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Biomedical subjects

R D Whitman

Publications and source records attributed to R D Whitman.

17 recordsLinked to original sources
PubMed1997

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.

Adult↗
PubMed1994

Facial recognition in hypothetically schizotypic college students. The role of generalized poor performance.

This study investigated facial and facial affect recognition abilities among hypothetically schizotypic college men, defined by high scores on the perceptual aberration, magical ideation, and schizotypy scales. Groups were commensurate in age, handedness, and general intelligence. Multiple analyses of variance revealed that high-scoring subjects, relative to control subjects, made more errors on a facial affect recognition task (F = 5.32, p < .05) and on a facial recognition task (F = 8.5, p < .01). Additional multiple analyses of covariance using the face recognition scores as the covariant found no group differences. These results extend similar findings in schizophrenic individuals to hypothetically schizotypic college students, and suggest that both groups exhibit affect recognition deficits that reflect generalized attention and vigilance deficits rather than a specific emotion recognition deficit.

Adult↗
PubMed1991

Efferent gating of human auditory attentional processes.

Brainstem evoked potentials were measured while subjects reduced either frontalis or lips/throat activity in response to visual information regarding EMG activity while attending to dichotically presented click stimuli. An inhibition of left ear activity occurred at the level of the cochlear nucleus (Wave 1) during articulatory muscle activity, suggesting that the right ear advantage is related to active inhibition of ipsilateral auditory pathways. Contralateral central inhibition of disattended information at the level of the brainstem (Wave 5) was also implicated. A neurophysiological model accounting for both attenuation of irrelevant stimuli and vigilance for high priority information is proposed.

Adult↗
PubMed1991

Lateralization of facial processing: a spatial frequency model.

Faces, filtered for either high or low spatial frequency components, were presented tachistoscopically to either the right or left visual fields. The right visual field presentations yielded more errors in a face matching task and this difference was greatest for low spatial frequency stimuli. Left visual field, low spatial frequency stimuli resulted in the fastest reaction times and the lowest error rates. These processing differences may reflect mechanisms underlying a wide range of hemispheric lateralization phenomena.

Adolescent↗
PubMed1990

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.

Cobalt↗
PubMed1989

Hemispheric asymmetry in the processing of high and low spatial frequencies: a facial recognition task.

The research investigated the relationship between spatial frequency and visual field in a facial recognition task. Faces of neutral affect (Ekman, 1979) were tachistoscopically presented to the right or left visual field. The faces were presented alone, or masked with square wave gratings of 1, 24, or 48 cycles/degree, for a duration of 10 msec. Accuracy in recognizing each target face from a group of five served as the dependent measure. Subjects were 15 males and 15 females. ANOVA results included a frequency x visual field interaction effect (p less than .001). As was hypothesized, LVF errors were highest in the absence of low spatial frequencies, while RVF errors were highest when a higher range of spatial frequencies was removed. These results confirm that the hemispheres show a differential efficiency in processing high and low spatial frequency information in faces. They also offer empirical evidence to support the clinical findings that both hemispheres contribute to facial recognition.

Adult↗
PubMed1984

Subvocal motor activity and contextual processing.

Twenty male and female subjects listened for mispronounced words while minimizing either subvocal or frontalis electromyographic activity. Stimuli were varied on size of the distortion, lexical constraint, and contextual constraint, all known to influence detections. Analysis of both the reaction time and detection data indicated that the minimization of subvocal EMG activity reduced or eliminated the effect of contextual constraint, effect. Results indicate that subvocal activity is related to contextual processing. Additionally, reaction time data are reported that indicate that although low contextual constraint greatly slows the decision process, detectability is actually superior. A possible underlying mechanism for this reversal of the speed-accuracy trade-off is discussed.

Attention↗
PubMed1981

Selective attention and laterally in good and poor readers.

Good and poor readers recalled lists of three pairs of competing digits presented either Dichotically (separated by ear) or Spectral-Monotically (separated by voice frequency) and at different rates of presentation. Poor readers showed a reduced ability to attenuate unattended channels and, unlike good readers, showed poorest performance at the fast rate. These results suggest a specific attentional deficit, not merely representative of the poor readers' general tendency to do poorly on difficult language related tasks.

Attention↗
PubMed1981

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.

Attention↗
PubMed1981

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 from 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.

Adult↗
PubMedDate not supplied

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.

Adolescent↗