ELOPTA: A novel microcontroller-based operant device

Operant devices have been used for many years in animal behavior research, yet such devices a regenerally highly specialized and quite expensive. Although commercial models are somewhat adaptable and resilient, they are also extremely expensive and are controlled by difficult to learn proprietary software. As an alternative to commercial devices, we have designed and produced a fully functional, programmable operant device, using a PICmicro microcontroller (Microchip Technology, Inc.). The electronic operant testing apparatus (ELOPTA) is designed to deliver food when a study animal, in this case a bird, successfully depresses the correct sequence of illuminated keys. The device logs each keypress and can detect and log whenever a test animal i spositioned at the device. Data can be easily transferred to a computer and imported into any statistical analysis software. At about 3% the cost of a commercial device, ELOPTA will advance behavioral sciences, including behavioral ecology, animal learning and cognition, and ethology.     

Generating variables with arbitrary properties

There are occasions in psychological research where it is desirable to have available sets of variables with arbitrary intercorrelations. A quite simple procedure is described for generating pairs of such variables.     

Interpolation in structure from motion.

We investigated surface interpolation in displays of structure from motion (SFM). To do so, we introduced a new method for measuring surface perception in dynamic displays--the SFM probe. An SFM probe is a dot that moves rigidly with the dots on a simulated surface, and whose distance from that surface can be adjusted with a joystick or similar control. The displays we studied were random-dot cylinders containing a vertical strip devoid of feature points (the gap). Subjects adjusted an SFM probe, presented in the gap, until the probe dot appeared to be on the surface. Variability in probe-dot placement decreased with increasing texture density on the cylinder and increased with increasing gap width. Subjects showed a consistent bias to place the probe dot outside the cylinder. This bias increased with increasing texture density for the SFM displays. (The opposite bias was found in a static two-dimensional interpolation task with an arc whose curvature matched that of the cylinder: Subjects placed the probe dot inside the arc.) This outside bias is inconsistent with several theoretical approaches to surface interpolation.     

Reading and visual memory: remembering scenes that were never seen.

In Experiment 1 (N = 16), under conditions of high memory load (60 pictures and 50 paragraphs) and a 1-week retention interval, undergraduate subjects reported their memory for photographs of scenes (cued recall and free-recall tasks). Subjects frequently reported memory for photographs that they had actually never seen, but had read about in a brief paragraph. In Experiment 2 (N = 40), the same pattern of results was obtained with immediate testing. Experiment 2 also demonstrated that the likelihood of subjects falsely attributing scene memory (based on reading) to actually having viewed a photograph was reduced when metacognitive awareness of imaging during reading was made salient. Awareness of image creation was induced by requiring subjects to rate the paragraphs with respect to imagery vividness. Although other measures of memory remained the same, subjects in the induced-imagery condition made 50% fewer confusion errors than subjects who read the paragraphs without imagery instructions. The results are discussed in the context of Johnson and Raye's (1981) reality monitoring model.     

Psychological and sexual functioning among outpatient sexual offenders against children: A Minnesota Multiphasic Personality Inventory (MMPI) cluster analytic study

Multivariate clustering procedures were used to identify homogeneous subgroups of outpatient sex offenders against children (n=110)on the basis of the Minnesota Multiphasic Personality Inventory (MMPI). Results indicated a five-subgroup solution. Two within-normal-limits and two clinically elevated profile subgroups replicated subtypes found in previous cluster analytic studies of child sex offenders. The fifth subgroup appeared similar in MMPI profile pattern and elevation to a previously identified subtype of rapists. Discriminant analyses showed that subgroups differed along dimensions of cognitive disturbance and sexual functioning. Furthermore, levels of psychopathology corresponded with levels of sexual pathology. Results are discussed with reference to previous MMPI cluster analytic studies of sex offenders and theories of sexual aggression.Portions of this paper were presented at the meeting of the Midwestern Psychological Association, 1992, Chicago, Illinois.     

An apparatus for the assessment of prepulse inhibition in the frog

A system for studying prepulse inhibition in the leopard frog is described herein. It entails a modification of an apparatus developed almost a century ago, by Yerkes, for his investigations of hearing in the frog. With the present system, a frog is restrained in a cylindrical vessel (constructed from a 35-mm film canister), and the canister is positioned in the apparatus so that the animal’s legs hang downward. A miniature solenoid is used to deliver a startle eliciting tap to the frog’s head, and the resulting leg movement is detected by an optical densitometer. In addition to providing a convenient way to restrain frogs, our system enabled us to, in part, replicate Yerkes’s basic procedures with these subjects. As did Yerkes, we found that an acoustic signal just prior to a tap on a frog’s head inhibits the leg movement that would otherwise be elicited.     

A Demonstration of Conjoint Analysis for Organizational Research

The purpose of this study was to demonstrate the potential usefulness of conjoint analysis for organizational research, as evidenced in estimating the compensating wage differential of the four-day workweek. Five hundred and seventeen employees of an insurance company on the four-day workweek rated their preferences for increments and decrements in compensation and vacation time on both a four-day and five-day workweek. The data were analysed via conjoint analysis. The results revealed the four-day workweek schedule had a positive compensating wage differential of approximately US$1161, or about 6% of the sample's annual salary. The findings were discussed in terms of the prospects of using conjoint analysis for organizational research, including means of data collection, stimulus construction, parameter estimation methods, reliability, validity and computer-interactive systems.     

Race,gender, and the response to stress: Autoworkers' vulnerability to long-term unemployment

A three-wave panel study of auto plant closings focused on the mental health effects of unemployment on blue-collar workers. This paper explores how the impact of long-term unemployment varies across race and gender. We also examine whether other demographic factors can themselves modify the impactsof race and gender. Dependent variables include two measures of distress and two drinking measures. Results showed that the effect of long-term unemployment on distress and drinking was more severe among less educated workers, and responses of blacks were especially sensitive to level of education. In addition, men showed a greater association of long-term unemployment with depression (and to some extent anxiety) than did women. Marriage affected the responses of men but not of women, and of whites but not of blacks. Explanatory variables—the worker's experiences of financial hardship, other negative life events, and lack of a confidant—largely accounted for male-female differences. We conclude by discussing theoretical implications of these effects and address the limitations of the traditional term “vulnerability” in describing them. A prior version of this paper was presented at the North Central Sociological Association meeting in Dearborn, Michigan, April 25, 1991. Funds for the research were provided by the Michigan Health Care Research and Education Foundation and by the International Union-UAW. We are especially grateful to the men and women of the UAW, whose experiences and views form this investigation. We thank Kiseon Chung, Scott McKearney, David Rauma, and the anonymous reviewers for their comments on earlier drafts.     

The role of visual attention in saccadic eye movements

The relationship between saccadic eye movements and covert orienting of visual spatial attention was investigated in two experiments. In the first experiment, subjects were required to make a saccade to a specified location while also detecting a visual target presented just prior to the eye movement. Detection accuracy was highest when the location of the target coincided with the location of the saccade, suggesting that subjects use spatial attention in the programming and/or execution of saccadic eye movements. In the second experiment, subjects were explicitly directed to attend to a particular location and to make a saccade to the same location or to a different one. Superior target detection occurred at the saccade location regardless of attention instructions. This finding shows that subjects cannot move their eyes to one location and attend to a different one. The results of these experiments suggest that visuospatial attention is an important mechanism in generating voluntary saccadic eye movements.