Variation of the magnitude of the horizontal-vertical illusion with retinal eccentricity

The horizontal-vertical illusion was studied as a function of retinal eccentricity. It was found that the relation of illusion magnitude to vertical eccentricity is described by a U-shaped function with large amounts of reversed illusion for the more eccentric positions. Substantial effects due to horizontal eccentricity were also obtained, but these were not consistent across subjects. It is suggested that the flattening of the peripheral zones of the refracting surfaces of the eye may be involved in the variation of the illusion with retinal position, and that the astigmatic properties of the central portions of these surfaces may be a prime factor in the usual horizontal-vertical illusion.     

Visual discrimination of shape by Humans. II: (I) matrix figures and (II) minimal area changes

Two experiments are described in which an attempt was made systematically to vary two dimensional shapes according to a pre-arranged design. In the first, subjects were presented tachistoscopically with pairs of “reflexive matrix figures” whose members were either horizontally or vertically orientated; and it was found that reaction times to horizontal pairs were faster than to vertical ones, a result that is in keeping with previous findings. In the second experiment two ensembles were devised that were alike in every respect save that one group was extended or reduced vertically while the other varied horizontally. Performance was better on the vertically orientated ensemble. These findings are briefly related to former studies and the pre-eminence of vertical symmetry is underlined.     

Social uncertainty and interdependence: A study of resource allocation decisions in groups

Social uncertainty about the behavior of others with whom one is interdependent for rewards is hypothesized to encourage self-interested behavior and inhibit behavioral commitment to the group. This paper examines the roles of uncertainty, expectations, and feedback about other group members' contributions to the group in interdependent decision making. In the absence of feedback, resources tend to be divided between individual and group interests. Resource allocations to the group are found to increase significantly if group members receive feedback about other members' allocations, particularly if that feedback is at the individual level, not an aggregated group level. However, the effects of feedback presence and type are eliminated when group members state their expectations about other members' future contributions to the group. Implications for expectancy value theories of motivation and commitment to groups in organizations are discussed.     

MacLaboratory for Psychology: Successes,failures, economics,and outcomes over its decade of development

The history of the development of MacLaboratory for Psychology offers insights into both problems and solutions in academic software creation and implementation. Superficially, MacLaboratory for Psychology has been very successful, having garnered numerous acclamations, including two EDUCOM awards. It is used on thousands of Macintoshes at universities, hospitals, schools, and other institutions worldwide. However, there have also been some shortcomings to its use. In a candid discussion, successes, failures, the economics of software development, and student outcomes are addressed. Specific examples from the software as it has been used by over 10,000 undergraduates at Drexel University provide guidelines for future academic software in such domains as multimedia use, psychological and scientific education, classroom implementation, faculty research, and software support and maintenance.     

Attentional consequences of outcome-related motivational states: Congruent,incongruent, and focusing effects

Two experiments employed a game context to examine the effects of positive and negative feedback on the processing of targets varying in incentive properties. While half the targets carried no value, the others were assigned either a positive incentive value (where points could be gained) or a negative value (where points could be lost), and either a large incentive size (worth 5 points) or a small size (worth 2 points). Feedback from the previous trial was found to exert three effects on subsequent targets. A congruent effect appeared in the faster processing of large targets that matched the positive or negative valence of the previous feedback signal. An incongruent effect was evident in the delays in shifting attention from pretarget cues that contrasted in valence to the previous feedback. A focusing effect was reflected in the general delays following negative feedback in responding to targets with no value. In addition to these outcome influences, processing was generally more efficient for targets carrying positive than negative incentive value, and for targets of large than small size. These findings are discussed in terms of contemporary models of motivation and information processing.     

Charting the process of change: A primer on survival analysis

Survival analysis is a powerful and useful technique for understanding qualitative change. This article provides a practical, nontechnical introduction to the use of survival analysis for social scientists. Important issues in using survival analysis are discussed, including research design, data preparation and management, and data analysis. Attendance data from a self-helf organization are used to illustrate common survival analysis tasks such as describing the overall survival and hazard functions, examining covariate effects, and modeling the form of the hazard function over time. An appendix that discusses the strengths and weaknesses of current survival analysis computer programs is included. Editor's note: Edward Seidman served as action editor for this article while serving as Associate Editor for Methodology.I thank William Davidson, Susan Englund, Bruce Rapkin, Kurt Ribisl, and three anonymous reviewers for their helpful comments on earlier drafts. The example data presented here were collected with the support of an NIMH grant (MH37390) awarded to Julian Rappaport and Ed Seidman.