Time–frequency plots of ERBP values for each stimulus category. Time is shown on the x-axis (seconds), and frequency (20–60 Hz) is shown on they-axis. Stimulus onset is indicated by the yellow vertical bar at 0 sec. Color encodes ERBP values in decibels. ERBP values were calculated for individual trials and subsequently averaged across 12 channels in which significant responses were seen relative to a 500 msec prestimulus reference period.