Objects and attributes in divided attention: Surface and boundary systems

A series of experiments investigated concurrent discriminations of surface and nonsurface attributes, including color, brightness, texture, length, location, and motion. In all cases but one, results matched those previously reported: Interference occurred when two discriminations concerned different objects, but not when they concerned the same one. In the two-object case, interference was the same whether discriminations were similar (e.g., two surface discriminations) or different (e.g., one surface, one boundary). Such results support a model of visual attention in which separate visual subsystems are coordinated, converging to work on surface and boundary properties of the same selected object. A partial exception is color: For reasons that are unclear, color escapes twoobject interference except from other, concurrent surface discriminations     

Control of fixation duration in a simple search task

To obtain insight into the control of fixation duration during visual search, we had 4 subjects perform simple search tasks in which we systematically varied the discriminability of the target. The experiment was carried out under two conditions. Under the first condition (blocked), the discriminability of the target was kept constant during a session. Under the second condition (mixed), the discriminability of the target varied per trial. Under the blocked condition, fixation duration increased with decreasing discriminability. For 2 subjects, we found much shorter fixation durations in difficult trials with the mixed condition than in difficult trials with the blocked condition. Overall, the subjects fixated the target, continued to search, and then went back to the target in 5%–55% of the correct trials. In these trials, the result of the analysis of the foveal target was not used for preparing the next saccade. The results support a preprogramming model of the control of fixation duration. In a simple search task, control of fixation duration appears to be indirect.     

The visual perception of rigid motion from constant flow fields

Four experiments investigated observers’ judgments of rigidity for different types of optical motion. The depicted structural deformations were of two types: (1) those with nonparallel image trajectories that are detectable from the first-order spatiotemporal relations between pairs of views; and (2) those with parallel image trajectories that can only be detected from higher order relations among three or more views. Patterns were composed of smooth flow fields in Experiments 1 and 3, and of wire frame figures in Experiments 2 and 4. For both types of display, the nonrigidity detectable from the first-order spatiotemporal structure of the motion sequence was much more salient than the deformation detectable only from the higher order spatiotemporal structure. These results indicate that observers’ judgments of rigidity are based primarily on a two-view analysis, but that some useful information can be obtained under appropriate circumstances from higher order spatiotemporal relations among three or more views.     

Active and passive avoidance following the administration of systemic DSP4, xylamine, or p-chloroamphetamine

Groups of rats were administered either DSP4 (50 mg/kg, ip), xylamine (50 mg/kg, ip), or p-chloroamphetamine (2 X 10 mg/kg, ip), either 2 weeks or 1 week before the testing of two-way active avoidance. DSP4 and xylamine, the selective noradrenaline (NA) neurotoxins, caused a two-way avoidance impairment but p-chloroamphetamine, the selective 5-hydroxytryptamine (5-HT) neurotoxin, did not do so. Pretreatment with desipramine (20 mg/kg, ip) blocked the avoidance impairment caused by DSP4 and xylamine treatment. Neither DSP4 nor xylamine caused any alteration of passive avoidance retention. The biochemical analyses indicated severe NA, but not 5-HT, depletions in the DSP4 and xylamine conditions and drastic 5-HT, but not NA, depletions in the p-chloroamphetamine conditions. These results confirm and extend earlier findings concerning the role of NA in avoidance behavior.     

The making of the group therapist: The role of experiential learning

The purpose of this paper is to review the necessary components of a comprehensive group therapy program. The balancing between the didactic and the experiential portions, and an analysis of the selection criteria, along with the rationale for a particular sequencing of elements in the curriculum, are discussed. A line between supervision and personal therapy is drawn. The author describes the milieu necessary for a successful training program to evolve and makes suggestions for improvements. The various experiential aspects of training are presented and critically evaluated. The training situation is examined from the point of view of the faculty, the trainee and the patients involved. The author marshalls evidence indicating that personal group psychotherapy in a patient group is the preferred form for most trainees for the experiential part of the program. The paper concludes that the sharing and cohesiveness of training philosophies and methods by the faculty is a prerequisite to the success of any training program.     

THE PHYSICS OF DAVID BOHM AND ITS RELEVANCE TO PHILOSOPHY AND THEOLOGY

Abstract. The purpose of this paper is to analyze David Bohm's work in terms of physics, philosophy, and theology. First, I discuss the development of Bohm's thought since 1951. Then, using the methodology of Imre Lakatos, I evaluate the scientific status of his research program. Next, I explore the philosophical dimensions of Bohm's views in which realist and idealist, monist and dualist, contingent and determinist outlooks occur in creative tension. Finally, I suggest ways in which Bohm's ideas are relevant to theology through concepts of God and cosmos, beauty and purpose, grace and free will, church, self and evil.

The entire universe is basically a single, indivisible…but flexible and ever changing, unit (Bohm 1951, 140).

     

The measurement of imagery ability

When variations in imagery ability are used to predict task performance, distinct and consistent relationships do not tend to emerge. A selective review of studies is undertaken to outline some basic reasons why individual difference measures of imagery are often so unsuccessful. Relevant studies concerning the learning and performance of motor skills are examined in some detail. It is concluded that the major problem in these studies is the types of imagery tests that have been employed; these tests have not adequately measured imagery ability. A recently developed instrument, the Movement Imagery Questionnaire, which has been designed to assess individual differences in visual and kinesthetic imagery of movement is discussed.     

The role of personality in crowding research

An analysis of variance was carried out on Ss who were tested with a letter-cancellation task under four experimental conditions, two levels each of crowding and disconfirmation of expectancy. Eight types of Ss were distinguished based on sex and high or low scores on E and N. The crowding situation and disconfirmation of expectancy was found to affect extraverts significantly more than introverts, as predicted by the Brebner-Cooper model. It was confirmed that personality is an important variable in crowding research.     

Social attitudes of schizophrenics

The Wilson-Patterson Conservatism Scale was given to 34 schizophrenic and 34 non-schizophrenic patients in a Dutch mental hospital. The absence of liberal-scoring schizophrenics was interpreted as consistent with the theory that the social withdrawal seen in chronic schizophrenia represents a strategy for coping with stimulus overload. Internal consistency analysis of C scale performance indicated that this test might be used to assess thought disorder in much the same way as the Bannister and Fransella Grid Test, but a great deal more economically. Furthermore, the questionnaire permits a more detailed examination of the source of inconsistency than does the repertory grid method.