Arterial blood gases in Pranayama practice.

Pranayama is a Yogic breathing practice which is known experientially to produce a profound calming effect on the mind. In an experiment designed to determine whether the mental effects of this practice were accompanied by changes in the arterial blood gases, arterial blood was drawn from 10 trained individuals prior to and immediately after Pranayama practice. No significance changes in arterial blood gases were noted after Pranayama. A neural mechanism for the mental effects of this practice is proposed.     

Quantifiers and question answering in young children

Two hypotheses were tested about how young children answer questions with the quantifiers all and some: (a) that children use syntactic cues in determining which noun phrase is quantified, and (b) that children evaluate a some-statement as part of evaluating an all-statement. To test these hypotheses, the same group of 60 4- to 7-year-olds were asked four contrasting types of quantitative questions. The results indicated that children can use syntactic cues under some presentation conditions. However, there was no evidence for an asymmetry between the all-and some-questions. A model of how young children might answer quantitative questions was then considered.     

Suprathreshold binocular interactions for grating patterns

Binocular interactions of suprathreshold grating patterns have been investigated using a reaction time measure of contrast detection. Simple reaction times were determined for monocular and binocular viewing conditions over a contrast range from .63 to near threshold. The results from all subjects showed binocular summation for contrast levels near threshold, but there was considerable variation across subjects for contrast levels above threshold. Some subjects showed summation over the entire contrast range, but other subjects showed either binocular inhibition or binocular facilitation for some range of contrast levels. The pattern of binocular interaction for a given subject was consistent for several spatial frequencies. The differences in types of interaction between subjects, the variation in magnitude of binocular interaction with contrast level for each subject, and the data from experiments involving stimulation of noncorresponding retinal areas show that the binocular interactions found for suprathreshold stimuli cannot be accounted for on the basis of probability, and must, therefore, result from physiological interactions between the two eyes. These interactions have been investigated further under conditions of (1) induced fixation disparity, (2) horizontal gratings, and (3) orthogonally oriented gratings.     

The effects of delayed and displaced visual feedback on motor control

Developments in television technology have made possible new approaches to the study of the role of visual feedback in motor control. In two experiments using a special videodisc recording and playback system, the effects of delaying for 66 msec a subject's view of his own hand during a target-directed movement was investigated. The observed effects of such visually delayed feedback compared to spatially distorted feedback produced by prisms led to three major conclusions: (a) despite the behavioral similarity (overshooting) induced by the two kinds of altered feedback, the role of each in the visual-motor control loop is different; (b) adaptation to and the after effect of the two kinds of altered feedback are based on different control mechanisms (c) the processing and use of visual information in hand control requires less time than previous experiments have indicated.     

Cortical stimulation and speech timing: A preliminary observation

Audio recordings of the speech of seven patients receiving cortical stimulation during epilepsy surgery were acoustically analyzed, and duration measurements of the sound /s/ under stimulation and nonstimulation conditions were compared. It was found that in the dominant hemisphere, stimulation tended to significantly increase the duration of /s/; but not all stimulation sites were comparably affected. Stimulation of frontal lobe locations was also observed to more frequently result in durational increases than when temporal or parietal sites were stimulated. However, for sites affected, the actual magnitude of durational increase was comparable among the three lobes.