Search

Individual differences in pupil size are not surprising since they have been well documented by ocular scientists for years, although emphasis has typically been on abnormalities. What may be surprising, however, is the possibility that some of these presumably inherent differences may be related to performance characteristics of the individuals. I would like to discuss some research which suggests that certain pupillary measurements may be useful as performance predictors of individual capabilities, and/or group behavior. Before describing the first study (Peavler, in press), a brief review of some of the previous pupillary research seems appropriate.

It is argued that effects of fatigue on performance should be progressive as time goes on. Initial decrements, often found in vigilance tasks, cannot be ascribed to what is usually called fatigue, but rather reflect a change from a state of hyper-vigilance to normal vigilance occurring within the first half hour of the work period. Studies on very long-term performance, in particular longterm driving, have generally failed to show progressive effects. This casts some doubt on the usual implicit assumption that fatigue and long-term work are uniquely related. It is probable that effects of declining diurnal rhythm, monotony, and accumulating lack of sleep will also contribute to fatigue.

The experiments described in this chapter are of particular interest, for two reasons. In the first place, reminiscence seems to be a particularly stable and sensitive index of motivation; the well-known difficulty of finding many such indicators suggests that we should cherish those we have found with particular care. In the second place, the use of motivation as the independent variable in our experimental design enables us to perform what seem crucial experiments to decide between the inhibition and the consolidation theories.

The understanding of muscle metabolism and its regulation in situ has been greatly advanced in recent years by the analysis of the levels of metabolic intermediates under differing conditions. Only recently has it been possible to perform similar studies in mail. In the present studies muscle samples have been obtained using the needle biopsy technique (1, 10, 11) and the levels of a number of metabolites in these have been determined by enzymatic micro-methods.

We have recently been interested in the physiological adaptations accompanying the performance of a given total amount of work by a variety of patterns of intermittent and continuous exercise.