Properties of changing patterns evoking visually perceived oscillation

The aim of this study was to identify some properties of changing proximal stimulus patterns which favor perceived oscillation. By using artificially generated stimulus patterns, it was found that the amount of changes associated with a certain direction of rotation should be small and the rate of these changes low if perceived oscillation was to appear. Great or swift changes were utilized by the visual system to determine perceived direction of rotation, and oscillation was not then reported. It was further found that patterns lacking straight edges perpendicular to the axis of rotation, or with this axis displaced from the middle of the pattern, and patterns with a gradient of texture density were perceived to oscillate more than similar patterns without these properties. Perceived oscillation of ellipses was discussed, and it was concluded that perceived oscillation was a consequence of perceived orientation, which is determined by stimulus properties.     

Contingencies of Exogenous Reward and Task Performance: On the “Minimax” Strategy in instrumental Behavior1

Subjects performed a task in return for monetary payment. In one experimental condition, the subject's pay was contingent on his working at the task for at least the time specified, in another condition, the pay was contingent on the subject's completion of at least the specified output standard; in a third condition, the amount of pay was contingent on the quantity of output. It was found that subjects in the time-contingent condition adhered most closely to the task's time specification, subjects in the standard-contingent condition adhered most closely to the standard specification, and subjects in the output-contingent condition produced the highest quantities of output. The results are discussed in reference to the idea that extrinsically motivated workers act in accordance with a “minimax” strategy: They attempt to perform the bare minimum of work sufficient for the achievement of maximal rewards.