Esfuerzo y decremento de vigilancia en tareas de discriminación sucesiva y simultánea

Abstract

The aim of the experiment presented in this paper was to test the hypothesis that decrease of sensitivity in vigilance tasks occurs beCause the attentional resources or effort required by the task cannot be maintained over a long period of time. Two tasks which differed in memory load were compared on three groups of measures: secondary-task performance, subjective effort and cardiovascular activity (mean IBI and 0.1 Hz spectral amplitude). The sensitivity decline observed in both tasks was not significant, although a significant decline was observed in efficiency or in formation-processing rate, indexed by the ratio between accuracy and speed. The data related to subjective effort and secondary-task performance appear not to support the original hypothesis. The main finding was that the amplitude of the mid-band at the beginning of the task could be used as predictor of the performance decrement. If this amplitude is a reliable physiological index of attention, our result suggests that a controlled processing at the beginning of the task prevents the decline of vigilance.