Frequent words do not break continuous flash suppression differently from infrequent or nonexistent words: implications for semantic processing of words in the absence of awareness.

Continuous flash suppression (CFS) has been used as a paradigm to probe the extent to which word stimuli are processed in the absence of awareness. In the two experiments reported here, no evidence is obtained that word stimuli are processed up to the semantic level when suppressed through CFS. In Experiment 1, word stimuli did not break suppression faster than their pseudo-word variants nor was suppression time modulated by word frequency. Experiment 2 replicated these findings, but more critically showed that differential effects can be obtained with this paradigm using a simpler stimulus. In addition, pixel density of the stimuli did prove to be related to suppression time in both experiments, indicating that the paradigm is sensitive to differences in detectability. A third and final experiment replicated the well-known face inversion effect using the same set-up as Experiments 1 and 2, thereby demonstrating that the employed methodology can capture more high-level effects as well. These results are discussed in the context of previous evidence on unconscious semantic processing and two potential explanations are advanced. Specifically, it is argued that CFS might act at a level too low in the visual system for high-level effects to be observed or that the widely used breaking CFS paradigm is merely ill-suited to capture effects in the context of words.