Robustness to two-object images in human visual cortex
Figure W2: Suppression index for exemplars and categories
Figure W2: Suppression index for exemplars and categories. Throughout this figure, r1 (R1) and r2 (R2) denote the responses to the single-object images containing exemplar 1 (category 1) or exemplar 2 (category 2) and r12 (R12) denotes the responses to the two-object images that contain both exemplars (categories). The IFP response magnitude here is defined as the range of the IFP signal from 50 ms to 300 ms after stimulus onset. The response suppression index was defined as (with a similar definition for R1, R2 and R12). Here we only consider non-target images (that is, images where none of the objects belonged to the target category), electrodes that showed visually-selective responses to single objects (24 electrodes based on one-way ANOVA on the responses to different object categories, p<0.01; Experimental Procedures), images that included the categories that elicited selective responses (n=35) and those images where we had at least 5 repetitions. The blue curve indicates the distribution of the suppression index values for those electrodes that showed enhanced responses to human faces and the gray curve shows the distribution of the suppression index values for those electrodes that showed enhanced responses to categories other than human faces. The black arrow shows the mean of the overall distribution (gray bars); the blue arrow shows the mean of the distribution for faces (blue curve) and the gray arrow shows the mean of the distribution for non-faces (gray curve). We indicate the position of the example electrodes from Figure 1 and Figure S1. Bin size = 0.05. A. Exemplar-based analysis (n=80 exemplar pairs). The suppression index was -0.09±0.16 (mean±s.d.; -0.10±0.18 for those electrodes that preferred human faces and -0.09±0.14 for those electrodes that preferred other categories). B. Category-based analysis (n=140 category pairs). The suppression index was -0.02±0.09 (mean±s.d.; -0.03±0.10 for those electrodes that preferred human faces and 0.01±0.07 for those electrodes that preferred other categories).
Last updated: 1/15/10