High-speed 2-D and 3-D animation on the IBM PC/XT/AT

This article describes programs for performing high-speed two-dimensional (2-D) and three-dimensional (3-D) animation on IBM PC/XT/AT and compatible machines that use the color/graphics adapter. Machine language routines interfaced through BASIC allow the user to store screen images in memory as they are created by user software and then to display the sequence of images at rates of up to 60 frames per second. A BASICA 3-D graphics editor that can be used with the routines permits the user to create wire-frame objects and to move them about rigidly in conceptual space while projecting them onto the display screen. These programs should find application in the study of visual perception and cognition.     

Televised Models of Female Achievement Revisited: Some Progress

In a previous study which analyzed the content of a sample of 1972 primetime television programming, Manes and Melnyk (1974) concluded that television portrayed employment and marriage as incompatible life-styles for women. The present study applied the same content analysis procedures to a sample of 1978 prime-time television programming. Results indicated that female characters employed outside the home were significantly less likely to be married than were employed male characters ( p <.001), a finding which replicated the result obtained previously. In contrast to the 1972 results, however, analyses of the 1978 data revealed that employed married women were not significantly less likely than either their male counterparts or unemployed housewives to be depicted as successfully married.     

Changes in Behaviour and Body Weight Following a Single or Double Social Defeat in Rats

In a series of experiments, the consequences of a single and double social conflict on various behaviours and body weight in rats were studied. Animals were subjected to social defeat by placing them into the territory of an aggressive male conspecific for one hour, either once, or twice at the same time on two consecutive days. To assess the consequences of social defeat, three experiments were performed with independent groups of rats. In the first experiment, an open field test was performed two days after the last conflict. Locomotor activity was strongly reduced after social defeat. There were no differences between the single and double defeat group. To assess the effects of social defeat on subsequent social behaviour, a second experiment was performed in which experimental animals were confronted with an unfamiliar non-aggressive rat two days after a single or double conflict. Social defeat resulted in a reduction of social contact with the unfamiliar conspecific. There was no difference between the single and double conflict group. In the third experiment, the effects of social conflict on food intake, body weight and saccharine preference were measured. Food intake was not affected after a single conflict, but in the double conflict group food intake was decreased for several days. Body weight gain was decreased after both single and double social defeat. The decrease was stronger in the double conflict group. Water intake and saccharine preference were not significantly affected. This study revealed that social defeat in rats causes pronounced changes in various behaviours and body weight. Different aspects of behaviour are differentially affected by defeat with respect to the magnitude and time course of the changes induced. Moreover, different behavioural parameters are differentially sensitive to repetition of the stressor.     

Assessing auditory distance perception using perceptually directed action

Three experiments investigated auditory distance perception under natural listening conditions in a large open field. Targets varied in egocentric distance from 3 to 16 m. By presenting visual targets at these same locations on other trials, we were able to compare visual and auditory distance perception under similar circumstances. In some experimental conditions, observers made verbal reports of target distance. In others, observers viewed or listened to the target and then, without further perceptual information about the target, attempted to face the target, walk directly to it, or walk along a two-segment indirect path to it. The primary results were these. First, the verbal and walking responses were largely concordant, with the walking responses exhibiting less between-observer variability. Second, different motoric responses provided consistent estimates of the perceived target locations and, therefore, of the initially perceived distances. Third, under circumstances for which visual targets were perceived more or less correctly in distance using the more precise walking response, auditory targets were generally perceived with considerable systematic error. In particular, the perceived locations of the auditory targets varied only about half as much in distance as did the physical targets; in addition, there was a tendency to underestimate target distance, except for the closest targets.     

Counterexample to the hypothesis of functional similarity between tactile and visual pattern perception

In earlier work, the author has demonstrated that tactile pattern perception and visual pattern perception exhibit many parallels when the effective spatial resolution of vision is reduced to that of touch, thus supporting the hypothesis that the two pattern senses are functionally similar when matched in spatial bandwidth. The present experiments demonstrate a clear counter-example to this hypothesis of functional similarity. Specifically, it was found that the lateral masking effect of a surround on tactile character recognition increases when the surround changes in composition from solid lines to dots, whereas for vision, recognition performance goes in the opposite direction. This finding necessitates some modification of the model of character recognition proposed by the author (Loornis, 1990) as it applies to the sensing of raised tactile patterns. One possible modification would be to incorporate, as the initial stage of pattern transformation, the continuum mechanics model for the skin that was developed by Phillips and Johnson (1981b).     

Necessity,The A Priori,And The Standard Meter

This article critically examines SaulKripke's (1972) argument for the separability ofnecessary truths from truths known a priori,focusing on his criticism of the standard meter casepresented by Wittgenstein (1968). It attempts to showthat Kripke's argument is unworkable on any of severalreadings. Wittgenstein's own broadly conventionalistaccount of necessary truth is then considered in thelight of the standard meter example.     

Sensitivity to shifts of a point stimulus: An instance of tactile hyperacuity

The sensitivity of the tactile sense to shifts in the position of a point stimulus was determined at four body loci: the index finger, forehead, belly, and back. Water-jet stimulation was used, a method which allows frictionless travel of a point stimulus over the skin. Three subjects were tested by means of the method of forced choice, with the task being to say whether the stimulus moved to the right or to the left. The shift threshold was defined as that shift excursion which gave rise to 75% correct responding. The basic finding was that shift thresholds were on the order of 10 to 30 times smaller than the corresponding two-point limens obtained by Weinstein (1968) for the same body loci. These unexpectedly small shift thresholds indicate an exquisite sensitivity of the cutaneous sense to rapid changes in position of a point stimulus. A physiological model is presented which accounts for the difference between localization and spatial resolution. nt]mis|This research was supported by Department of Health~ Education, and Welfare Grant 14-P-SS282/9 from the Social and Rehabilitation Services, NIH Research Grant R01-EY-00686 from the National Eye Institute, and the Smith-Kettlewell Eye Research Foundation.     

Utilizing Need for Cognition and Perceived Self‐Efficacy to Predict Academic Performance1

A study was conducted to determine whether academic performance could be predicted on the bases of the constructs need for cognition (NFC) and academic self‐efficacy. Two hypotheses were generated: Positive correlations will be found between academic self‐efficacy, NFC, and grade point average (GPA); and efficacy and NFC will serve as significant predictors of GPA. The path mediation technique recommended by Baron & Kenny (1986) for testing mediated relationships was also performed in order to assess the causal direction of the NFC and academic self‐efficacy variables. Participants were 138 undergraduate students. The first hypothesis was generally supported in that significant correlations were found between NFC, efficacy beliefs, and GPA. In support of the second hypothesis, path analysis revealed that NFC and academic self‐efficacy were significant predictors of GPA. Furthermore, the NFC‐GPA relationship was shown to be mediated by efficacy beliefs.