The effect of cognitive tasks and verbalization instructions on heart rate and skin conductance.

This study investigated the effects of cognitive tasks and verbalization instructions on heart period (HP) and skin conductance (SC). Two tasks (imagining common scenes and solving mental arithmetic puzzles) were used to test the hypothesis that conditions requiring attention to internal processess (rejection of the environment) are accompanied by cardiac acceleration and SC increases. Each type of task was administered under three instruction conditions: no verbalization, later verbalization and concurrent verbalization. It was found that the imagination task was associated with no significant changes in HP or SC unless the S was preparing to talk or actually talking. Mental arithmetic resulted in cardiac acceleration and SC increase even when no verbalization was required; however, this result is perhaps due to the covert verbalization inherent in the process of solving mental arithmetic problems. Both later and concurrent verbalization also produced significant increases in physiological activation during the arithmetic task. The findings of this study do not support the notion that conditions requiring rejection of the environment are associated with specific physiological changes. Rather the changes are generally attributable to the verbalization requirement. The effects of instructions requiring S to verbalize later are interpreted as due to either a motor set phenomenon or fear of being evaluated while talking.