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.     

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.     

STIMULUS (INSTRUCTIONAL) FADING DURING EXTINCTION OF SELF-INJURIOUS ESCAPE BEHAVIOR

Three individuals with developmental disabilities were exposed to a series of assessment conditions to identify the source of reinforcement for their self-injurious behavior. In each case, self-injury occurred most often in instructional (demand) situations containing a brief time-out from the task contingent on self-injury, indicating that the behavior was an escape response (i.e., maintained by negative reinforcement). Treatment was implemented in a multiple baseline across subjects design and consisted of extinction (prevention of escape) plus instructional fading (initial elimination of instructions followed by their gradual reintroduction). Results showed that the combined treatment produced immediate and large reductions in self-injury that were maintained as the frequency of instructions was increased across sessions to match the original baseline rate of presentation. Results of a component analysis conducted with 1 subject suggested that stimulus fading accelerated the behavior-reducing effects of extinction.     

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.