[Effects of task attentiveness on task-irrelevant activity and boredom in the signal detection tasks].

It has been reported that subsidiary behavior, including body movements, and irrelevant thoughts occur spontaneously during a vigilance situation. These activities are called task-irrelevant activity. To examine the effects of task attentiveness on task-irrelevant activity and on the subjective feeling of boredom, 31 subjects were asked to engage in two types of signal detection tasks. The body movements were measured by recording the rotating angle of a swivel chair that the subject sat on. More task-irrelevant thoughts and subsidiary behavior occurred accompanied by higher subjective feeling of boredom in the low attentive task than in the high attentive task. These findings indicate the possibility of the task-irrelevant activity as an index of subjective boredom.