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, Natick, MA, USA). Each stimulus subtended 4�� �� 4�� of the visual angle and BMS-754807 ic50 was presented for 72 ms. Stimuli were presented unilaterally in the blind (right) visual field of patient SL, and were placed 7�� above and 12�� lateral to the central fixation point. The location of the stimuli was tailored to SL��s visual field defect, according to her latest Humphrey��s computerized perimetry (Figure ?Figure1B1B). The background had a luminance of 4.89 cd/m2, except for the color session in which the luminance was 15.07 cd/m2. Experimental Procedure Figure ?Figure1C1C illustrates the experimental procedure. Each trial started with the appearance of a central fixation point (400 ms) which lasted throughout the entire trial. Stimulus presentation was preceded by a 1000 Hz warning acoustic tone lasting 150 ms. The interval between the warning tone and stimulus onset was randomized between 200 and 600 ms to avoid expectation. After the stimulus disappeared, SL was asked to report the stimulus feature in a two alternative forced-choice task (2AFC). When discrimination was not possible, she was requested to guess. SL was then asked to report with a binary response whether she perceived the stimulus�� feature or had guessed. In order not to bias her response criterion, patient SL was informed that a stimulus was presented in each trial (i.e., no catch trials were presented). Statistical Analysis For PFKM each of the stimulus features, trials were classified off-line on the basis of ��seen�� and ��guessed�� responses, and the percent accuracy for the feature discrimination was calculated. Accuracy, in the ��seen�� class of responses, indicates SL��s ability to discriminate the feature under the aware condition, while accuracy in the ��guessed�� class of responses, indicates her ability to discriminate the feature under the unaware condition. To assess whether SL��s performance was significantly higher than chance level (50%), we adopted the one-tailed binomial test. Two binomial tests were performed, one for the ��seen�� responses and one for the ��unseen�� responses. Results Accuracy: Seen�CGuessed Task Figures 1E,F show SL��s BLZ945 detection rate and accuracy in discriminating stimulus features under the conscious (i.e., ��seen�� reports) and unconscious (i.e., ��guessed�� reports) conditions. Statistical analyses are reported separately for each stimulus feature. Orientation discrimination Patient SL reported to have guessed the orientation (vertical | horizontal) of the stimuli in almost all of the trials (98.75%) and to have seen the stimulus orientation only in 1.25% of the trials. Given the very low number of trials responded under the aware condition (i.e., ��seen�� reports), these data were not further analyzed. Under the unaware condition (i.e., ��guessed�� reports), SL��s accuracy in orientation discrimination (56.91%) was significantly higher than chance level (p
