Are attentional dwell times inconsistent with serial visual search?

Duncan, Ward, and Shapiro (1994) estimated that attention must remain focused on an object for several hundred milliseconds before being shifted to another object, and they referred to this period as theattentional dwell time. An important implication of these long estimates of the dwell time for models of visual search is that the search process must not involve an item-by-item serial scanning mechanism. If it did, then searching through an array of items would require enormous amounts of time, which—based on data from visual search experiments—it does not. The present report, however, provides evidence that the long estimates of attentional dwell time were caused, at least in part, by the use of masked targets. Implications of these variable estimates of the attentional dwell time for models of visual search are discussed.     

Role of optical flow field asymmetry in the perception of heading during linear motion

During linear translation through a stationary environment, the pattern of optical flow generated on each retina is symmetrical when the head is aligned with the heading, but during lateral gaze the optical flow is asymmetric. We assessed whether human subjects could use the magnitude of this asymmetry to determine the direction of heading during passive translation through a 3-D environment. When allowed to move their heads in order to look in the direction of self-motion, subjects indicated their heading precisely and accurately. When the head was locked in alignment with the misaligned body, and gaze adjustments were not allowed, responses were quite precise, but showed a large bias which increased with increasing heading angle.     

A cognitive mediation theory of task goals and human performance

A theory is proposed to explain the linkages between individual task goals and performance. Two cognitive constructs are postulated to mediate between task goals and performance:performance expectancy and performance valence. It is asserted that an individual's task goal has a positive influence on performance expectancy and a negative influence on performance valence. Performance expectancy is proposed to have a positive influence on performance while performance valence is proposed to have a negative influence on performance. Task ability is hypothesized to influence performance both directly and indirectly through its influence on performance expectancy. A laboratory experiment was designed to test the causal model proposed by the theory. A path analysis on the data from this experiment provides strong support for the model, with performance expectancy, performance valence, and task ability predicting 63% of the variance in performance on the laboratory task.     

Philosophy of medicine and other humanities: Toward a wholistic view

A less analytic and more wholistic approach to philosophy, described as ‘best overall fit’ or ‘seeing how things all hang together,’ is defended in recent works by John Rawls and Richard Rorty and can usefully be applied to problems in philosophy of medicine. Looking at sickness and its impact upon the person as a central problem for philosophy of medicine, this approach discourages a search for necessary and sufficient conditions for being sick, and instead encourages a listing of “true and interesting observations” about sickness which reflect the convergence of a number of different viewpoints. Among the relevant viewpoints are other humanities disciplines besides philosophy and the social sciences. Literature, in particular, provides insights into the meaning and the uniqueness of episodes of sickness in a way that philosophers may otherwise fail to grasp.     

Interviewer evaluations of interviewee nonverbal behavior

Personnel representatives (N = 52) were shown one of four videotaped job interviews in which the verbal content of the 16-min interview was identical, but the interviewee's nonverbal behavior was manipulated. A “low nonverbal” interviewee was defined by minimal eye contact, low energy level, lack of affect and voice modulation, and a lack of speech fluency. The “high nonverbal” interviewee demonstrated the opposite behavior on each of these components. The subjects were asked to rate the videotaped candidates on dimensions previously identified as critical in influencing a job interviewer's decisions. Nonverbal behavior was found to have a significant effect on almost every rating made by subjects in this study. After reviewing the entire 16-min interview, 23 of the 26 subjects who saw the “high nonverbal” candidate would have invited him/her for a second interview. All 26 of the subjects who saw the “low nonverbal” candidate would not have recommended a second interview.     

Mid-career change in academia: The decision to become an administrator

This study explored the reasons why professors would leave their teaching/ research occupations to begin new careers as administrators. Valence-Instrumentality-Expectancy theory of occupational preference and choice was used as a framework to examine mid-career change among professors and department chairmen at a major university. Data showed that professors' intentions to change careers and become administrators could be explained by the theory. Analyses of job characteristics demonstrated that professors who want a mid-career change are primarily attracted by the power and formal authority vested in the administrative position, while professors who prefer to remain in their career paths do so because of the autonomy it offers.     

Reinforcement and punishment in a closed system

Children chose between toys freely and with various restrictive contingencies. Sometimes play with a preferred toy was contingent on play with a nonpreferred toy. Sometimes play with a nonpreferred toy was contingent on play with a preferred toy. Another toy (free toy) was always available during contingency sessions. Because toy playing occupied the entire session the response system was closed. When one response increased in duration others had to decrease. An analysis of closed-system responding revealed that the restrictions of the closed system together with the restrictions imposed by the contingencies forced subjects to alter the proportion of time devoted to the three responses. A geometrical model representing the closed system and an analytical method based on distance are presented to describe the data.     

Tables of d′ for variable-standard discrimination paradigms

Signal detection theory (SDT) allows a bias-free measure of sensitivity, d′, to be simply estimated from discrimination data when certain conditions are met. The computation is not straightforward, however, in several popular discrimination designs, such as two- and four-interval same-different designs and the ABX design. The present tables, derived from the SDT models of Macmillan, Kaplan, and Creelman (1977), make possible the estimation of d’ from these complex discrimination designs.