This paper present a proposal for measuring available mental resources during the accomplishment of a task. Our proposal consists in measuring emotions provoked by perceived self-efficacy in the execution of the task. Self-efficacy is one of the most important factors that affect the resources that a person puts at the disposal of the execution of the task. When a person perceives that he/she is not being effective he/she will activate more resources to improve his performance. This self-efficacy will be reflected in the emotions that the person experiences. A good efficacy will provoke positive emotions and a bad efficacy negative emotions. The results of our study show that poor execution leads to negative emotions and psychophysiological activation as measured by pupil dilation. According to these results we propose that a possible method for measuring available resources during the execution of the task could be online measuring of emotions
