Color vision but not visual attention is altered in migraine

Objective.-To examine visual search performance in migraine and headache-free control groups and to determine whether reports of selective color vision deficits in migraine occur preattentively. Background.-Visual search is a classic technique to measure certain components of visual attention. The technique can be manipulated to measure both preattentive (automatic) and attentive processes. Here, visual search for colored targets was employed to extend earlier reports that the detection or discrimination of colors selective for the short-wavelength sensitive cone photoreceptors; in the retina (S or "blue" cones) is impaired in migraine. Method.-Visual search performance for small and large color differences was measured in 34 migraine and 34 control participants. Small and large color differences were included to assess attentive and preattentive processing, respectively. In separate conditions, colored stimuli were chosen that would be detected selectively by either the S-, or by the long- (L or "red") and middle (M or "green")-wavelength sensitive cone photoreceptors. Results.-The results showed no preattentive differences between the migraine and control groups. For active, or attentive, search, differences between the migraine and control groups occurred for colors detected by the Scones only, there were no differences for colors detected by the L- and M-cones. The migraine group responded significantly more slowly than the control group for the S-cone colors. Conclusions.-The pattern of results indicates that there are no overall differences in search performance between migraine and control groups. The differences found for the S-cone colors are attributed to impaired discrimination of these colors in migraine and not to differences in attention.