Increment thresholds against pulsed and steady backgrounds

Cornsweet and Pinsker reported that ΔL/L was constant at all values of L for briefly pulsed fields (ΔL was the luminance increment required for discriminating which of two nearby flashed fields was brighter). We obtain the same result when the subject must detect which of two briefly (4-msec) flashed backgrounds contains an increment at its center. However, when the background and increment are flashed at a longer duration (200 msec) ΔL/L decreases with increasing L as is obtained with a steady background. Two previous models which handle earlier work do not readily accommodate this result; we suggest a theoretical approach that does.     

Measuring the duration of perception

An analysis is presented of ways in which the total duration of perception of transient visual stimuli may be determined by means of psychophysical judgments of the simultaneity (or relative precedence) of two sensory events. This analysis yields a new method for measuring the duration of perception that only requires judgments of the simultaneity of the offset of one visual target with the onset of another (“offset-onset” judgments), and is thus free of differential biases between onset-onset and offset-onset judgments of simultaneity which could be involved in previous measurements. When three or more perceived durations need to be determined, the new method is more efficient than earlier methods; it requires measurement of only one PSE in order to evaluate one response duration as compared to two PSEs per response duration for previous methods. We also describe ways of determining the presence of some kinds of biases and quantitatively evaluating the magnitude of bias in the new method, as well as bias in onset-onset or offset-offset judgments of simultaneity alone; such evaluations of differential bias were not possible for the earlier methods. An experimental example of a bias analysis is described. No significant biasing effects were detected in the measures of perceived duration that were extracted as either retinal location or background luminance was changed, although background luminance itself markedly influenced the values of perceived duration.     

JAPANESE AND AMERICAN PERSONAL VALUES SOME CROSS-CULTURAL FINDINGS

Comparaison d'échantillons appariés d'étudiants japonais et américains (niveau lycée et collège universitaire) relativement aux six valeurs que mesure L'inventaire Survey of Personal Values. On a d'abord testé la comparabilité des “valeurs” dans la langue originale de L'inventaire et dans la traduction japonaise: L'analyse factorielle des items traduits et les corrélations calculées entre L'inventaire en japonais et un choix d'échelles japonaises de personnalité donnent des garanties à cet égard. Chez les étudiants japonais des deux sexes et des deux niveaux scolaires, on trouve des moyennes plus faibles pour ce qui est de L'orientation pratique de L'esprit, la réussite et la variété, et des moyennes plus élevées pour L'ordre et L'orientation vers un but. Ainsi, les Japonais accordent moins d'importance aux considérations matérialistes (réussite individuelle, changement ou diversité) mais ils donnent plus de valeur à un mode de vie organisé et routinier et au fait de chercher systématiquement à réaliser des buts bien définis. Les résul-tats de la présente recherche recoupant des recherches antérieures, font apparaître une grande ressemblance entre les deux pays, dans la structure de la personnalité.     

Firearm violence and the effects of gun control legislation

Two gun control laws designed to reduce different types of violent crimes were evaluated. In 1981, East St. Louis, IL, imposed stricter penalties for individuals who carry firearms outside their homes for protection (individuals could keep firearms in their homes). This law had only a temporary impact in reducing firearm use in assaults and robberies. In Evanston, IL, a slightly different approach was taken with legislation that banned handguns in the entire city (i.e., individuals could not keep handguns within their homes). A temporary reduction in firearm assaults occurred a few months before the gun law took effect. The implications of these findings are discussed.     

Are visual-perceptual and visual-motor skills separate abilities?

This study explored the independence of visual-perceptual and visual-motor abilities. Scores on the Motor-free Visual Perception Test were correlated by Pearson's method with scores on tests that weight the visual-perceptual, motor, and visual-motor components differently. Small but significant correlations were found between the Motor-free Visual Perception Test and tests of visual-motor integration, but there was no relationship between the motor-free test and tests of motor ability. These findings support the premise that tests of visual perception, visual-motor integration, and motor ability measure different skills.     

Simultaneity in Processing of Verbal and Spatial Information

Recent studies involving recall of verbal and spatial information produced conflicting results. In some cases investigators found males recalled verbal and spatial information equally well whereas females did less well on spatial than verbal information, but in other cases no sex differences were found. They also differed in that one study found processing of verbal and spatial information to be independent whereas others suggested trade-offs might occur. Using college-age subjects (17-25 yrs) with equal numbers of males and females (total n = 186) two experiments were performed to examine these differences. Although overall differences were found favoring verbal recall, females’ recall of spatial information was relatively poorer than males. Using a procedure designed to avoid possible artifactual depression of combined performance, we concluded that processing of spatial and verbal information is simultaneous in nature.

     

Saccade latency and warning signals: Stimulus onset,offset, and change as warning events

Two experiments investigated saccade latency to a peripheral target under various warning signal conditions. In Experiment I, the effects of warning stimulus onset, change, and two offset conditions were compared at warning intervals of 0, 100, 300, and 600 msec. Warning stimulus onset, change, and offset were all effective in reducing saccade latency as compared to a no-warning control condition, but warning stimulus offset resulted in shorter saccade latency than onset or change at all warning intervals. Experiment 2 compared onset and offset warning conditions at ?300-, ?250-, ?200-, ?150-, ?100-, ?50-, 0-, and 50-msec intervals. Responses following onset were slower than those following offset at the latter five intervals, while warning onset resulted in slower saccades than no-warning control conditions at ?150-, ?100-, and ?50-msec intervals. These results indicate that the onset of a visual warning signal can have an interfering effect on the programming or execution of a saccade.