Figure 3. The influence of pre-stimulus alpha frequency on Bias_centre (cf. Supplementary Tables 6, 7).

a, Bias (across-participants’ mean ± 1 within-subject SEM) is shown for low (1^st tercile, dashed) and high (3^rd tercile, solid) pre-stimulus alpha frequency across pre-stimulus time for 2 experimental designs (rows: (i) ‘yes-no SOA’, (ii) ‘yes-no threshold’) x 3 sensory contexts (columns: no sound, one sound, two sounds). The right most column depicts results where instantaneous frequency estimates were averaged over time. We observed no significant effect of pre-stimulus alpha frequency on bias in any of the experiments (all p > 0.05). Bayes factors (BF) indexing the evidence for H_A relative to H₀ are shown on a log10-scaled ordinate. Purple lines indicate thresholds for at least moderate evidence favouring H₀ (< 1/3) or H_a (> 3)⁷⁷. b, Within subject consistency of bias relationship with alpha frequency over tasks. The difference in bias between low and high alpha frequency (Δbias = bias_low – bias_high) was significantly correlated between the ‘yes-no SOA’ and the ‘yes-no threshold’ experiment only in the ‘1 sound’ and ‘2 sound’ sensory context (see Supplementary Table 7). SEM, Standard error of the mean.