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

Abstract

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.

No evidence for surface organization in Kanizsa configurations during continuous flash suppression

“…That is, our results fail to provide evidence that, during CFS, traditional pacmen stimuli can induce figure-ground processes that might lead to a differential effect for stimuli able to induce a surface percept. This observation is consistent with a broader set of recent studies focusing on the extent to which mid-and high-level stimuli are represented during CFS (Faivre & Koch, 2014;Gayet, Van Der Stigchel, & Paffen, 2014;Hedger, Adams, & Garner, 2015;Hesselmann & Knops, 2014;Hesselmann & Moors, 2015;Heyman & Moors, 2014;Moors, Huygelier, Wagemans, de-Wit, & van Ee, 2015). That is, there is converging evidence that suppressed stimuli are processed to a limited extent during CFS and that any process that requires complex integration of several features of the suppressed stimulus is unlikely to take place.…”

A global attentional scope setting prioritizes faces for conscious detection

“…Past CFS studies have reported that suppression time typically decreases throughout the course of an experimental session (Heyman & Moors, 2014;Stein, Hebart, & Sterzer, 2011). We confirmed this observation in a pilot experiment in which observers completed 120 b-CFS trials in a single experimental session and the suppressive strength of CFS decreased until stimuli broke almost instantaneously in the final 30 trials.…”

“…It did not, but it is important to note that the main effect of object type could be driven by differences in low-level visual properties, which have been shown to exert strong influences on b-CFS results and should be interpreted with caution (Heyman & Moors, 2014; Yang & Blake, 2012). Thus we ran a reduced 2 3 2 mixed ANOVA with a within-subject factor of scope (global vs. local) and a between-subjects factor of face orientation (upright face vs. inverted face), to examine results that would not be confounded by low-level stimulus properties.…”

Between-Subject Variability in the Breaking Continuous Flash Suppression Paradigm: Potential Causes, Consequences, and Solutions

“…This view stemmed from experiments using such variants of interocular suppression as binocular rivalry (Wheatstone, 1838; Alais and Blake, 2005) and flash suppression (Wolfe, 1984). In contrast, b-CFS studies have yielded contradictory findings, with some studies demonstrating that semantic or conceptual information can drive conscious access of initially suppressed visual input (e.g., Mudrik et al, 2011; Yang and Yeh, 2011; Sklar et al, 2012) while other studies have challenged this view (e.g., Heyman and Moors, 2014; Moors et al, 2016; Rabovsky et al, 2016; Stein et al, in press). Investigating the point in time (or the suppressive strength) at which a manipulation impacts conscious access in a b-CFS paradigm might be a valuable tool to resolve this apparent conflict.…”