ABSTRACT
In an attempt to observe the energy demands during the performance of a mental task, whole body oxygen consumption was measured ehile cubjects solved a series of abstract reasoning problems of different levels of difficulty. Simultaneously, cardiovascular activity and peripheral temperature were recorded. The measurement of oxygen consumption failed to indicated any changes in energy requirement related to information processing; but when subjects were classified according to their oxygen consumption during the initial period, a positive correlation between changes in oxygen consumption and performance with the most difficult tasks was observed. Thus, correlations between body oxygen consumption and cognitive work can be appreciated only with very high levels of task difficulty, and when variations due to "stress" are normalized. Almost all cardiovascular measurements were sensitive to the esperimental task, although none responded diferently when the level of dificulty varied. Heart Rate Variability (HRV) showed the most regular and significant pattern of change. Some specific patterns of physiological reactivity emerged in relation to personality and emotional characteristics of the subjects and to the level of cognitive demand. Of special interes is the opposite correlation found oxygen consumption, and extroversion with tasks of medium difficulty