Van den Bussche, E. 1 & Reynvoet, B. 2
1 Department of Psychology. Vrije Universiteit Brussel. Brussels, Belgium
2 Department of Psychology. Katholieke Universiteit Leuven. Leuven, Belgium
Unconscious processing can reach a sophisticated cognitive level. Therefore, researchers have recently been investigating what distinguishes conscious and unconscious processing. However, many of these studies suffer from critical problems. First, objective tests were used to assess prime visibility, which are heavily debated. Second, the visual strength of the stimuli critically differed in the conscious and unconscious conditions. Third, different experimental paradigms were used, making studies difficult to compare. We therefore developed a paradigm to measure unconscious perception avoiding these problems. A Stroop priming design is used, but additionally participants have to indicate on each trial how certain they are about the identity of the prime using a five-point PAS scale. Critically, this design avoids previous methodological problems: a subjective assessment of prime awareness on a single-trial basis is used; conscious and unconscious trials are separated based on the prime awareness measure, guaranteeing the same stimulus strength in both conditions; this design can be used to study a range of cognitive effects, making results more easily comparable. A series of pilot studies were conducted to optimize this paradigm. Importantly, we observed Stroop priming for both conscious and unconscious trials, making this design a fruitful approach to measuring unconscious perception.