Fig 1. Experimental design.

Experimental design was identical to Rounis and colleagues [19], apart from exceptions described in methods. Most notably, confidence in choice was used instead of visibility to determine metacognitive judgement. Participants were presented with either a diamond on the left and square on the right or vice versa, followed by a metacontrast mask. They were then required to make a combined judgement as to the stimulus configuration and their level of confidence in that decision. Adapted from Rounis [19] with permission.