Criteria for unconscious cognition: three types of dissociation.

To demonstrate unconscious cognition, researchers commonly compare a direct measure (D) of awareness for a critical stimulus with an indirect measure (I) showing that the stimulus was cognitively processed at all. We discuss and empirically demonstrate three types of dissociation with distinct appearances in D-I plots, in which direct and indirect effects are plotted against each other in a shared effect size metric. Simple dissociations between D and I occur when I has some nonzero value and D is at chance level; the traditional requirement of zero awareness is necessary for this criterion only. Sensitivity dissociations only require that I be larger than D; double dissociations occur whensome experimental manipulation has opposite effects on I and D. We show that double dissociations require much weaker measurement assumptions than do other criteria. Several alternative approaches can be considered special cases of our framework.