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An experiment was performed to investigate whether the duration of exposure and the size of the test objects are factors critical for obtaining a training effect in peripheral visual acuity. Contrary to previous results it is shown that considerable improvement may be obtained even under conditions of flash stimulation, provided that the test object used for training is sufficiently small to be just discriminable. The results are interpreted in terms of shifts in the maximum momentary level of attention from the central to the peripheral area of the visual field.

Nine experiments designed to investigate the effect of food deprivation on perceptual-cognitive processes are examined in detail. An effect is revealed in only some of these experiments. The deviating results are explained by assuming that motivational state will not affect perceptual-cognitive processes unless the material presented is meaningful in relation to the motivational state. An examination of the operational definitions given of the processes studied indicate that the processes may be more meaningfully termed imaginary than perceptual. An examination of the operational definition of the motivational state of hunger revealed that in most of the experiments the important condition may not be hours of food deprivation, but the expectancy of the Ss as to when they may next receive food.

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