Visual form recognition threshold and the psychological refractory period

Two experiments studied the effect of a reaction time response (RT) on visual form recognition threshold when the temporal interval separating the RT stimulus and the recognition stimulus was short. In Experiment 1 an initial RT response to an auditory signal did not impair the subsequent forced-choice visual form recognition threshold. Interstimulus intervals (ISI) of 0, 50, 100, 150, and 200 msec were used; S was always aware of the ISI under test. In Experiment 2 a visual stimulus was used to elicit the R T response; this shift to an intramodal stimulus did not alter the recognition threshold. These data were interpreted as supporting the hypothesis that two stimulus events can be processed simultaneously even when the temporal interval between them is short.     

Binocular fusion: A test of the suppression theory

Binocular fusion may be due to interocular inhibitory suppression, an hypothesis difficult to evaluate by phenomenal inspection. A test probe method (reaction time to a light pulse) was used to measure visual sensitivity during binocular rivalry and fusion. The absence of inhibitory effects during fusion fai Is to support the suppression theory of fusion.     

The Role of Candidate Sex in Voter Decision-Making

Recent studies investigating the role of candidate sex in voter decision-making have not found discrimination against women candidates. Thus, voter bias is often dismissed as part of the explanation for the drastic underrepresentation of women in high elective office. In a dual sample of Wyoming and California college students, bias against women candidates was found to be a factor in the vote choice. Studies that examine only one sample of voters in one region may be prematurely dismissing the possible existence of gender discrimination in some regions or cultures within the United States.     

COGENT: A visual design environment for cognitive modeling

COGENT is a design environment for modeling cognitive processes and systems. It permits psychologists to construct and test information-processing models of cognition based on traditional box-and-arrow diagrams. COGENT provides a graphical model editor, together with a set of standard types of cognitive module based on familiar theoretical constructs from psychological theory. Models are constructed by selecting appropriate box types, connecting them with appropriate communication links, and configuring the various boxes according to the requirements of the investigator. Once a model has been constructed, it may be executed to examine and analyze its behavior.     

Perceptual grouping and visual selective attention

The present study demonstrates that incongruent distractor letters at a constant distance from a target letter produce more response competition and negative priming when they share a target’s color than when they have a different color. Moreover, perceptual grouping by means of color, attenuated the effects of spatial proximity. For example, when all items were presented in the same color, near distractors produced more response competition and negative priming than far distractors (Experiment 3A). However, when near distractors were presented in a different color and far distractors were presented in the same color as the target, the response competition × distractor proximity interaction was eliminated and the proximity × negative priming interaction was reversed (Experiment 3B). A final experiment demonstrated that distractors appearing on the same object as a selected target produced comparable amounts of response competition and negative priming whether they were near or far from the target. This suggests that the inhibitory mechanisms of visual attention can be directed to perceptual groups/objects in the environment and not only to unsegmented regions of visual space.     

Perish and publish: non-heart-beating organ donation and unduly iterative ethical review

In the expanding repertoire of practices designed to increase the supply of organs for transplantation, non-heart-beating cadaver organ donation has generated an ongoing debate in the literature. The continuing stream of articles is disquieting in part because it documents a troubling "trial-and-error ethics" approach to the formulation of organ procurement policy, and because it raises serious questions about the reasons that the development of this policy is being mediated by published communication. In the light of concerns about the implicit support and credibility that professional publications give to organ procurement policies, restraint in publishing articles about non-heart-beating organ donation as well as in devising such policies is strongly advocated.     

Preserved word-stem-completion priming of semantically encoded information in Alzheimer's disease

Alzheimer's disease (AD) patients and normal elderly control subjects completed 80 standardized sentence frames with single words, yielding a measure of semantic memory. Memory for best fit sentence endings was then tested either explicitly, with a forced-choice recognition task, or implicitly, with a word-stem-completion task. The patients completed fewer sentences with best fit word endings than did the control subjects. Explicit retention was markedly defective in the AD group, but word-stem completion was normal. The preserved word-stem completion in AD is discussed in terms of encoding operations and transfer-appropriate processing.     

Temporal perturbations of binocular rivalry

Successive durations of binocular rivalry are sequentially independent, random variables. To explore the underlying control process, we perturbed the cycle during a 30-sec viewing period by immediately forcing an eye to return to dominance whenever it became suppressed. During this period of forced dominance, that eye's individual dominance durations were unusually brief, but immediately following the period of forced dominance that eye's suppression durations were unusually long. However, no long-term change in the sequential pattern of rivalry occurred, and the stochastic independence of successive durations was maintained during and following the period of forced dominance. The same pattern of results was obtained with even longer periods of forced dominance. These results are consistent with the existence of a short-term adaptation, or fatigue, process responsible for transitions from dominance to suppression.