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.     

Intrahemispheric sex differences in the functional representation of language and praxic functions in normal individuals

Kimura (1980, The Behavioral and Brain Sciences, 3, 240-241; 1983, Canadian Journal of Psychology, 37, 19-35; 1987, Canadian Psychology, 28, 133-147) recently proposed that there are intrahemispheric sex differences in the organization of particular language and praxic functions such that in females these functions are more focally represented. This hypothesis, as well as supporting data, was derived from research with brain-injured subjects. The purpose of the present study was to test the utility of using dual-task methodology for investigating sex-related variation in intrahemispheric functional organization in normal individuals. Women were found to show greater interference than men on concurrent tasks of language and right-hand finger tapping. In support of Kimura's model, the present findings yielded evidence suggestive of intrahemispheric sex differences in the "functional distance" between language and praxic functions within the left hemisphere of normal individuals.     

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.     

Thyroid hormones,psychophysiological reactivity,and anxiety

Thirty-eight adults were assigned to three groups: posttreatment hyperthyroid (n=13), low euthyroid (n=12), and high euthyroid (n=13). Physiological and subjective responses to three anxiety-induction procedures—public speaking, personally distressing imagery, and threat of shock—were compared across groups. Although there were differences across stressors for physiological and subjective measures, group differences were not detected. Results are discussed with regard to the risk for residual anxiety following treatment for hyperthyroidism and the possible influence of thyroid function on the etiology or maintenance of anxiety.