Temporal integration differences between crossed and uncrossed stereoscopic mechanisms

In this study, we investigated temporal integration of disparity information for crossed and uncrossed stereopsis. Across three experiments, exposure duration thresholds were measured for stereoscopic stimuli created from dynamic random-dot stereograms. In Experiment 1, an investigation of disparity detection showed that detection thresholds were equal for the crossed and uncrossed directions. In Experiment 2, an examination of duration limits for depth perception showed that critical durations were lower, and depth more veridical, for crossed depth than for uncrossed depth. In Experiment 3, an investigation of depth discrimination revealed that discrimination thresholds were lower for crossed depth than for uncrossed depth. These results suggest that crossed and uncrossed mechanisms differ in terms of their temporal integration properties at processing levels involving the computation and discrimination of depth.     

Screening-off and The Levels of Selection

In The Levels of Selection (Brandon, 1984), Robert Brandon provides a suggestive but ultimately unsuccessful attempt to use the probabilistic notion ofscreening off in providing a schema for dealing with an aspect of the units of selection question in the philosophy of biology. I characterize that failure, and suggest a revision and expansion of Brandon's account which addresses its key shortcoming.     

A computer simulation model of rats’ place navigation in the Morris water maze

Rats rapidly learn to swim from a variety of starting locations, including novel ones, to a small invisible platform submerged in a pool of cool opaque liquid. A computer simulation based on a simple perceptual memory-matching model successfully mimics this ability. The model assumes that the rat, when it successfully reaches the platform, notes the distance to prominent extramaze landmarks and stores this perceptual information in memory. When placed in the pool on subsequent trials, the simulated rat attempts to match perceived distance between itself and the landmarks to the remembered distances from the platform to the landmark. The model accounts for many of the known facts about rats’ behavior in the swimming pool and makes some interesting predictions that could be easily tested experimentally. The model has the advantage, relative to other cognitive map models, of specifying how spatial information is represented in memory and how this information guides behavior.     

Millisecond interval timer and auditory reaction time programs for the IBM PC

Many types of behavioral research require the determination of elapsed time, for example to establish interstimulus intervals and to measure reaction time. The use of an IBM PC for on-line control of such applications is limited by the poor timing resolution ordinarily available. The IBM BIOS time information that is used for the BASIC TIMER function can result in interval timing errors as great as 110 msec. A machine language subroutine is described that can provide 1-msec accuracy. A BASIC program is also described that employs this subroutine to measure auditory reaction time.     

THE FAILURE OF FEEDBACK ON ALCOHOL IMPAIRMENT TO REDUCE IMPAIRED DRIVING

We examined the effects of rules to govern drinking, individual feedback on blood alcohol concentration (BAC), and public posting of group data on impaired driving on the incidence of impaired driving. Level of impairment was determined from breath samples taken from tavern patrons. Following baseline, an intervention package consisting of (a) cards to guide patrons in pacing their drinking to stay under the legal limit, (b) individual feedback on BAC, and (c) posted group feedback on the percentage of patrons driving while impaired the preceding week was introduced in two taverns. Results indicated that the intervention package did not reduce the percentage of impaired drivers departing either tavern. The addition of a brief intensive police enforcement program directed at impaired driving produced a short-term reduction in impaired driving.     

Response times for the CAGE,short-MAST,AUDIT, and JELLINEK alcohol scales

The CAGE alcohol screening tool has been touted as a good choice for clinical settings because of its brevity. We administered the CAGE and three other alcohol screening instruments (the Short-MAST, AUDIT, and JELLINEK) by microcomputer to 296 clients at a drinking driver treatment program and three of the four scales to a second sample of 270 clients from six drinking driver treatment programs. The average response times for the CAGE were 31 and 32 sec, respectively, in the first and second samples. The average response time for the JELLINEK was approximately five times longer than it was for the CAGE; response time for the AUDIT averaged four times longer; and response time for the Short-MAST was two and a half times as long. The estimated reliability of the CAGE was the lowest and its standard error of measurement was the highest of the four scales. We recommend the Short-MAST as the tool of choice if the extra minute of administration time it requires in comparison with the CAGE is not critical.     

Cognitive appraisal and attributional correlates of depressive symptoms in children

This study examined differences in cognitive appraisal and causal attributions in response to a task among schoolchildren reporting high and low depressive symptomatology. From a sample of 361 fifth- and sixth- grade students, 72 children were classified as depressed or nondepressed on the basis of their scores on the Children's Depression Inventory. They were then presented with modified Picture Arrangement problems from the WISC- R and questioned about their performance. Pretask expectations, evaluations, and future expectations of performance for the self and that of same- aged peers were assessed, as well as causal explanations for solvable and unsolvable problems. Despite similar performance, the depressed group of children provided lower evaluations for themselves than for others on all three measures of self- appraisal, whereas the nondepressed group did not show this tendency. Further, the attribution results indicated that the two groups differed in their explanations for failure, with the depressed group emphasizing the importance of ability in failure and the nondepressed group emphasizing factors other than ability. Overall, the results provide support for the presence of negative cognitions and self- defeating attributional style among depressed relative to nondepressed children, as well as pointing to the importance of social comparison processes in depression.This research was supported by studentships to Nancy Meyer from the Manitoba Health Research Council and subsequentlv from the Social Sciences and Humanities Research Council, and by a grant to Dennis Dyck from the Natural Sciences and Engineering Research Councel of Canada. The research was done in partial fulfillment of the first author's master's degree in the Department of Psychology at the University of Manitoba.We would like to thank Rhea Brooks, April Machej, and Colleen Singbeil, for their assistance in the study; John Schallow, John Whitely, Lillian Esses, and Mike Thomas, for their helpful suggestions; and the teachers, administrators, and parents of Assiniboine South #3 School Division, for their cooperation and support.     

MOVEMENT SUPPRESSION TIME-OUT FOR UNDESIRABLE BEHAVIOR IN PSYCHOTIC AND SEVERELY DEVELOP MENTALLY DELAYED CHILDREN

The effects of a movement suppression time-out, which involved punishing any movement or verbalization while a client is in the time-out area, were evaluated in four experiments. The first experiment examined the effects of a DRO procedure and movement suppression plus DRO in suppressing self-injurious behavior in a psychotic child in three different situations. In Experiment 2, the results of the previous experiment were replicated with two dangerous behaviors in a second psychotic child. In a third experiment, movement suppression plus DRO was compared with contingent restraint in reducing inappropriate poking behavior in two settings. The movement suppression procedure eliminated poking whereas contingent restraint had little effect. In the final experiment, movement suppression time-out alone was compared with exclusionary time-out alone and simple corner time-out alone. Self-stimulation occurred at high levels during the exclusionary and simple corner time-out procedures. Self-stimulation was either suppressed or reduced during movement suppression time-out. The movement suppression time-out procedure produced a larger reduction in the target behavior in all three children. The effectiveness of the movement suppression procedure was explained in terms of the suppression of self-stimulation while the time-out procedure was being applied.     

The development of race‐based perceptual categorization: skin color dominates early category judgments

Prior research on the development of race‐based categorization has concluded that children understand the perceptual basis of race categories from as early as age 4 (e.g. Aboud, 1988). However, such work has rarely separated the influence of skin color from other physiognomic features considered by adults to be diagnostic of race categories. In two studies focusing on Black–White race categorization judgments in children between the ages of 4 and 9, as well as in adults, we find that categorization decisions in early childhood are determined almost entirely by attention to skin color, with attention to other physiognomic features exerting only a small influence on judgments as late as middle childhood. We further find that when skin color cues are largely eliminated from the stimuli, adults readily shift almost entirely to focus on other physiognomic features. However, 6‐ and 8‐year‐old children show only a limited ability to shift attention to facial physiognomy and so perform poorly on the task. These results demonstrate that attention to ‘race’ in younger children is better conceptualized as attention to skin color, inviting a reinterpretation of past work focusing on children's race‐related cognition.