Arousal facilitates involuntary eye movements

Abstract

Attention plays a critical role in action selection. However, the role of attention in eye movements is complicated as these movements can be either voluntary or involuntary, with, in some circumstances (antisaccades), these two actions competing with each other for execution. But attending to the location of an impending eye movement is only one facet of attention that may play a role in eye movement selection. In two experiments, we investigated the effect of arousal on voluntary eye movements (antisaccades) and involuntary eye movements (prosaccadic errors) in an antisaccade task. Arousal, as caused by brief loud sounds and indexed by changes in pupil diameter, had a facilitation effect on involuntary eye movements. Involuntary eye movements were both significantly more likely to be executed and significantly faster under arousal conditions (Experiments 1 and 2), and the influence of arousal had a specific time course (Experiment 2). Arousal, one form of attention, can produce significant costs for human movement selection as potent but unplanned actions are benefited more than planned ones.

Keywords: Antisaccades; Arousal; Attention; Eye movements; Involuntary actions.

Figure 1

A graphic representation of the time line of a typical sound trial in Experiment 1 (on left) or Experiment 2 (on right).

Figure 2

Pupil diameter when the go signal occurred, indexing a physiological change consistent with arousal during sound trials which was present when the action was to be made.

Figure 3

Percentage of involuntary eye movements in the sound and silent conditions in Experiments 1 & 2. Involuntary saccades were significantly increased under conditions of arousal with a specific time course for the increase in involuntary movements. Asterisks indicate significant differences (p< 0.05) between silent and sound conditions.