Agreement between observers when the categories are not specified in advance

To test the agreement between two observers who categorize a number of objects when the categories have not been specified in advance, Brennan & Light (1974) developed a statistic A′ and suggested a normal approximation for its distribution. In this paper it is shown that this approximation is inadequate particularly when one, or both, of the observers place a fairly equal number of objects in all of their categories. A chi-squared approximation to the distribution of A′ is developed and is shown to work well in a variety of situations. The relative powers of A′ and the ordinary X² test for association are dependent on the type of ‘agreement between the observers’ that is assumed. However a simulation for a fairly general type of agreement indicates that the X² test is more powerful. As the X² test is also much easier to apply, it would seem preferable in most situations.     

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.     

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.