Separating the effects of interreinforcement time and number of interreinforcement responses

The relative importance of interreinforcement time and interreinforcement responses was evaluated by varying each independently. To do this, a blackout was presented after each nonreinforced response under both fixed-ratio and fixed-interval schedules of reinforcement. Manipulating the blackout duration under the fixed-ratio schedule caused interreinforcement time to vary without affecting the number of interreinforcement responses. Pigeons' post-reinforcement and post-blackout response latencies were found to increase linearly with interreinforcement time. Under the fixed-interval schedule, the same blackout manipulations changed the number of interreinforcement responses without affecting interreinforcement time. Post-reinforcement and post-blackout response latencies under this condition were approximately constant. These results suggest that responding is controlled by interreinforcement time and is not influenced by the number of responses emitted between reinforcements.     

A note on the nonmetric analysis of psychological intervals for an unknown ordering of stimuli

A modified version of a coordinate adjustment technique which permits the analysis of comparisons of psychological intervals for an unknown ordering of stimuli is described and compared to the original version and to TORSCA. For configurations with a large number of points, knowledge of the rank order of the stimuli does not improve the solution. For configurations with a small number of points, the performance of the new algorithm with an unknown ordering is equivalent to TORSCA.This research was supported by a grant from the Natural Sciences and Engineering Research Council of Canada.     

Developmental changes in infants' sensitivity to octave-band noises

Localization responses to octave-band noises with center frequencies at 200, 400, 1000, 2000, 4000, and 10,000 Hz were obtained from infants 6, 12, and 18 months of age. During an experimental trial, an octave-band noise was presented on one of two speakers located 45° to each side of the infant. A head turn to the noise (correct response) was rewarded by activating an animated toy on top of the speaker. The intensity of the noise was varied over trials (method of constant stimuli) to determine thresholds at each center frequency. Thresholds for the lower frequencies were approximately 5–8 db higher in the 6-month-old infants compared to the older infants. However, there were no consistent differences among groups at the higher frequencies. Infant thresholds were found to be 20–30 db higher than adult thresholds at the lower frequencies. At the higher frequencies thresholds for infants were approaching those of adults.     

Strategies for attention allocation in multiple input, multiple response tasks

9 tasks involving multiple inputs and multiple responses were administered. The tasks involved monitoring, shadowing, and ignoring, in all combinations, monaural and dichotic meassages. Miss rates were compared to determine the effect of adding additional demands to different tasks. Results suggested that, when a demand was added to a task, attention was allocated away primarily from those demands already receiving the greatest amounts of attention, to accommodate the new demand. When the new demand drew attention toward a channel, those demands already receiving the least amounts of attention gained the largest amounts. There were several exceptions to these trends, suggesting that the total amount of effort available for allocation was apparently an important variable. The implication of the results for research in attention was discussed.     

Assertiveness predicts threat and challenge reactions to potential stress among women.

In this study assertiveness as a moderator of stress reactions among women was examined. Specifically, the experimenters examined how high and low assertive women cognitively appraised, affectively and physiologically responded to, and behaviorally coped with the stress of giving an impromptu speech. High assertive women appraised the speech stressor as challenging, whereas low assertive women appraised the stressor as threatening. High assertive women also had a challenge pattern of autonomic response during the task, compared with the threat response of low assertive women. Afterward, the high assertive women reported experiencing less stress and negative emotion and greater positive emotion than did the low assertive women. Overall, the high assertive women's stress-related reactions indicated challenge, whereas the low assertive women's reactions indicated threat (see J. Tomaka, J. Blascovich, R. M. Kelsey, & C. L. Leitten, 1993).     

Visual-spatial working memory, attention, and scene representation: A neuro-cognitive theory

This paper addresses the issue of how visual-spatial working memory, attention, and scene representation are related. The first section introduces a modified two-stage conception of visual-spatial processing. “Stage one” refers to low-level visual-spatial processing and computes in parallel for the currently available retinal information “object candidates,” here called “visual-spatial units.” An attentional process called “unit selection” allows access to stage two for one of these units at a time. Stage two contains high-level visual-spatial information that can be used for goal-directions (e.g., verbal report, grasping). It consists of three parallel processing streams. First, the currently selected unit is recognized; second, a spatial-motor program for the selected unit is computed; and third, an “object file” is set up for the selected unit. An object file contains temporary episodic representations of detailed high-level visual-spatial attributes of an “object” plus an “index.” An index acts as a pointer and is bound via temporary connections to the attributes of the file. Section two of this paper specifies one part of stage two in more detail, namely visual-spatial working memory (VSWM). It can contain up to four object files. A first central claim is that during sensory-based processing for working memory (“access”), one object file is always “on-line,” and up to three other object files are “off-line”. A second central claim is that the process of setting up an object file depends on the number and the activation level of already stored files. Based on the concept of activation-based competition between object files, it is postulated that the more files that are stored and the higher their activation is, the longer it takes for a newly set up object file to reach a sufficient level of activation. Activation-based competition is also used to explain “short-term forgetting” by “interference.” A third central claim about VSWM is that a “refreshment' process exists that increases the activation level of an index of an object file in order to prevent forgetting or in order to bring the file back to the state of controlling the current action. Finally, section three gives a selective look at a number of experimental data such as the attentional blink, backward masking, dwell time effects, transsaccadic memory, and change blindness. New explanations are offered and new predictions made. Received: 16 January 1998 / Accepted: 25 July 1998     

Binocular vision enhances phase discrimination by filtering the background

Previous studies have shown that the detectability of a noise-masked target can be enhanced under stereoscopic viewing when the target’s interocular disparity differs from that of the noise. This enhanced detectability can be accounted for by a model postulating that the binocular system linearly sums the left-eye and right-eye views of a visual scene. This model also predicts enhanced phase discrimination under specifiable interocular disparities of target and noise. Two experiments were conducted in which subjects were asked to discriminate between two luminance patterns (target and foil) that differed only in phase. The target patterns were constructed by summating two vertical sinusoidal gratings in which the phase difference between the higher and the lower spatial frequency gratings was 45°. The foils contained the same two component frequencies, with a phase difference of ?45°. Thus, targets and foils were mirror images of one another. The ability of subjects to Discriminate between these stereoscopically viewed mirror-image patterns was investigated under two sets of interocular disparities: those that, according to our model, would unmask one or both spatial frequency components, and those that would leave both components masked by the noise. Phase discrimination was enhanced only when both component frequencies of the target and foil were unmasked. The implications of these findings for template-matching and phase-discrimination models of pattern discrimination are considered.     

Compulsive and addictive sexual disorders and the family

In the treatment of sexual addiction and compulsivity, the family unit is often neglected. Yet this disorder has a major impact not only on the identified patient, but also on the spouse or partner (the coaddict) and on the family as a whole. Moreover, the family unit is the context in which the sexual addict continues to live, and the mental health of the partner has a significant impact on the sexual addict's recovery. Increasing evidence points to a family history of addiction or dysfunction as a primary contributor to both sexual addiction and coaddiction in adulthood. When compulsive sexual behaviors are present within a family, treatment of both members of the couple improves the couple's relationship as well as the mental health of each partner. In addition, treatment of children in such a family can help break the cycle of sexual addiction and prevent its perpetuation into the next generation.