The case for praxics

Since the early 1900s a variety of names has been proposed for the scientific study of behavior, but none has come into general use. "Praxics," a recent entry, is defensible on several grounds. "Behaviorism," on the other hand, is the name of a school of philosophy. Though praxics has roots in behaviorism, the term "behaviorism" should not be applied to praxics. Confusion between the science and the philosophy has retarded the growth of the science immeasurably. Its growth has also been impeded by its association with psychology, which is still primarily the study of mind. Efforts are underway to establish praxics as an independent field.     

Adaptation to uniocular image magnification: Is the underlying shift proprioceptive?

Ss wore a 4% overall size lens (OSL) before one eye while they engaged in 20 min of binocular exploration of a typical indoor environment. Tests before and after the exposure period were conducted to determine whether or not OSL exposure leads to shifts in depth judgments based on binocular disparity. No significant shifts were observed. These results were applied to an evaluation of two contrasting hypotheses that have been proposed to explain adaptation to meridional size lens (MSL).     

Differential specialization of the cerebral hemispheres for the perception of sameness and difference

The Johns Hopkins University, Baltimore, Maryland 21218 Pairs of letters were presented 4 deg left or right of fixation, and Ss were asked to indicate as quickly as possible whether the letters in a pair were the same or different. Reaction times for “different” responses were faster when stimuli were in the left visual field than in the right, but reaction times for “same” responses were faster when stimuli were in the right visual field than in the left. These results may indicate that the right hemisphere is better specialized for difference detection, while the left hemisphere is better specialized for sameness detection.     

Size and distance judgments under reduced conditions of viewing

Magnitude estimations of the size and distance of a variable relative to a standard were obtained in the absence of distance cues. Estimates were provided by different groups under three conditions: (a) physical size and distance variant, visual angle of the variable constant and equal to the standard, (b) physical size constant, physical distance and visual angle of variable changing, and (c) physical distance constant, physical size and visual angle of the variable changing. The results in both experiments were very similar. In each case both size and distance estimates conformed to relative visual angle. The results are applied to an analysis of size-matches that are obtained when distance cues are eliminated.     

In search of depth

Four experiments designed to investigate a visual search task are reported. In each experiment, subjects searched for either a two-dimensional shape rotated in depth among frontal-parallel distractors or a frontal-parallel shape among distractors that were rotated in depth. The principal independent variable was search-set size. In addition, over the four experiments, a variety of spatial arrangements and two axes of rotation in depth were sampled. The chief aim of the experiments was to adduce evidence bearing on the attentional demands of searching for depth. The slopes of the reaction-time (RT) functions were taken as diagnostic. Experiments 1–3 exhibited positive slopes for the RT-set-size function. These slopes appear to be due to a conscious adoption of a serial search strategy by the subjects. When this tendency was suppressed by the procedures of Experiment 4, the slope of the RT-set-size functions did not differ significantly from zero. We conclude that, in agreement with the findings of other studies, slant-in-depth can be detected preattentively.     

The representational framework in perceptual theory

The representational stance in perceptual theory is described and its proper domain of application is examined. A decision rule for invoking representation is proposed but, although the rule is principled, its implementation is problematic. Despite the widespread appeaLof therepresentational stance, detailed working out of the position within perceptual theory is still needed.