R. Douglas Whitman

The utility of novelty seeking, harm avoidance, and expectancy in the prediction of drinking

To test the hypothesis that two temperament scales (Novelty Seeking and Harm Avoidance) are differentially related to alcohol expectancies and drinking patterns, 140 adolescents from an inpatient psychiatric facility completed several self-report questionnaires measuring temperament, alcohol expectancies, and alcohol consumption. Moderated multiple regression analyses indicated that Novelty Seeking was significantly related to frequency of drinking and problem drinking, but that Harm Avoidance was not related to these variables. Results of the MANOVA indicated that high novelty seeking and low harm avoidant (Type 2) individuals had a significantly higher frequency of drinking than did individuals who were high on Harm Avoidance and low on Novelty Seeking (Type 1). Results also showed that expectancy and Novelty Seeking contributed significant independent and overlapping variance in the prediction of amount of drinking. Although Novelty Seeking was related to expectations of social functioning, other hypothesized relationships between temperament and expectancy were not supported.

Subjective and objective assessment methods of mental imagery control: construct validation of self-report measures.

A study was conducted to examine the relationship between subjective and objective measures of mental imagery control. Eighty college undergraduates completed a battery of imagery tests and self-report measures to examine whether questionnaires that purport to measure imagery control or dynamic imagery ability (imagery of movement) would show a stronger relationship with objective measures of mental manipulation than would subjective measures that tap vividness of static imagery. Neither subjective measures of movement imagery nor subjective measures of stationary imagery showed meaningful relationships with objective measures of visuospatial manipulation. Additionally, subjective and objective imagery measures generally tended to dissociate. Basic component skills thought to be involved in mental manipulation, however, showed a much stronger relationship with the objective imagery tasks than did the self-report questionnaires. Findings suggest that subjective measures of imagery control do not tap the same cognitive processes involved in objective tests that require accurate imagery manipulation.

The unification of mind: Integration of hemispheric semantic processing

Seventy-six participants performed a visual half-field lexical decision task at two different stimulus onset asynchronies (50 or 750 ms). Word targets were primed either by a highly associated word (e.g., CLEAN-DIRTY), a weakly associated word (e.g., CLEAN-TIDY), or an unrelated word (e.g., CLEAN-FAMILY) projected to either the same or opposite visual field (VF) as the target. In the short SOA, RVF-left hemisphere primes resulted in high associate priming regardless of target location (ipsilateral or contralateral to the prime) whereas LVF-right hemisphere primes produced both high and low associate priming across both target location conditions. In the long SOA condition, contralateral priming patterns converged, demonstrating only high associate priming in both VF locations. The results of this study demonstrate the critical role of interhemispheric transfer in semantic processing and indicate a need to elaborate current models of semantic processing.

Reexamination of executive functions in psychosis-prone college students

Abstract The verbal and nonverbal executive functions of 19 psychosis-prone and 19 normal controls were examined. Subjects completed the WAIS-R Block Design and Vocabulary subtests, the Wisconsin Card Sorting Test (WCST), the Controlled Word Association Test (COWAT), the Booklet Category Test (BCT), the Design Fluency Test (DFT), and the Trail Making Test (TMT) parts A and B. Analysis of the performance patterns on these measures revealed that psychosis-prone college students exhibit relative deficits on all of the above verbal and nonverbal measures of executive functions but not on measures of nonexecutive functions. These findings confirm previously reported studies that have correlated executive functions and pre-frontal structural deficits with schizotypal personality traits and provide additional support for the association between neuropsychological functions and certain personality traits.

Spatio-temporal discrimination of frequency in the right and left visual fields: a preliminary report.

Normal right-handed subjects were presented with luminance patterns varying sinusoidally in both space and time to the left and right visual fields. With no temporal variation in the stimuli, detection thresholds for the left visual field were lower than those for the right visual field for all spatial frequencies. However, with increasing temporal variations, a reversal in detection of threshold occurred, with the right visual field surpassing the left. This finding suggests that left and right visual processing may be differentially efficient for temporal and spatial visual information.

Memory deficits in workers suffering from hard metal disease

This study examined memory functioning on the Wechsler Memory Scale-Revised in a group of adult tungsten carbide workers with hard metal disease and a group of matched controls. The hard-metal-exposed group of workers showed memory deficits related to difficulties in attention and verbal memory, with an apparent sparing of visual-spatial memory. Implications of this finding for future research are discussed.

Semantic activation within and across the cerebral hemispheres: What's left isn't right

This study examined differences in the spread of semantic activation within and between the cerebral hemispheres. A lateralised lexical decision task using indirect priming was presented to 58 undergraduates with primes and targets separated by 215 or 750 milliseconds (ms). Prime and target words were presented to the same or opposite visual fields and were either directly related (book–read), indirectly related (lion–[tiger]–stripes), or unrelated (cup–street). At 215 ms participants exhibited significant priming effects to directly related words in all conditions except when primes and targets were both presented to the right hemisphere (RH). In contrast, priming to indirectly related words was effective only when primes and targets were presented to opposite hemispheres. At 750 ms, significant priming occurred for directly related words in all conditions, and for indirectly related words when primes were presented to the RH. Results suggest that priming for directly and indirectly related concepts occurs unilaterally in each hemisphere before 215 ms. Both prime types activate semantic networks in the RH within 750 ms, whereas the LH processes information in a more focused manner. This suggests that activation spreads contralaterally from each hemisphere first to directly and then to indirectly related concepts, indicating the importance of incorporating contralateral priming contrasts in lexical decision tasks.

Role of subvocal motor activity in dichotic speech perception and selective attention.

Twenty right-handed male and female subjects were asked for ear-by-ear recall of dichotically presented consonant--vowel syllables. Stimuli within each dichotic pair were contrasted on the features on voicing and/or place, or were differentiated by manner of production. While listening to the stimuli, the subjects were required to concurrently reduce the electromyographic subvocal activity recorded from the lips and throat or from a control site, the frontalis muscle. A right-ear advantage was observed during the control condition, the largest advantage occurring when the pairs were contrasted on both voicing and place. In contrast, a left-ear advantage was observed when subvocal articulatory activity was voluntarily reduced. These results suggest that subvocal articulatory activity contributes to the observed right-ear advantage for speech by affecting attentional bias and not phonetic processing. Possible underlying mechanisms for this effect are discussed.

Gender Differences in Lateralized Semantic Priming

Previous literature suggests that women evidence more bilateral cerebral organization, particularly in language processing, whereas men show greater left hemisphere dominance for language. This study examined the magnitude of these gender differences in a lateralized lexical decision task and the implications of such differences to semantic processing and cerebral organization. As predicted, women, as compared to men, recruited greater bilateral hemispheric resources, as evidenced by greater contralateral hemispheric priming. Spatial skills predicted less priming in women, but not in men. Implications for laterality research in aging populations as well as future directions are discussed.

Memory deficits and industrial toxicant exposure: A comparative study of hard metal, solvent and asbestos workers

Memory functioning was examined in ex-factory workers with hard metal disease, resulting from exposure to alloys utilizing cobalt. Since these workers are also exposed to organic solvents and may suffer from chronic hypoxia as a result of their pulmonary disorder, solvent and asbestos workers, as well as an unexposed matched sample, served as controls. Results demonstrated deficits in the allocation of attentional resources and in short-term verbal memory. A pattern of findings across several tests suggested that repetition or delay is important for adequate memory performance in individuals exposed to hard metal, implicating a deficit in encoding or slowed consolidation.