Art produced by a patient with Parkinson's disease

Artists with neurological diseases sometimes produce remarkably appealing art. Here we present the art of a patient with Parkinson's disease, who demonstrated remarkable creativity and productivity well into the course of his disease. Despite his manifest motor impairments, he produced paintings and drawings with fluid sinuous movements. He also became preoccupied with his art in an unprecedented way, raising the possibility that his disease and medications were contributing to his creative drive.     

Fakability of a commercially produced pre-employment integrity test

Three groups of male inmates were given the PSC Survey ADT, a commercially available integrity test, under differing instructional conditions. Subjects told to fake good were able to provide more favorable test profiles than those who were told to respond truthfully or who were given no specific response set to follow. However, no differences were observed among groups on the Drinking and Drugs subscale. Using only recommended cut scores as criteria, subjects in the fake good condition would have been hired in greater numbers than subjects in the other two conditions. Practical implications of this study include the use of social desirability scales along with integrity tests, and the avoidance of inducing inappropriate response sets by strictly adhering to test instructions.This study was supported by a grant from Auburn University at Montgomery.We gratefully acknowledge the support and assistance of Warden Leoneal Davis and Dr. Paul Van Wyk of the Bullock County Correctional Facility and the Alabama Department of Corrections in conducting this study.     

A microgenetic model of paragrammatisms produced by a schizophrenic speaker

A series of papers appearing in Brain and Language ask whether schizophrenic language irregularities can be understood in linguistic terms. This literature is reviewed and the contrary positions of different authors are highlighted. The clinical presentation of a schizophrenic male is described. In a single interview he produced a set of paragrammatical errors which are noteworthy insofar as they indicate sustained epochs of diminished expressivity. In this sense, they differ from schizophasic deviance, which is described by Lecours and Vanier-Clement (Brain and Language, 3, 516-565, 1976) as an enhanced expressivity cooccurring with intact language competence. They are also partially decodable, which distinguishes them from the schizophrenic segments discussed by Chaika. Analyses of the paragrammatisms indicate disruptions at three discrete representational levels. One involves the formation of abstract speaker intentions, while the second organizes syntagms into some serial form, and the third level takes content words belonging to a particular syntagm and positions them in a syntactic frame. A microgenic model of these representational planes is proposed that is based on the theoretical perspective of Brown, as well as Garrett's investigations of normal speech errors. The model is justified insofar as the paragrammatisms indicate "linguistic regressions" back to more "thought-like" linguistic representations. Moreover, a recapitulation of specific linguistic mappings is demonstrated to occur between processing levels. This microgenetic model represents an extension of previous work in aphasiology insofar as it targets combinatorial rather than selectional processes as primary planes of disruption.     

Attack produced by intermittent reinforcement of a concurrent operant response

Squirrel monkeys pressed a lever to produce food on several fixed-ratio schedules; they could also bite a rubber hose. Biting attack occurred during the postreinforcement pause and in early portions of the ratio response run. Also, biting attacks increased after transitions to higher values of the fixed-ratio requirement and in extinction. The results show that extinction-induced aggression effects occur in primates.     

Kanizsa's shrinkage illusion produced by a misapplied 3-D corrective mechanism

In order to include the monocular areas from the left and the right eye in the cyclopean view, the visual system displaces the occluded elements which would result in a horizontal elongation of the shape but does not occur thanks to a correction mechanism which preserves the shape. We hypothesised that this mechanism causes Kanizsa's amodal shrinkage illusion (the apparent elongation of a partially occluded square) when it is incorrectly applied by the visual system to a two-dimensional stimulus. Four experiments tested this hypothesis: (i) one-eyed observers were less susceptible to the illusion than people with normal binocular vision because, for them, the correction for shape is unnecessary; (ii) the illusion was stronger with binocular than with monocular vision since binocularity induces the visual system to correct for the shape distortion; (iii) the illusion diminished when the stimulus was rotated 90 degrees given that displacement and compression are not required for vertical occlusion; (iv) the magnitude of the illusion was a function of the width of the occluder because, as previous research has shown, the edges of a partially occluded square are less displaced the farther they are from the edges of the occluder. The data from the four experiments support our hypothesis even though no condition was able to eliminate the illusion; other possible causes are discussed.     

Wear behaviour of a gradient surface produced by a punching process in a Cu-30 Ni alloy

The grain size variation in a gradient surface produced by a punching and recovery process on a Cu-30Ni alloy has been observed by atomic force microscopy. The friction characteristics of the gradient surface in a 3.5 wt% NaCl solution were investigated using a micro-indenter probe, a pin-on-disc type tribometer, a strain sensor and an optical microscope. The results showed that the hardness and grain size can be well represented by the Hall–Petch relationship when the gain size is more than 30?nm. The wear rate, friction coefficient and adhesive force all increase depth below the surface. These variations are attributed to a gradual increasing grain size with depth. The morphologies of the worn track were also studied to understand further the corrosive wear behaviour of gradient surfaces.     

Behavioral contrast produced by a signaled decrease in local rate of reinforcement

Pigeons' key pecking in the presence of one stimulus (S1) was reinforced according to a response-dependent variable-interval schedule. Pecking rate during S1 increased (behavioral contrast) when a second stimulus (S2) [associated with either a response-dependent fixed-interval schedule (Experiment I) or a response-independent reinforcement schedule in which reinforcement availability was signaled by visual (Experiment II) or temporal (Experiment III) stimuli] alternated with S1. These experiments suggest that a discriminable, signaled decrease in local reinforcement rate during S2 is an antecedent of the behavioral contrast response rate increases during S1.     

A three-dimensional motion aftereffect produced by prolonged adaptation to a rotation simulation

After adaptation to a perspective simulation of a square plane rotating in depth, an ambiguous rotation simulation (ie one containing no perspective information) appears to rotate in the direction opposite that of adaptation. The strength of this three-dimensional motion aftereffect (MAE) is proportional to the amount of perspective available in the adaptation display and, in the dark, decays to about 75% of its initial strength within about 546 s. The nature of the testing situation and a control experiment suggest that the three-dimensional MAE is not caused by retinal adaptation of two-dimensional directionally selective mechanisms.     

Magnitudes of score differences produced within sessions in a cooperative exchange procedure

Interest centered on maximal score differences produced within sessions during two-party exchange. Subjects chose between earning money independently or through potentially higher-paying exchange. In the exchange option, only one person could produce points for the other on a trial. Because each exchange response (“give”) required the giver to forego earning points independently, the larger the score difference produced (i.e., the further ahead in earnings the other person was put), the greater the reduction in the giver's earnings if the other person did not reciprocate. Results showed that scores were usually equal at the end of each session, and that subjects maintained close equality of scores throughout each session. When a response-cost contingency that punished the alternation of giving was introduced, however, large within-session score differences developed. These large differences continued to be produced after the response-cost contingency was removed. Finally, when subjects were told that the session could end at any moment, score differences were sharply reduced, indicating that production of score differences remained under the control of discriminative stimuli associated with the likelihood of reciprocation. The study suggests that with appropriate procedures, an experimental analysis of behavioral phenomena associated with the concept of “trust” may be possible.     

Focal changes in cerebral blood flow produced by a test of right-left discrimination

A sensorimotor control activation task was used to isolate the focal cerebral blood flow changes resulting from the visual and cognitive processing of a right-left discrimination task. Eleven normal right-handed males participated. The sensorimotor control task produced significant bilateral increases in flow in most cortical channels. Significant bilateral parieto-occipital activation was found for the right-left discrimination task over and above the flow changes produced by the sensorimotor control task. The left occipital flow increase resulting from the right-left discrimination task was found to be negatively related to task performance. An inverse relationship was also found between WAIS Performance IQ and the blood flow change in the left parietal channel. These results suggest areas for further testing concerning potential individual differences in cognitive processing during the performance of a right-left discrimination task.     

Apparent movement and change in perceived location of a simulus produced by a change in accommodative vergence

Using a psychophysical method of adjustment, 175 Ss, ranging in age from 3 to 20 years, made four adjustments each of a luminous line to subjective vertical, horizontal, and 45-deg tilts in the dark. There were no significant differences in mean errors of adjustment to the vertical and horizontal over the ages tested. There were significant differences in intra-S variability of adjustment to the horizontal and vertical, with the greatest improvement occurring before age 10. Older children and adults produced significantly larger mean errors of adjustment to the 45-deg tilt than did the younger children; but the variability of settings by younger children was very high, indicating that they did not discriminate the 45-deg tilt more accurately than the older groups. The intra-S variability at all ages showed that adjustment was more accurate to the horizontal and vertical than to the 45-deg tilt.     

Changes in threshold level produced by a signal preceding or following the threshold stimulus

In a previous experiment (Howarth and Treisman, 1958) it was shown that when a warning preceded a stimulus by a fixed interval, the threshold level for the stimulus was higher the longer the fixed interval. A model of this effect was proposed, assuming that the threshold criterion adopted by the subject at any moment was modified by his estimate of the probability of a stimulus at that moment.

Three predictions are derived and tested. It is found that: the standard deviation of the response is constant despite the shifts in threshold induced; the threshold continues to fall as the interval from warning to stimulus is decreased to zero, with the lowest threshold when the warning signal and the stimulus are simultaneous; and that a warning signal following the stimulus by an interval of less than 0 5 to 1 sec. also lowers the threshold.     

Determination of CIE chromaticity coordinates of colored lights produced by a projection color mixer

A procedure for measuring the CIE chromaticity coordinates which avoids some of the problems encountered with the method reported by Murch (1972) is described.     

Colored aftereffects produced with moving edges

Colored aftereffects that lasted as long as 6 weeks were produced with moving patterns of parallel black and white stripes or with black and white spirals. During adaptation, the patterns moved periodically in opposite directions, each direction paired with one illuminant, red or green. When the moving patterns were later viewed in white light, S saw the red and green colors, but they were related in the opposite way to the direction of motion. The red and green aftereffects were also produced by other pairs of illuminants, red and white, white and green, reddish-yellow and white, and white and greenish-yellow. The aftereffects did not occur unless, during adaptation, the stripes moved in both directions, each direction paired with a different color. The aftereffect was elicited by stripe motion over the retina—it was seen when the eye swept over a pattern of stationary stripes. The aftereffect desaturated when the retinal orientation of the stripes was changed from the adaptation orientation. Saturation was increased by longer exposure and slower speed during adaptation and by faster speed and a more rapid rate of altemation during the test. The luminance of the adaptation light seemed to have little effect. The aftereffect did not transfer from one eye to the other, and it did not change retinal locus, as was shown when clear images of a colored square that lasted several days were produced with a spiral. S ftxated the spiral’s center. The spiral rotated altemately in opposite directions. A red square with a green surround was projected on the center of the spiral when it rotated in one direction; a green square with a red surround was used when it rotated in the other direction. Following 50 min of adaptation, colored images of the squares were seen when the center of the spiral was ftxated and the direction of     

Perceptual grouping produced by line figures

Two experiments, one with 2 and one with 3-line figures, studied the relative effectiveness of differences in orientation and shape in producing grouping by Similarity. The results showed that changes in shape or orientation which leave the component lines of the figures vertical and horizontal do not facilitate grouping as readily as changes which alter the direction of the component lines to 45° and 135°. These results corroborate and extend the findings of Beck (l966a, 1966b) and are discussed in relation to the problem of specifying the properties of line figures that produce grouping by similarity.