Figure 7. Testing conscious access in a psychological setting.

(A) A face or a scrambled face was briefly displayed and then masked with a high-contrast image. Display duration of 200 ms was used for supraliminal presentation. The near-threshold face presentation was individualized by an adaptive staircase procedure. The threshold duration was 33 ms in 17 out of 19 participants (see Method details).

(B) Each trial started with a brief flash of face or scrambled face image. Participants were instructed to view the stimuli but not respond until a red fixation cross prompt appeared on the screen. They were required to report whether they had seen a face or not. After their button press response, an unpredictably long rest period with a white fixation cross was used to separate trials (19.5-s mean duration; 1.5-s steps).

(C) The duration of the rest periods followed an exponential distribution.

(D) Behavioral results. The hit rates (p[present|present]) and correct rejections (p[absent|absent]) of a face were 91% (SD = 5.9%) and 96% (SD = 8.5%) in supraliminal conditions and 60% (SD = 19.3%) and 96% (SD = 8.8%) in near-threshold conditions. Significant differences in those rates were found between the near-threshold face and all other conditions (*p < 0.001).

(E) Group-level z-maps of stimulus-induced activity for near-threshold seen versus unseen of a face. The z-maps were thresholded at cluster level α< 0.05.

(F) Time courses of fMRI signal change for near-threshold seen versus unseen in the AIC, DLPFC, ACC, and Thal.

(G) Time courses of spatial similarity for DAT+ and DMN+. *p < 0.01 (paired sample t tests); n.s., non-significance. Shaded areas and error bars indicate ± SEM across subjects (n = 19).