Neural correlates of unconscious processing in functional magnetic resonance imaging: does brain activity contain more information than can be consciously reported?
Neuroscience of consciousness January 1, 2025 Joaquim Streicher, Sascha Meyen, Volker H Franz et al.
A common method for studying unconscious processing compares participants' ability to consciously detect a stimulus with an indirect measure of processing, such as reaction time or brain activity. If the direct measure shows no awareness but the indirect measure shows a significant effect, researchers conclude the stimulus was processed unconsciously. However, this reasoning rests on a statistical fallacy: the sensitivities of the two measures are never directly compared. Reanalyzing 80 experimental conditions from 16 fMRI studies, only eight provided evidence for unconscious processing when sensitivities were properly compared. This suggests that the scope of unconscious processing—both its capacity and the brain areas involved—has been overestimated.