Figure 2.

Experimental paradigm. To determine the consciousness threshold, a double staircase algorithm was used. A digit target was presented for 17 ms and masked after a variable delay (SOA) by a metacontrast mask composed of four letters. Participants indicated whether they saw the digit or not and were asked to identify the digit presented. If the target was both seen and correctly named, the target–mask SOA was decreased on the next trial, making the target more difficult to consciously perceive. Otherwise (unseen and/or incorrect answers), the target–mask SOA was increased.