Emotional Stroop indices for words. Emotional Stroop indices for words 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). Asterisk indicates significant difference from zero for the FM group in ESI-N, p=.043). One-way ANOVAs did not yield significant group effects for any of the two indices. RT: reaction time.