The effects of achievement motivation, task difficulty, and goal difficulty on physiological, behavioral, and subjective effort.

The purpose of the study was to present experimental arguments evaluating the Humphreys and Revelle's model of effort. Two important factors were tested: achievement motivation and difficulty. Heart rate, heart rate variability, blood pressure, facial electromyographic reactivity, and reaction time were measured as an index of effort expenditure. A 2x2x2 factorial design was used with two levels of resultant achievement motivation, two levels of task difficulty, and two levels of goal difficulty. As expected, the 16 participants high in resultant achievement motivation showed a better performance and had a larger decrease of the midfrequency band than the 16 participants low in resultant achievement motivation, especially during the difficult task. Results lend some support for the impact of resultant achievement motivation, task difficulty, and goal difficulty on effort mobilization.