RA was found to have a considerable impact on occupational balance. The experience is not invariably seen as negative as previous literature would suggest. Further research should explore the longitudinal dimension of occupational balance in people with RA.

In Experiment 1 rats were trained to press a lever on a variable-ratio schedule of food presentation and were then exposed to progressively increasing magnitudes of food reinforcement. Response running rates (rates exclusive of the postreinforcement pause) were found to increase as a function of increasing reinforcement magnitudes. The effect of reinforcement magnitude on response rates inclusive of the postreinforcement pause, however, was less pronounced. Increases in the magnitude of reinforcement were also found to increase the length of the postreinforcement pause. Rats in Experiment 2 were trained to respond on a chained differential-reinforcement-of-low-rate variable-ratio schedule, and were exposed to increasing magnitudes of reinforcement as in Experiment 1. Response running rates increased in the variable-ratio component but decreased in the other component of the schedule. The results are discussed with reference to incentive accounts of reinforcement and the action of reinforcement on the response units generated by the operative contingencies.

Wohlgemuth, having measured the duration of the motion aftereffect (MAE), instructed subjects to close their eyes immediately after adaptation for a period of time longer than the MAE. Upon opening their eyes the subjects reported a residual effect, albeit somewhat shorter than the original effect. Thus the decay of the aftereffect appeared to have been retarded by the period of darkness. This effect is known as 'storage' and poses a problem for any model of the MAE based on the fatiguing of direction-selective units in the visual pathway. A reexamination is made of storage of the MAE, again concentrating on the intervening stimulation between movement adaptation and aftereffect test. The results suggest that the nature of the intervening pattern between adaptation and test conditions is remarkably unimportant. A total of 11 different storage patterns were examined after adaptation to high-contrast drifting horizontal sinewave gratings. For 10 of these patterns large and robust storage effects were found. The exception occurred when the spatial pattern of the storage stimulus was identical to the adaptation and test stimuli. It is proposed that storage cannot be understood in terms of a simple fatigue model of the MAE and that one component of the effect may share similarities with contingent aftereffects.

The study is concerned with evaluating interactions at the organic level within the visual perception subsystem of living systems. The reported work focuses on the identification of some of the determinants of multistable perception by experimentally testing a nonlinear dynamical systems (catastrophe) model of the Necker Cube. This technique serves as an advantage over linear threshold models which cannot effectively study multivalued functional relationships. It was proposed that manipulation of two independent control parameters (bias or changing shape by continuously varying perspective lines and selective stimulus shading) was compatible with the subjective dichotomy of bistable perception of the Necker cube. One hundred and twenty naive subjects, categorized by age, sex, and optical aids, were presented with a computer-generated sequence of 63 stimuli (7 shading levels X 9 perspective levels) to which they had to respond as to whether they saw a "hollow" or "solid" image. The work revealed that bias and shading exerted their effects in opposition and that each influenced the other. Both were decisive factors involved in the perception of the cube. These findings are supported by topological and psychological evidence.

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