Hypothesis
For weak, briefly presented and masked stimuli, humans can discriminate above chance without any awareness of them.
What failed
Using a bias-free procedure for measuring subjective confidence, the study found no evidence of unconscious perception: participants’ behaviour matched a Bayesian ideal observer even though the stimuli were visually masked, implying the thresholds for subjective awareness and objective discrimination are effectively the same.
Broken assumption
Above-chance discrimination of masked stimuli can happen without conscious experience.
Why
The authors argue the apparent dissociation in earlier work came from biased measures of subjective awareness, and report an online survey in which most experts acknowledge the lack of convincing evidence while continuing to hold the belief.
From the published paper: Peters et al. eLife, 2015. ↗CC BY