showed satisfactory fit to the Rasch model. These results show that personality traits including these psychosis proneness, or schizotypy, traits can be measured on a theoretically sound quantitative interval scale. Rasch scale equivalents for raw scores are provided. Possible improvements to the Magical Ideation, Perceptual Aberration, and Per-Mag scales are suggested by the item analysis. Advantages of Rasch scaling for clinical applications include detection of invalid test protocols, more meaningful interpretations of test scores, and direct comparison of scores from different tests of the same construct.

Pervasive influence of semantics in letter and category fluency: a multidimensional approach.

We used multidimensional statistical procedures to study semantic and lexical processes underlying word retrieval in verbal-fluency performance. Forty healthy participants were given a two-choice letter task (i.e., generate items beginning with the letter 'A' or 'F', in any order) and a two-choice category task (i.e., generate animal or fruit names, in any order). Using correspondence analysis (CoA) and hierarchical clustering (HC), we found evidence of prominent semantic organization in both letter and category fluency. For example, a striking categorical segregation between animate and inanimate entities emerged during the letter task. Analysis of inter-item times revealed strong sequential priming effects in both tasks. Taken together, these results indicate that semantic facilitation is pervasive in word retrieval processes, even in the letter-fluency task, and therefore suggest that the traditional view of letter fluency as a purely phonemically based task should be revised. Finally, our findings may help explain patterns of verbal-fluency measures obtained in focal brain lesion patients.

Community integration following multidisciplinary rehabilitation for traumatic brain injury.

PRIMARY OBJECTIVE: To determine the extent to which participation in a multidisciplinary rehabilitation programme and patient characteristics predict improvement in community integration following mild-to-moderate traumatic brain injury (TBI). RESEARCH DESIGN: A non-randomized case-control study was conducted employing a pre-test-post-test multiple regression design. METHODS AND PROCEDURES: Archival data for 42 patients with mild-to-moderate TBI who completed the Community Integration Questionnaire (CIQ) at intake and again 6-18 months later were analysed. Half the sample participated in an intensive outpatient rehabilitation programme that provided multi-modal interventions, while the other half received no rehabilitation. The two groups were matched on age, education and time since injury. RESULTS: On the CIQ Home Integration scale, participation in rehabilitation and female gender predicted better outcome. On the Productivity scale, patients with a lower age at injury had better outcome. Outcome on both of these scales, as well as on the Social Integration scale, was predicted by the baseline pre-test score (initial severity). CONCLUSIONS: Overall, multidisciplinary rehabilitation appeared to increase personal independence. It is also concluded that: (1) multivariate analysis can reveal the relative importance of multiple predictors of outcome; (2) different predictors may predict different aspects of outcome; and (3) more sensitive and specific outcome measures are needed.

Are creativity and schizotypy products of a right hemisphere bias?

Prior research has shown associations between higher creativity (e.g., semantic association, verbal fluency), higher schizotypy (e.g., magical ideation), and relatively stronger right hemisphere laterality measures--when each of the three pairings has been studied individually. Our prior study related creativity and schizotypy to signal detection theory response criterion aspects of laterality. The present study attempted to integrate findings regarding these three constructs and to replicate the signal detection theory laterality results by providing measures of all three constructs in a within subjects design. Participants were 60 undergraduates who completed a test battery including two measures of creativity, three measures of schizotypy, a lateralized lexical decision task, and a dichotic listening task. Results are consistent with individual differences in creativity and schizotypy being partly related to a response criterion favoring right hemisphere, possibly nonconscious, processing. Dichotic listening results revealed a strong association of better right hemisphere (left ear) localization ability and creativity.