Heart Rate and Respiratory Responses as a Function of Task Difficulty: The Use of Discriminant Analysis in the Selection of Psychologically Sensitive Physiological Responses

Abstract

ABSTRACTThe relationship between physiological response patterns.and task difficulty was investigated by evaluating heart rate and respiratory responses during a choice reaction lime tusk with three levels of task difficulty. The data fit a two‐component model or attention containing reactive and sustained responses. There were two reactive responses: An immediate deceleration which was independent of task manipulation; and a short latency response, monotonically paralleling task difficulty, which was characterized by acceleration and an increase in heart rate variability. The sustained component exhibited task dependent deceleration and u generalized reduction in heart rate variability and respiration amplitude variability. A stepwise discriminant analysis was performed on the task conditions using physiological responses to determine responses sensitive to task demands. Physiological response patterns were monotonically ordered as a function of task difficulty, suggesting that this technique may have advantages for determining physiological responses most sensitive to psychological manipulation.