Distance adaptation depends upon plasticity in the oculomotor control system

Maintaining binocular fixation on a target at 20 cm in the absence of secondary cues to distance produced changes in apparent distance and lateral phoria. Positive lenses of 0, .5, 2.0, 3.5, and 5.0 spherical diopters (SD) were used to manipulate the level of accommodative convergence in force during the period of maintained fixation. An inverse relationship was found between the stimulus to accommodation and the magnitude of the induced esophoria, the phoria being linearly related to an increase in apparent distance. The distance aftereffect obtained in the condition with the lowest net accommodative stimulus li.e., 0 D) equaled that typically produced by base-out prism adaptation with full secondary cues to distance available. In a second experiment, subjects walked through a well-lit hallway while viewing through a pair of 5h base-out prisms. It was shown that increasing the stimulus to accommodation by adding negative lenses of 0, 1.5, 3.5, and 5.5 SD reduced the adaptive change in apparent distance, as well as the change in phoria produced by the conventional base-out prism adaptation paradigm. It was concluded that a change in the resting tonus of the disparity vergence system underlies such adaptation, rather than recalibration of the oculomotor cues to distance. Monocular exposure data indicated that a small change in the tonus control for the accommodative system may be present as well.     

Construct validity of perceptual style: Role of stimulus size in the embedded-figures test and the rod-and-frame test

Three experiments were performed in order to test the construct validity of perceptual field dependence (FD) and field independence (FI). In Experiment 1, performance of subjects on two sizes of Form A of Witkin’s Embedded Figures Test (EFT) with a size-ratio of 1 to 4 was compared. The size of the standard EFT was taken as unity. A nonsignificant size effect was found for all subjects as a group, and a significant rank correlation was found between performances on the two sizes of the EFT. Furthermore, the performance of field-dependent subjects (as defined by performance on the standard EFT) and field-independent subjects did not interact significantly with the size factor. In Experiment 2, the physical size of the EFT changed from 1 to 8. A nonsignificant, overall size effect was again found, but the EFT performance of fielddependent and field-independent subjects interacted significantly with the size factor. In Experiment 3, the performance of subjects on two sizes of the EFT (i.e., 1 to 8) and two sizes of the standard rod-and-frame test (RFT) (i.e., 1 to 4.5) were compared. A significant stimulus-size effect was found in the EFT, with all subjects becoming morefield-independent, and a significant stimulus-size effect was found in the RFT with the same subjects becoming morefield-dependent. Finally, the EFT performance of the field-dependent and field-independent subjects again displayed a significant interaction with the size of the embedded figures. A parallel-serial processingstyles hypothesis is proposed to account for the EFT data.     

The Vietnam veteran on wal: The relation of post-traumatic stress disorder to criminal behavior

The purpose of this paper is to conceptualize the relationship of Post-Traumatic Stress Disorder (PTSD) in Vietnam veterans to criminal behavior. A conceptual framework is discussed which proposes that the disposition to criminal behavior is determined by whether or not the veteran enters into the survivor mode of functioning as a behavioral defense mechanism against the disorder. It is hypothesized that there exists a relationship between the severity of PTSD and the tendency to commit illegal acts. The Vietnam Era Stress Inventory (Wilson and Krauss, 1980) was used to assess PTSD among a volunteer national sample of Vietnam combat veterans (N = 114) participating in the Veterans Administration's counseling program known as Operation Outreach. The results strongly supported the hypothesis and indicated that combat role variables, exposure to stressors in Vietnam and the severity of PTSD were significantly correlated with criminal acts.     

Cognitive and attentional deficits in children vulnerable to psychopathology

Cognitive and attentional deficits were assessed in children with either a schizophrenic, an affectively disordered or a normal parent. The children were grouped both by their parents' DSM-II diagnoses (broadly defined group of schizophrenics and heterogeneous group of depressives)and by a new set of diagnoses (narrowly defined group of schizophrenics, unipolar depressive group and bipolar group). Children whose parents met the more stringent criteria for schizoprhenia performed somewhat more deviantly than children whose parents met only DSM-II criteria. In addition, the importance of splitting the heterogeneous depressive group into more homogeneous subgroups is indicated by the findings that children of unipolar parents generally could not be distinguished from children whose parents are schizophrenic. On the other hand, children of bipolar parents performed reliably better than children of schizophrenics. These findings are viewed within the context of current high-risk studies and psychological deficit literature and suggest that diagnostic issues require more attention by researchers in these areas.This research was supported by Grant MH 21145 from the National Institute of Mental Health. The authors are indebted to Lina Jandorf for assistance in testing the children and with the data analyses.     

Contingency theory and the distinction between associative and non-associative effects in classical conditioning

There is evidence to suggest that CS-US contingency is the variable that determines the associative effects of a CS. It has been claimed that experiments where contingency is manipulated allow us to distinguish between excitatory and inhibitory associative effects, and suggest a solution to the problem of finding a control procedure for non-associative effects. It is argued, however, that unless we can find a priori grounds for defining a level of contingency at which there are no associative effects, these claims are not justified. The reasons for this are that we have no way of distinguishing experimentally between associative and non-associative contributions to the effect of a CS, and that without such a technique there is no possibility of locating the point of associative neutrality empirically.     

Equal-onset contours of vibrotactile stimuli

Characteristic sensations of “surge” occur at onset of vibratory stimulation, analogous to the experience of musical “attack” in the auditory modality. Such a cutaneous sensation may have a phenomenal reality that is discriminable from the sensitivity to either of its physical determinants of time and intensity. Contours of equal-onset sensation obtained by the method of adjustment permitted the assessment of the relative contributions of these two parameters. Both rise time and intensity were found to be significant factors in the determination of contours of equal-onset sensation obtained by either time adjustment or adjustment of vibratory intensity. Equating onset by intensity adjustment was found to be more difficult than equating onset by time adjustment.     

Additivity of aftereffects of maintained head and eye rotations: An alternative to recalibration

Seven groups of 10 subjects each were exposed to various combinations of left and right head and eye rotations for a period of 10 min. Both head and eye produced significant aftereffects of prior position as measured by pointing at a visible target with the unseen hand, but there was no significant interaction. Thus, aftereffects of sustained head and eye rotation were shown to be additive and to account fully for the results of Craske and Crawshaw (1975). Eye muscle potentiation rather than recalibration may be assumed to be the cause of the altered direction of gaze resulting from exposure to displacing prisms.     

Determinants of the rod and frame effect: The role of retinal size

In Experiment 1, base-out prisms were used to alter perceived size and distance to a luminous rod and frame while the retinal size remained unchanged. The rod-and-frame effect (RFE) was the same, whether the display was viewed directly or through the prisms. In Experiment 2, one large and one small rod-and-frame display were placed at distances such that they produced identical retinal angles. This was replicated at three different sets of distances. Perceived size and distance of the large and small frame of identical retinal angle interacted with the observation distance, such that at near distances the large frame was perceived as larger and farther than the small frame while, at far distances, both types of estimates converged to a constant value. In contrast, the RFE was identical for the large and small frames matched in retinal angle, but diminished with distance. In both experiments, the RFE varied precisely with variation in retinal angle. Implications of the role of retinal angle in the RFE and for the interpretation of individual differences were discussed.     

Anticipated compatibility as a function of attitude or status similarity1

Two experiments explored the effects of self-other discrepancies in attitude or status on judgments of another's desirability as a companion It was found that increasing discrepancy in status or attitudes led to lower judgments of compatibility and liking In one experiment, similarity of attitudes of another was found to correlate with liking him, desire to befriend him, do favors for him, and possibly conform to him. The contribution of some personality measures to the relationship between similarity and anticipated compatibility was a major focus of the study The inhibitory effect of a target's status discrepancy was more pronounced for subjects who were more sensitive to rejection Also, between targets of equally discrepant status, there was a general preference to affiliate with the one whose status was higher than the one whose status was lower–an effect which was even more pronounced for subjects who were sensitive to rejection More anxious subjects judged themselves as generally less acceptable to others, particularly to others of higher status. When predicting attitudes on the basis of limited information, females showed a greater tendency than males to see others as similar to themselves Finally, persons holding different attitudes from one's own were judged as more harmful socially, a bias which was more pronounced in females than in males.     

The Woodlawn school mental health training program: A community-based university graduate course

The observance of traditional jurisdictional boundaries in the training of human service professionals has contributed heavily to the general failure of these professions to provide adequate and effective services. This article describes the rationale, design, and development of a community-based school mental health training program that seeks to establish constructive collaboration between those principals most influential in the mental health of young school children-educators, mental health professionals, parents, and the children themselves. A single curriculum for both professionals and parents and the diversity of professional disciplines involved are two of the unique aspects of this training program.