Motion perception over long interstimulus intervals.

Recent studies using moving arrays of textured micropatterns have suggested that motion perception can be supported by two mechanisms, one quasilinear and sensitive to the motion of luminance-defined local texture, the other nonlinear and coding motion of contrast-defined envelopes of texture (Baker & Hess, 1998; Boulton & Baker, 1993b). Here we used similar patterns to study motion perception under conditions previously shown to isolate the nonlinear mechanism (low micropattern densities and positive interstimulus intervals [ISIs]. We measured direction discrimination for two-flash apparent motion over a much larger range of ISIs, and susceptibility to masking by incoherently moving "distractor" micropatterns. The results suggest that two nonlinear mechanisms can support motion perception under these conditions. One operates only for relatively short ISIs (less than c. 100 msec), is sensitive to small spatial displacements, and is relatively insensitive to distractor masking. The other operates over much longer ISIs, is insensitive to small spatial displacements, and is highly disrupted by distractor masking. These results are in line with previous studies suggesting that three mechanisms support motion perception.     

Cognitive mediators of pain perception and tolerance

A social learning model of pain perception and tolerance was evaluated. Responses to cold-pressor pain were examined in 4 groups of 20 Ss each. One group was given instruction in cognitive coping strategies, the 2nd was given a monetary incentive contingent on tolerance time, the 3rd was given both cognitive training and monetary reinforcement, and a no-treatment control group was given neither. Incentive and coping instructions significantly increased tolerance but did not alter pain perception. A path analysis indicated that pain tolerance was affected by self-efficacy, which in turn was predicted by pain expectancy and the provision of incentives. Incentive also had an impact on tolerance that was independent of self-efficacy. Pain perception was strongly affected by pain expectancy, but was unrelated to self-efficacy.     

Semantic field,naming, and auditory comprehension in aphasia

The status of semantic fields for 16 target nouns was compared in high and low comprehension aphasics, brain damaged, and normal controls, by measuring latency and miss rate for recognition of six classes of associates, which were presented orally on tape. The ability to name each target was also examined as a function of the integrity of the subject's semantic field for that word. Low comprehension aphasics showed both quantitative and qualitative changes in semantic fields, while milder aphasics showed only mild quantitative impairment, as compared to controls. Both latency and miss rate measures indicated that failure to name a word is associated with reduced semantic field for that word. This result is interpreted as supporting the view that nameing is, in part, determined by the convergence of associations.     

Water drinking induced in sheep by angiotensin--a physiological or pharmacological effect?

The effect of val5-angiotensin II amide on water drinking in sheep was studied against a background of comprehensive data on arterial blood and cerebrospinal fluid angiotensin II levels in sheep under a variety of physiological conditions. Physiological range of blood angiotensin II concentration is 1-100 ng/100 ml. Intravenous infusion of angiotensin II within the physiological range did not increase water drinking. Intracarotid infusion of angiotensin II, or injection into third ventricle or hypothalamus, consistently caused immediate drinking of large amounts of water. Dosages necessary for effect were in the supraphysiological range. Quantitative examination of data in sheep and other species suggests that a physiological role for angiotensin II in thirst is not proved.     

Token economy systems: breakdown and control

Attention is drawn to the relatively high rate of breakdown of token economy programmes, and the reasons for this are considered. Reference is made to the results of a questionnaire circulated to British token economy programmes. Reasons for breakdown are considered in five categories, these being: nonexistent or poor patient selection; inadequate selection and training of nursing and ward staff; lack of definition of the functions of the supervising psychologist; poor co-operation from, and communication with, administrative staff; and active interference by the community. Solutions to these problems are suggested. The value of alternative or additional theoretical frameworks in promoting positive control of token systems is discussed.     

Panel report: Biotechnology Resources Program (BRP)

During the past few years it has become increasingly apparent that even some of the most distinguished biomedical research institutions throughout the country are unable to provide their member scientists with either up-to-date health-relevant research tools or the opportunity to collaborate with innovative experts at the technology/medicine interface. Accordingly, a concerted effort in Biotechnology Resource Sharing was initiated and promoted during fiscal year 1974 and will continue for the forseeable future. The objective is to effect a more nearly equitable distribution of highly specialized research support capabilities in the nation, including especially those institutions having limited biotechnology capabilities but strong biomedical research programs and compelling biotechnology needs.     

A controlled evaluation of token economy procedures with chronic schizophrenic patients

Eighteen chronic schizophrenic patients were allocated to 3 matched groups, one group acting as an own-ward no-treatment control group. The two other groups moved to a token-economy ward, where the token group received contingent tokens, social reinforcement, and informational feedback as a consequence of appropriate behaviour, and where the control group received contingent social reinforcement and feedback with a matched amount of non-contingent tokens. After a 3 month baseline phase, this procedure was followed for a total of 15 months. A continuous assessment system was used with some weekly and monthly assessments, incorporating nursing checklists and ratings, psychiatric ratings, psychological tests, and time-sampling procedures, as well as continuous monitoring of the ward programme. The introduction of contingent tokens had an immediate positive effect in 3 areas of behaviour, but this advantage disappeared over the 15 months owing to the slower but sustained improvement in the control group. Significant improvement was limited to the areas of Social Withdrawal. Appearance and Routine. The patients who improved the most on any measure were those who were initially the most deteriorated. There were paradoxical changes in non-target behaviour, and in symptomatic behaviour. Suggestions and instructions to nurses may play a major part in influencing patient behaviour within and between experimental phases.