Pain Affects Visual Orientation: an Eye-Tracking Study

Because of its unique evolutionary relevance, it is understood that pain automatically attracts attention. So far, such attentional bias has mainly been shown for pain-related stimuli whereas little is known about shifts in attentional focus after actual painful stimulation. This study investigated attentional shifts by assessing eye movements into the direction of painful stimulation. Healthy participants were presented either a blank screen or a picture showing a natural scene while painful electrical stimuli were applied to the left or right hand. In general, painful stimulation reduced exploratory behavior as reflected by less and slower saccades as well as fewer and longer fixations. Painful stimulation on the right hand induced a rightward bias (ie, increased initial saccades, total number and duration of fixations to the right hemifield of the screen). Pain applied to the left hand as well as no pain induced a leftward bias that was largest for the direction of first saccades. These findings are in line with previous observations of attentional biases toward pain-related information and highlight eye tracking as a valuable tool to assess involuntary attentional consequences of pain. Future studies are needed to investigate how the observed changes in eye movements relate to pain-induced changes in perception and cognition. Perspective The study investigated pain-induced attentional shifts in terms of reflexive eye movements. This attention-capturing quality of pain should be examined in chronic pain conditions because it might contribute to the cognitive impairments often observed in chronic pain patients.