Cocaine tolerance: acute versus chronic effects as dependent upon fixed-ratio size.

The effects of cocaine on operant behavior were studied by examining fixed-ratio value as a factor in the development of tolerance. Pigeons pecked a response key under a three-component multiple schedule, with each bird being exposed to fixed-ratio values that were categorized as small, medium, or large. Administered acutely, cocaine (1.0 to 10.0 mg/kg) produced dose-related decreases in overall rate of responding. Responding maintained by the largest ratio was decreased by lower doses than those required to reduce rates of responding maintained by the other two ratio schedules. Following repeated daily administration of 5.6 mg/kg of cocaine, dose-effect functions (obtained from sessions during the chronic regimen by making substitutions for the daily dose) indicated tolerance under the smaller ratios, but no tolerance or less tolerance under the largest ratio. Thus, whether tolerance developed, and the degree to which it developed, depended on the ratio value. The results are partially consistent with the notion that tolerance to drug effects on schedule-controlled behavior will develop if drug administration initially reduces reinforcement frequency, but they indicate that reinforcement loss alone is not a sufficient condition for the generation of tolerance under such conditions. The findings suggest that amount of responding required for reinforcement, or "effort," may contribute to the development of tolerance to effects of cocaine.     

Reliability of verbal-manual interference

Considerable recent research has used unimanual finger tapping with concurrent vocalization to assess hemispheric lateralization for language. This study examined whether an index finger tapping task is a reliable measure in adults and whether the task demonstrates sex differences in hemispheric specialization for language. Thirty right-handed subjects, fifteen male and fifteen female, between the ages of 18 and 25 were tested. The task measured the differences in tapping rate for each hand between tapping with and without a concurrent verbal task. The task was completed once each day for 3 consecutive days to determine reliability. The tapping task was found to be a reliable measure. No significant differences were found between tapping scores of males and females.     

Interpolation across surface discontinuities in structure from motion Asad Satdpour

Interpolation across orientation discontinuities in simulated three-dimensional (3-D). surfaces was studied in three experiments with the use of structure-from-motion (SFM). displays. The displays depicted dots on two slanted planes with a region devoid of dots (a gap). between them. If extended through the gap at constant slope, the planes would meet at a dihedral edge. Subjects were required to place an SFM probe dot, located within the gap, on the perceived surface. Probe dot placements indicated that subjects perceived a smooth surface connecting the planes rather than a surface with a discontinuity. Probe dot placements varied with slope of the planes, density of the dots, and gap size, but not with orientation (horizontal or vertical). of the dihedral edge or of the axis of rotation. Smoothing was consistent with models of 2-D interpolation proposed by Ullman (1976). and Kellman and Shipley (1991). and with a model of 3-D interpolation proposed by Grimson (1981).     

Completing visual contours: the relationship between relatability and minimizing inflections.

Visual completion is a ubiquitous phenomenon: Human vision often constructs contours and surfaces in regions that have no sharp gradients in any image property. When does human vision interpolate a contour between a given pair of luminance-defined edges? Two different answers have been proposed: relatability and minimizing inflections. We state and prove a proposition that links these two proposals by showing that, under appropriate conditions, relatability is mathematically equivalent to the existence of a smooth curve with no inflection points that interpolates between the two edges. The proposition thus provides a set of necessary and sufficient conditions for two edges to be relatable. On the basis of these conditions, we suggest a way to extend the definition of relatability (1) to include the role of genericity, and (2) to extend the current all-or-none character of relatability to a graded measure that can track the gradedness in psychophysical data.     

Completing visual contours: The relationship between relatability and minimizing inflections

Visual completion is a ubiquitous phenomenon: Human vision often constructs contours and surfaces in regions that have no sharp gradients in any image property. When does human vision interpolate a contour between a given pair of luminance-defined edges? Two different answers have been proposed: relatability and minimizing inflections. We state and prove a proposition that links these two proposals by showing that, under appropriate conditions, relatability is mathematically equivalent to the existence of a smooth curve with no inflection points that interpolates between the two edges. The proposition thus provides a set of necessary and sufficient conditions for two edges to be relatable. On the basis of these conditions, we suggest a way to extend the definition of relatability (1) to include the role of genericity, and (2) to extend the current all-or-none character of relatability to a graded measure that can track the gradedness in psychophysical data.     

Constructing and representing visual objects

The objects we see are not given in the images at the eyes, but must be constructed by the human visual system. Indeed, damage to specific brain regions often leads to specific impairments of visual abilities (for example, the perception of shape, color or motion). Human vision constructs the various properties of visual objects, not independently of each other, but in a highly coordinated fashion. The construction of one visual property strongly influences the constructions of other properties. Visual shape is an important construction for successfully recognizing objects. There is growing consensus that human vision represents shapes in terms of component parts and their spatial relationships. These parts and their spatial relationships provide a powerful first index into one's visual memory of shapes.     

Children's vulnerability to stressful life events in mothers' eyes: Effects of gender and parental experiences

Although the professional literature indicates greater vulnerability to stress among boys than girls, research on stereotypes and gender typing in socialization offers indirect evidence of a contrary belief among parents. In order to assess sex differences in vulnerability directly, 80 Israeli middle-class mothers of elementary school children were asked to predict the difficulty that low- and high-stress life events would pose for child protagonists in eight vignettes. Sex of child was manipulated by gender label denotation. Results indicated that mothers of boys predicted greater child difficulties with stress than mothers of girls. They also predicted that boys would have more difficulty than girls, a sex difference that did not appear among mothers of girls. The results suggest that maternal perceptions of sex differences in vulnerability are influenced by observation of their own children under stress. Further, professional opinion and lay wisdom as to actual male vulnerability are not necessarily at loggerheads.     

Using HyperCard and Apple events in a network environment: Collecting data from simultaneous experimental sessions

HyperCard is a useful tool available to teachers and researchers who have access to Macintosh computers. Version 2.1 of HyperCard, in conjunction with the Macintosh Operating System 7, includes some significant new capabilities for users with multiple computers in a network, as is common in many teaching laboratories. This paper describes a HyperCard stack that allows users who wish to run HyperCard-based experiments on several computers simultaneously to conveniently retrieve experimental data from those remote computers onto one program, and to perform several other useful tasks in a computer network.     

The bidirectionality of judgments of synonymy

This article reports an experiment and some observations on synonymy between sentences. The rationale derives from experimental evidence for the existence of a nonverbal, abstract semantic memory, and for the mutual deducibility of two synonymous sentences. In the first phase of the experiment, subjects ranked interpretations of proverbs in terms of their semantic distance from their proverb bases. In the second phase, different groups of subjects ranked proverbs, including the phase 1 original proverbs and some foils, in terms of their semantic distance from the interpretations. The results indicate that two synonymous sentences tend to be given similar rankings, linearly related, and that subjects are highly consensual in their rankings. It is argued that a deep structure account cannot explain the results and that, furthermore, available linguistic and psychological theories of meaning are likewise insufficient. Synonymy is discussed in terms of an event or operation which serves to restrict interpretation.