ABSTRACT
In our review of “stress” effects, the factors discussed so far relate mainly to the nature of the task, or to the external environment in which the task is performed. The existence of endogenous circadian rhythms demonstrates that performance is sensitive to the internal, physiological environment also. Further influences of this kind relate to “lifestyle”, including the person’s physical health, the nutrition they receive from their diet, and the effects of socially approved drugs such as nicotine, alcohol and caffeine. In considering these factors, we shall revisit some of the main themes of stress research already considered. All the influences listed affect brain functioning, and there are psychobiological explanations for their effects on performance. However, people also have beliefs and expectancies which may influence performance independently, or in interaction with psychobiological mechanisms. Stimulant drugs are often taken specifically to enhance performance, for example. It is generally believed that strong coffee improves functioning late at night. Hence, one general question to be addressed is the extent to which lifestyle influences depend on physiology, expectancy or both.
