Fig. 1
(a) Frequency spectrum representation of the EEG response at the electrodes of interest (EOI). Neural response to the periodic presentation of original (i.e. intact images; EOI: electrode PO8) vs. scrambled (i.e. phase-scrambled version of the intact images, making it impossible to recognize what was shown originally while preserving the picture properties; EOI: electrode Oz) images (mean (bold) ± 95% within-subject confidence interval (dashed)). Topographic plots show global channel activity at 1.215 Hz (frequency of the oddball) and 6.075 Hz (base image presentation frequency). (b) Comparison of aggregated responses at the oddball and base presentation frequency. Sum of the neural responses at the oddball and base frequency and its first 4 harmonics (summed up separately into the “frequency of interest” for each condition and electrode). Differences between the magnitude of the response were assessed using paired t-tests (nsp>0.05, ****p < 0.0001). Jittered dots (grey) indicate individual data points; horizontal lines link the data points of the same participant for the compared condition. (c) Topographic illustration of the difference between the aggregated oddball response for intact and scrambled images. Aggregated responses consisted of the sum of the 1.215 Hz and its harmonics at 2.43 Hz, 3.645 Hz, 4.86 Hz and 7.29 Hz for each condition. Differences between conditions were assessed using a cluster-based multi-sensor analysis employing a paired t-test (p < 0.0001, right-tailed, 2000 permutations and set to 4 neighbors on average for each electrode).
