Binary vs. continuous experimental designs for the study of unconscious perceptual processing

Binary vs. continuous conceptualizations of consciousness may have an unstated influence on experimental designs in unconscious perception research. The binary approach aims to compare a conscious condition (e.g., supraliminal, no or weak stimulus masking) to an unconscious condition (e.g., subliminal, heavy stimulus masking). In contrast, continuous designs tend to vary stimulus energy along a near-threshold continuum to determine changes in perception as a function of stimulus energy (or duration). The present study compared two experimental designs, binary vs. continuous, for the influence of target-masked prime stimuli on a Stroop task. The display parameters were inspired by emotional Stroop studies reporting unconscious perception. Neither experiment produced strong evidence of unconscious perception, but the experiment with a continuous design was more informative. We thus recommend sampling a range of near-threshold display parameters to yield straight-forward, unambiguous interpretations.