Emotional Stroop indices for faces. Emotional Stroop indizes for faces comparing the color naming latencies of negative stimuli with the latencies of neutral stimuli (ESI-N) and comparing the response latencies of negative stimuli with the latencies of positive stimuli (ESI-P). ESI of all three groups are displayed (Co: control group, EM: episodic migraine group; FM: frequent migraine group). Analyses of variances revealed a marginally significant group difference for ESI-P ((*) p=.05), and for ESI-N ((*) p=.075). For both indices there were significant differences between the Co and the FM group (ESI-N: p=.038; ESI-P: p=.016). The ESI-N of the controls differed significantly from zero (t(19) = 3.94, p=.001), whereas the ESI-N of the migraine groups were not significantly different from zero. RT: reaction time.