Fig. 5

Overlay of group average data for correct and incorrect trials extracted in gamma band (31.48 - 49.16 Hz) during encoding stage. Gamma increased significantly preceding incorrect relative to correct trials for both groups (paired-samples t tests; HC, t(11) = 5.37, p < 0.0005; SZ, t(39) = 7.01, p < 0.0005) and interacted by group (Wilk's Λ = 0.86, F _{(1, 50)} = 8.46, p = 0.005), with HC evidencing significantly greater range of modulation by accuracy level. Data submitted to statistical analysis was extracted from 1000-7000 ms, essentially containing the period of 200 ms prior to onset of first stimuli in set to 200 ms following onset of the 5^th stimuli of the memory set (or 1400 ms following offset of the 4^th stimuli). Importantly, as depicted in the figure, differences in gamma activity by accuracy were present before onset of first stimuli of each trial (0-1200 ms) and, therefore, are not interpreted to represent a memory load effect in these data