Figure 1. Stimuli and Behavior.

(A) Timeline of stimulus presentation (top). Immediately preceding the target image, a scrambled version was presented for a variable time between 0.8 and 1.2 s. Next, the target image was presented for 500 ms and showed either a fearful (50%) or happy (50%) expression. Subjects indicated whether the presented face was happy or fearful by a button press. The target presentation was followed by a variable delay. Target images and associated color code used to identify trial types in later figures are shown (bottom).

(B and C) Behavioral performances from the patients.

(B) Learning curve (top) and reaction time (bottom) (n = 11 and 12 sessions, respectively, mean ± standard error of the mean [SEM]). The inset shows example stimuli for 20, 30, and 40 bubbles revealed. Patients completed on average a total of 421 bubble trials, and the average number of bubbles required ranged from 100 at the beginning to 19.4 ± 7.9 on the last trial (n = 11 sessions, ±standard deviation [SD]; one session omitted here because the learning algorithm was disabled as a control, see results). The average reaction time was fastest for whole faces and significantly faster for whole faces than bubble trials (897 ± 32 ms versus 1,072 ± 67 ms, p < 0.05, n = 12 sessions, relative to stimulus onset).

(C) Behavioral classification image (n = 12 sessions). Color code is the z scored correlation between the presence or absence of a particular region of the face and behavioral performance: the eye and mouth regions conveyed the most information, as described previously [9]. See Figure S1 for further analyses of behavioral performance.