Eyeblink frequency, rehearsal activity, and sympathetic arousal.

Previous studies have suggested that the endogenous eyeblink rate (EBR) is inhibited by visual attention and increased by sympathetic arousal as well as by verbalization. As for the latter variable, it has been suggested that verbalization increases EBR by spreading of electric activity in efferent adjacent vocal and eye-motor pathways. The present study was designed in order to examine whether subvocal ("rehearsal") activity also elicits an increase in EBR. Subjects saw slides depicting either verbal or pictorial information. Subsequently, they were asked to rehearse this information silently. Spontaneous electrodermal fluctuations (SFs) were monitored throughout the experiment. The results clearly show that slide presentation ("information uptake") is accompanied by decrease in EBR, while silent rehearsal of information is accompanied by increase in EBR. Furthermore, this increase in EBR was found to correlate positively with SFs. Thus, results confirm the modulatory influences of visual attention, arousal and (sub)vocal activity on EBR. Furthermore, they suggest an explanation for the relationship that has been found between depressive mood and increased EBR. That is, heightened EBR in depression may reflect subvocal activity ("rumination").