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).
