A Commodore 64-based interface system for the operant laboratory

A system of interfaces for the Commodore 64 (C-64) microcomputer for use in the operant laboratory is described. This system frees the experimenter from limitations on the number of I/O lines available on the user port of the C-64 and offers the control of operant chambers for a low cost. Subroutines in machine code to control the interfaces, offering millisecond timing of external events, are presented. A sample BASIC program demonstrates how the subroutines are called from BASIC to run a simple discrimination experiment.     

Monocular without stereopsis with and head movement

Random dots moving with various velocity gradients were presented to observers; the motion was yoked to head movement in one condition and to no head movement in another. In Experiment 1, 12 observers were shown motion gradients with sine, triangle, sawtooth, and square waveforms with amplitudes (equivalent disparities) of 12′ and 1° 53′. In Experiment 2, 48 observers were shown only the sinewave or square-wave gradient of 1° 53′ disparity either with or without head movement so that the observers’ expectation to see depth in one condition did not transfer to another. The main findings were: (1) with 12′ disparity, the head-movement condition produced perceived depth but almost no perceived motion, whereas the no-head-movement condition produced both perceived depth and perceived motion; (2) with 1° 53′ disparity, both conditions produced perceived depth and perceived motion; and (3) when the expectation to see depth was removed, the no-head-movement condition with the square-wave gradient produced no perceived depth, only motion. We suggest that monocular stereopsis with head movement can be achieved without perception of motion but monocular stereopsis without head movement requires perception of motion.     

Negative priming insame-different matching: Further evidence for a central locus of inhibition

Responses to recently ignored information may be slower or less accurate than responses to information not recently encountered. Such negative priming effects imply that the mechanism of selective attention operates on unattended, as well as attended, information. In the present experiment, subjects judged the second and fourth letters of five-letter strings (e.g., BABAB) as “same” or “different.” Responses were slower when a target letter was identical to the distractors presented in the immediately preceding trial. This effect did not depend on which response was required on the current or preceding trial. The results suggest that ignored information is functionally disconnected from the response system as a whole, rather than from a specific response.     

Tachistoscopic exposure of real objects for measurement of reaction time and movement time

In this paper, we describe an apparatus for measuring reaction times and movement times involved in reaching for real objects. Subjects view an object through a liquid crystal window, which serves as a shutter that can be made clear or opaque quickly (10 msec from opaque to clear, 30 msec from clear to opaque). The subject’s hand rests on a microswitch-equipped home key, and the object sits on a force-sensitive platform so that initiation of reach and time of contact with the object can be marked accurately. The apparatus interfaces with an IBM PC/AT through a digital I/O parallel port, so that reaction times and movement times are recorded automatically.     

Book reviews

The Word Speaks to the Faustian Man. Som Raj Gupta. Delhi, Motilal Banarsidass. 455+xvi pp., Rs. 500

A History of Indian Buddhism, From Sākyamuni to Early Mahāyāna. Hirakawa Akira, translated and edited by Paul Groner, 1990. Asian Studies at Hawaii, No. 36. Honolulu, HI, University of Hawaii Press. xix +402, £33.25

The Doctrine of the Upanisads and the Early Buddhism. Hermann Oldenberg, translated by Shridhar B. Shrotri, 1991. Delhi, Motilal Banarsidass. Rs. 225

Evil and the Mystics’ God: Towards a Mystical Theodicy. Michael Stoeber. London, Macmillan. x+225 pp., £40     

Affective responses to seeing oneself for the first time on unedited videotape

Despite the growing popularity of watching oneself on videotape, little systematic research has been conducted determine viewers' affective responses to video replay. This study addresses the question: what affective responses do women have when they view themselves for the first time on unedited videotape, in comparison to their responses when they view a peer or nature scenes on videotape? Affective responses were measured in three ways: self-report, physiological, and behavioral. Subjects who viewed themselves reported more negative feelings and anxiety, and smiled more frequently than subjects who watched another person or nature scenes on video. Subjects with high private self-consciousness had higher mean arterial blood pressures when viewing themselves than did subjects with low private self-consciousness. Overall, the implications for seeing oneself on video point to potential embarrassment but generally moderate effects.     

Willingness to Seek Help as a Function of Self-Disclosure and Problem Severity

In this study the authors examined the effects of problem severity, amount of self-disclosure, and self-disclosure flexibility on willingness to seek help for a problem. The participants were 101 midwestern university students enrolled in an introductory psychology course who had not had previous counseling experience. The participants completed the Jourard Self-Disclosure Questionnaire (SDQ), the Chelune Self-Disclosure Situations Survey (SDSS), and responded to questions after reading a scenario depicting a personal problem of either high or low severity. The results indicated that the factors that predicted the greatest amount of variance in willingness to seek help were the interaction of problem severity with willingness to self-disclose to a counselor, followed by problem severity; no gender differences were found. Implications for counseling and further research are discussed.