The effect of mirthfulness upon amount of discordant right-left occipital EEG alpha

A total of 68 subjects participated in two experiments that tested the effect of exposure to comedy upon amount of discordant right-left occipital EEG alpha. Data from both showed less discordant alpha in the laughers and more in the nonlaughers at the end of exposure to a filmed comedy, as contrasted by no such group difference before treatment. Experiment 2 clarified that the production of discordant alpha in the right hemisphere was significant to this group difference, that this effect was specific to comedy treatment (nondiscriminative effects of exposure to a neutral film), and that a reversed group difference in amount of discordant right hemisphere alpha occurred after instructed hypoventilation (nondiscriminative effect of hyperventilation; counterbalanced order of all four treatments). The results were discussed in relation to (a) recent findings on right-left hemisphere characteristics of depressed individuals, (b) the significance of motivational states, (c) a link between cerebral blood flow and EEG indicators of activation, (d) ventilatory effects upon cortical activation, (e) personality differences inherent in tolerance for CO₂-blood concentration, and (f) recent findings on corticothalamic connections.     

Degree of consistent training: Improvements in search performance and automatic process development

Previous research has shown substantial improvements in detection performance when subjects consistently detect a subset of stimuli. In contrast, in conditions in which stimuli appear as both targets and distractors, there is little performance improvement with practice. The present experiments examine how varying degrees of consistency determine the improvement of detection accuracy with extended practice. The degree of consistency was varied by manipulating the frequency with which a letter was a distractor while holding the number of occurrences as a target constant. The experiments utilized a multiple-frame target-detection search paradigm in which subjects were to detect single-letter targets in a series of rapidly presented letters on four channels. Experiments showed that detection performance improvement with practice was a monotonic function of the degree of consistency, decreasing to zero as the target-to-distractor ratio increased from 10:0 to 10:20. As consistency decreased, detection performance asymptoted earlier and at a lower level. A dual-task experiment examined subjects’ ability to perform the previously trained search task as a secondary task. Results showed that the previous targetto-distractor consistency had a marked effect on resource sensitivity of the detection task. The general issues of consistency in the development of skilled performance and in the development of automatic processing are discussed.     

An indirect measure of perceived distance from oculomotor cues

The sensitivity of an indirect method of measuring perceived distance was compared in two experiments with the direct procedure of eliciting verbal reports of distance. Perceived distance was varied by varying the oculomotor cues to object distance. The indirect method, called the “adjustable pivot method,” uses an apparatus that physically moves the stimulus object laterally concomitantly with the lateral motion of the head. The magnitude and direction of this concomitant motion determines the distance of the point around which the direction of gaze to the object rotates (the pivot distance) as the head is moved. The pivot distance at which the object appears stationary with head movement measures the apparent distance of the object. Both types of measures were found to vary systematically with the oculomotor distance of the object for points of light (Experiment 1) and extended objects (Experiment 2). A previous study has shown that the adjustable pivot method avoids cognitive errors that can distort verbal reports of distance. The present study, by demonstrating the discriminative capability of this method under conditions in which differences in perceived distance were expected to occur, provides clear evidence that the adjustable pivot method is a sensitive and useful procedure for measuring perceived distance.     

The orthogonal transformations of a factorial matrix into itself

Certain matrix algebra, pertinent to multiple factor theory, is presented.