Distance perception in photographic displays of natural settings

Distance perception of depicted objects was examined as a function of photographic perspective. 24 subjects viewed slides of outdoor scenes and directly estimated the distances to specified objects. Perspective was manipulated by photographing each scene with lenses of four different focal lengths: 48 mm, 28 mm, 24 mm, and 17 mm. Distance perception along the pictorial depth plane (z-axis) was systematically transformed by changing the photographic perspective: the shorter the focal length of the camera lens, the greater the perceived distance. Perceived distance between objects along the lateral plane (x-axis) was unaffected by changes in lens focal length.     

Pavlovian conditioning of sexual arousal: parametric and background manipulations

Recent studies have shown that a Pavlovian conditioned stimulus (CS) for unconsummated sexual arousal can increase the rate of copulation in the rat. This report includes five experiments examining the effects of parametric manipulations on the conditioned arousal response. Results show that between six and nine trials are necessary for reliable conditioning, but extinction is somewhat slower than acquisition. The function for the CS-US (unconditioned stimulus) interval is quadratic, with a minimum of several minutes required for effective conditioning. In the first three experiments, it appeared that background cues were conditioned as well as the designated CSs, and this was tested explicitly in the last two studies. In one, the effect of background cues was shown by training and testing in different situations; in the second, background cues were shown to be subject to latent inhibition. These results demonstrate the influence of Pavlovian learning in sexual behavior and help to provide the basis for an animal model of the acquisition of deviant sexual arousal in humans.     

Structural and operational capacities in integrative spatial ability

Four experiments were conducted to explore a distinction between structural capacity, the maximum number of informational units that can be temporarily stored, and operational capacity, the number of processing operations that can be executed while simultaneously preserving the products of earlier processing. The results, from a synthesis task requiring the integration of successively presented line segments into a composite stimulus, revealed that there were little or no age differences in structural capacity but large age differences favoring young adults in operational capacity. An attempt was also made to determine how much earlier information was available after each additional processing operation, but equivocal results precluded a definitive conclusion about the exact nature of the age differences in operational capacity.     

Expectancy Accessibility, Alcohol Expectancies, and Intentions to Consume Alcohol

Drug use tends to correlate more strongly with positive expectancies than with negative expectancies. The expectancy-accessibility model provides one explanation for this disparity. This model suggests that the association between positive expectancies of a drug's effects and intentions to use the drug are larger because positive expectancies are often more accessible in memory. Previous work supports the model for positive expectancies and intentions to use smokeless tobacco. Positive expectancies correlated significantly with intentions to use smokeless tobacco only when they were primed in memory. The current study attempted to extend these findings to alcohol consumption. Positive expectancies correlated significantly with intentions to drink when they were primed in memory, as the model predicts. Nevertheless, positive expectancies also correlated significantly with intentions when negative expectancies were primed. In addition, negative expectancies were not associated with intentions to drink, regardless of priming condition. These latter results are not consistent with the model. These findings suggest that the expectancy-accessibility model may be limited.     

Effects of stimulus variability on perception and representation of spoken words in memory

A series of experiments was conducted to investigate the effects of stimulus variability on the memory representations for spoken words. A serial recall task was used to study the effects of changes in speaking rate, talker variability, and overall amplitude on the initial encoding, rehearsal, and recall of lists of spoken words. Interstimulus interval (ISI) was manipulated to determine the time course and nature of processing. The results indicated that at short ISIs, variations in both talker and speaking rate imposed a processing cost that was reflected in poorer serial recall for the primacy portion of word lists. At longer ISIs, however, variation in talker characteristics resulted in improved recall in initial list positions, whereas variation in speaking rate had no effect on recall performance. Amplitude variability had no effect on serial recall across all ISIs. Taken together, these results suggest that encoding of stimulus dimensions such as talker characteristics, speaking rate, and overall amplitude may be the result of distinct perceptual operations. The effects of these sources of stimulus variability in speech are discussed with regard to perceptual saliency, processing demands, and memory representation for spoken words.     

Shifts in the perceived location of a blurred edge increase with contrast

Perceived brightness is nonlinearly related to luminance. Consequently, any mechanism operating on the (transformed) luminance profile of a blurred edge to detect its location should make errors, and the magnitude of these errors should increase with contrast. The perceived location of a blurred edge was measured at a range of contrasts and a range of blur space constants in a vernier alignment task. It was found that the perceived location of a blurred edge was affected by the contrast and the blur space constant of the edge. At low contrasts, the apparent location of the blurred edge was near the calculated location of the edge, assuming the linear transduction of luminance. At higher contrasts, the perceived location of a blurred edge was shifted toward the dark side of the edge, and the shift increased with contrast.     

Cardiac change scale: A brief, self-report research measure

The purpose of this study was to develop and evaluate a brief, self-report measure of the degree of perceived change resulting from cardiac illness. Life change has been widely recognized as stressful, but it is usually assessed with generic checklists of events which have been found wanting in terms of reliability and validity. The proposed measure was designed to assess life change in factors commonly reported to be important in recovery from cardiac illness. The Cardiac Change Scale was found to have very good internal consistency and acceptable test-retest reliability. The construct and criterion validity of the Cardiac Change Scale were supported.     

Shape constancy and theory of mind: is there a link?

In three experiments, children aged between 4 and 7 years viewed a circular disc oriented at a slant. The disc was made of luminous material and situated in a darkened chamber. Children of all ages exaggerated the circularity of the disc when they knew that the object was really a circle (the circle task), and the effect was greatest in the younger members of the sample. Crucially, however, a group of children in Experiment 3 who viewed an identical shape that they knew emanated from an actual ellipse did not exaggerate circularity. In the second experiment, children tackled three standard theory of mind tasks in addition to the circle task mentioned above. A significant correlation emerged (even with age partialed) between the extent of exaggeration made by those who knew that the shape was a circle and ability to pass the theory of mind tests. It seems knowledge of reality contaminates judgements of appearance in the circle task. This might be the same bias that features in realist errors in theory of mind tasks.     

Delay or probability discounting in a model of impulsive behavior: effect of alcohol

Little is known about the acute effects of drugs of abuse on impulsivity and self-control. In this study, impulsivity was assessed in humans using a computer task that measured delay and probability discounting. Discounting describes how much the value of a reward (or punisher) is decreased when its occurrence is either delayed or uncertain. Twenty-four healthy adult volunteers ingested a moderate dose of ethanol (0.5 or 0.8 g/kg ethanol: n = 12 at each dose) or placebo before completing the discounting task. In the task the participants were given a series of choices between a small, immediate, certain amount of money and $10 that was either delayed (0, 2, 30, 180, or 365 days) or probabilistic (i.e., certainty of receipt was 1.0, .9, .75, .5, or .25). The point at which each individual was indifferent between the smaller immediate or certain reward and the $10 delayed or probabilistic reward was identified using an adjusting-amount procedure. The results indicated that (a) delay and probability discounting were well described by a hyperbolic function; (b) delay and probability discounting were positively correlated within subjects; (c) delay and probability discounting were moderately correlated with personality measures of impulsivity; and (d) alcohol had no effect on discounting.