Observations on regional cerebral blood flow in cortical and subcortical structures during language production in normal man

Regional cerebral blood flow (rCBF) was studied by single photon emission computerized tomography (SPECT) of inhaled xenon-133 in six normal volunteers during various language, articulatory, and control conditions. Language production increased rCBF in predominantly left-sided cortical and subcortical areas. The involved regions were anatomically related to a left frontal area (Broca's), to both caudate nuclei, to a left thalamic/pallidal area, and bilaterally in retrorolandic areas. The failure to demonstrate lateralized retrorolandic activity is thought to reflect the complexity of the tasks.     

Processing of visually presented vowels in the cerebral hemispheres

The respective efficiency of the cerebral hemispheres in processing visually presented vowels is discussed and examined in a tachistoscopic experiment with normal subjects. It is suggested that results from dichotic listening experiments cannot be used to predict performance on the same material in the visual modality. The physical characteristics of the stimulus, in both modalities, contribute to the pattern of hemispheric advantage and cannot be ignored in the interpretation of results from dichotic listening and tachistoscopic experiments.     

The relative contributions of predictiveness and salience in flavor aversion learning

Two experiments investigated the relative influence of cue predictiveness and stimulus salience on flavor aversion learning. In the first study experimental subjects experienced a nonsalient strawberry flavor and a different, more salient flavor prior to illness on each of the first three conditioning trials; the nonsalient strawberry and salient lemon were paired with illness on the fourth trial. This treatment resulted in a strong aversion to the strawberry flavor and on aversion to the lemon flavor. In contrast, animals which had experienced only a single pairing of strawberry, lemon, and illness acquired a strong aversion to lemon and no aversion to strawberry, while animals which had experienced only the pairing of different flavors and illness on each of the first three trials developed a strong aversion to both strawberry and lemon. Experiment 2 replicated the results of the experimental condition of the first study but also included a “blocking” condition in which subjects received three strawberry and illness pairings prior to a strawberry-lemon-illness pairing. Subjects in the blocking condition developed only a weak aversion to strawberry, and this aversion did not block the development of a strong lemon aversion. Apparently, in order for a nonsalient flavor cue to block the acquisition of an aversion to a more salient cue, the nonsalient flavor must not only be paired with illness but also be more predictive of illness than the more salient flavors also paired with illness. The data were discussed in terms of the R. A. Rescorla and A. R. Wagner's associative model (1972, in Classical conditioning II: Current research and theory, New York: Appleton-Century-Crofts), R. A. Rescorla's catalytic model (1982, Journal of Experimental Psychology: Animal Behavior Processes,8, 131–141), and N. J. Mackintosh's attentional model (1975, Psychological Review,82, 276–298) of conditioning.     

The mental effort requirement of cumulative rehearsal: A developmental study

Three experiments were conducted examining the relationship between the mental effort requirement of cumulative rehearsal and spontaneous utilization of the strategy by children. Mental effort was assessed by measuring the interference produced by cumulative rehearsal with a simultaneously performed secondary task (finger-tapping). It was found in Experiment 1 that second- and third-grade children experienced significantly more finger-tapping interference during instructed cumulative rehearsal than did sixth-grade children, an effect which, Experiment 2 demonstrated, could not be attributed simply to developmental differences in time-sharing performance. In Experiment 3 it was found that, for children in grades 2 through 5, rehearsal set size during spontaneous rehearsal was negatively correlated with amount of finger-tapping interference during instructed cumulative rehearsal, suggesting that spontaneous use of a cumulative rehearsal strategy was negatively correlated with the mental effort requirement of strategy use. These findings support the view that the mental effort requirement of strategy use may influence children's strategy selection on memory tasks.     

Regional cerebral blood flow patterns during verbal and nonverbal auditory activation

Current views of the relationship between audition and cerebral function suggest that increases in regional cerebral blood flow (rCBF) would occur in the superior, mid, and posterior portions of the temporal lobes, and that these changes would be more lateralized to the left hemisphere for a verbal than a nonverbal auditory task. We measured rCBF using the xenon inhalation technique in a group of healthy subjects during three conditions: (1) resting baseline, (2) auditory verbal activation (listening for word meaning), and (3) auditory nonverbal activation (listening for reduction of intensity in a series of noise bursts). Both verbal and nonverbal conditions produced highly significant increases in rCBF over the left posterior Sylvian region with a trend for verbal activation to evoke a wider area of flow increase than the nonverbal task.     

Dichotic testing of cerebral dominance in stutterers

Matched groups of right-handed male stutterers and controls received dichotic presentations of CVs and melodies on two occasions. Right ear advantages were obtained for CVs and left ear advantages for melodies, without significant differences between groups. However, a significantly greater number of stutterers than controls consistently failed to show the expected ear laterality for either type of material.     

Polydipsia induced by a schedule of brain stimulation reinforcement

Rats pressed a lever for a signaled brain stimulation reinforcement on either fixed-interval or fixed-ratio schedules. Both schedules induced polydipsia, with a median water intake of 22.5 ml (about four times the control level) in 3-hr sessions. The stimulation did not directly elicit drinking or other behaviors. In a second experiment, two out of four rats became polydipsic during extinction following a continuous schedule of brain stimulation reinforcement. The results were compared with previous attempts to induce polydipsia with a schedule of brain stimulation reinforcement and were discussed in terms of polydipsia as a model of human “compulsive” behaviors.     

Psychophysiological responsivity and the type A behavior pattern

Studies were reviewed in which the psychophysiological responses of Type A and B subjects were studied in various contexts. It appears that Type A's manifest greater psychophysiological arousal than Type B's in solitary as well as interpersonal situations in which there is a moderate external incentive to accomplish something. and there is an intermediate probability of failing to accomplish that something. Further, Type A's appear to manifest greater psychophysiological arousal than Type B's in interpersonal situations in which another person annoys or harasses the subject. Why Type A's respond in these situations with greater psychophysiological arousal was discussed in terms of the possibilities that (a) these situations may engage some defining characteristic(s) of Type A's, (b) Type A's may fear and therefore try to avoid failure more vigorously than Type B's, and (c) Type A's may be more motivated to gain and maintain control over important environmental events and therefore are more aroused by threats to such control than Type B's.     

An occupational taxonomy by professional characteristics: Implications for research

Theorists concerned with the nature of professionalism and researchers investigating professionals in the work environment often assume that professional occupations are a unique occupational type. To test this assumption, an occupational taxonomy based on nine dimensions of professionalism was derived empirically. The taxonomy represented expectations only to a moderate degree. Several implications were noted for the use of occupational taxonomies in the generalization of research findings on one occupational group to other occupational groups in the same classification.