Perceived duration as a function of pitch

It was demonstrated with 7 observers that the duration of a high frequency tone was perceived to be longer than the duration of a low frequency tone, even though the actual duration of the two tones was equal.     

Perceived roughness as a function of body locus

Twenty subjects made magnitude estimates of the roughness of grooved metallic surfaces applied to 10 body loci. To a first approximation, perceived roughness grew as a power function of groove width, in accordance with earlier studies. The exponents and intercepts (up-down position in log-log coordinates) of the power function turn out to depend strongly on body locus. The straight lines in log-log coordinates tend to diverge with groove width so that differences among body loci are especially pronounced at large groove widths. Sensitivity to roughness was greatest for the lips, fingers, and forearm, and least for the heel, back, and thigh. The rank order of the body loci in terms of roughness sensitivity closely parallels the rank order for punctate pressure sensitivity, as reported by von Frey in 1894, but apparently not for other measures of tactile sensitivity, such as vibration thresholds to various frequencies, two-point thresholds, and error of point localization.     

Perceived numerosity as a function of item size

In a sample of 48 subjects, there was a significant inverse relation between item size and estimation of numerosity. This result was shown to be consistent with Gestalt theory. According to this approach, the components of good figures appear more numerous, and smaller items produce better figures.     

Perceived relative distance on the ground affected by the selection of depth information

Our visual space does not appear to change when we scan or shift attention between locations. This appearance of stability implies that the depth information selection process is not crucial for constructing visual space. But we present evidence to the contrary. We focused on space perception in the intermediate distance, which depends on the integration of depth information on the ground. We propose a selection hypothesis that states that the integration process is influenced by where the depth information is selected. Specifically, the integration process inaccurately represents the ground when one samples depth information only from the far ground surface, instead of sequentially from the near to the far ground. To test this, observers matched the depth/length of a sagittal bar (test) to the width of a laterally oriented bar (reference) in three conditions in a full-cue environment that compelled the visual system to sample from different parts of the ground. These conditions had the lateral reference bar placed (1) adjacent to the test bar, (2) at the far ground, and (3) at the near ground. We found that the sagittal bar was perceived as shorter in conditions (1) and (2) than in Condition 3. This finding supports the selection hypothesis, since only Condition 3 led to more accurate ground surface integration/representation and less error in relative distance/depth perception. Also, we found that performances in all three conditions were similar in the dark, which has no depth information on the ground, indicating that the results cannot be attributed to asymmetric visual scanning but, rather, to differential information selection.     

Perceived velocity as a function of reference mark density

The effect on apparent visual speed of varying the density of stationary reference marks evenly distributed along the path of motion of a point of light was measured using tactile comparison motion. The sensitivity of the tactile method of measuring visual speed was supported by the finding that the tactile measures increased with each increase in physical speed of the point of light, other factors held constant. This procedure was applied in two experiments to visual displays in which the physical speed, extent of motion, and number and density of reference marks was varied. Only reference mark density, in addition to physical speed, was found to be a signficant (and robust) factor in determining perceived speed. The effect of reference mark density is explained in terms of the increasing contribution of relative motion cues to the perception of visual speed as a funciton of the average separation (or average adjacency) of the moving point from surrounding reference marks.     

Long-term retention as a function of word concreteness under conditions of free recall

Acquisition and long-term retention of concrete (C) and abstract (A) words were investigated under conditions of multiple-trial free recall. Both unmixed and mixed lists were used in original learning. Retention was tested either 1 rain or 1 week after attainment of the learning criterion. Acquisition was faster and retention was higher for C than for A words. These differences were more pronounced for mixed than for unmixed lists.     

Illusion reversal rate as a function of subjective depth

Undergraduate students (N = 48) served as subjects in a test of Gregory's theory of illusions. Twenty-four students made judgments about the subjective depth of three reversible illusions--Necker cube, Book, and Pyramid--under the conditions of complete versus incomplete illusions and illusions without depth cues versus with depth cues. An additional 24 subjects recorded the three illusion reversal rates under slightly altered conditions. Differences were found among the various illusions with respect to complete versus incomplete illusions, reversal rate, subjective judgments of depth, and certain correlation values. Support for Gregory's theory of illusion as displaced or misleading depth perception is offered by these results.     

Visual alleys as a function of instructions under informative and reduced conditions of viewing

Three experiments were designed to explore parallel and distance alleys as a function of instructions (apparent and objective) under three different distance-cue conditions. The main findings were that (1) the alleys for the apparent instructions were positioned closer to the median plane than those for the objective instructions, (2) in an indoor setting, the parallel and distance alleys were not different under either the apparent or the objective instructions, and (3) in an outdoor setting, the parallel alley lay inside the distance alley under both the apparent and the objective instructions. On the basis of comparison with some of the previous alley studies, it is suggested that exact control of instructions will not produce great discrepancy between the parallel and the distance alleys that were constructed indoors.