The importance of awareness in face processing: A critical review of interocular suppression studies

Physiological arousal underlies preferential access to visual awareness of fear-conditioned (and possibly disgust-conditioned) stimuli.

“…We believe that the current study provides convincing evidence for the modulation of early visual processing by homeostatically relevant stimuli. Key strengths of this study include that we (a) demonstrate enhanced perceptual access for distinct types of negative valence, (b) build on arousal measurements to support our valence-based interpretations, and (c) control for confounding factors in accordance with recent guidelines for b-CFS research (Lanfranco et al, 2023a, 2023b; Stein, 2019). By presenting CS+/CS− stimuli at intensities converging towards individual threshold levels in a nonspeeded accuracy-based task design, we successfully controlled for postperceptual factors, such as differences in response criteria or postdetection response speeds, possibly present in paradigms based on response time measurements.…”

“…Also, the use of a conditioning-based approach reduced the number of possible confounds as the initially neutral stimuli were matched in terms of low-level salience (such as luminance, contrast, size, or spatial frequency) and did not include any higher-order information that could be associated with naturally threatening or disgusting stimuli. This approach likely yields more robust effects and reduces the risk of future failed replications (e.g., findings on emotional perception using natural objects or faces frequently boil down to factors unrelated to experimental manipulation, such as low-level differences or presence of social cues; Lanfranco et al, 2023b). Indeed, a picture that emerges from conditioning-based studies on visual perception of threat (cf.…”

Assessing the influence of emotional expressions on perceptual sensitivity to faces overcoming interocular suppression.

“…Recent studies have suggested that the advantage of emotional over nonemotional expressions found with the bCFS procedure may have been due to low-level features like spatial frequency and contrast (Gelbard-Sagiv et al, 2016; Schlossmacher et al, 2017; Stein et al, 2018; for a review, see Lanfranco et al, 2023). It could be argued that the fact that we only controlled luminance and still did not find an advantage of emotional expressions suggests that low-level differences are not the only cause of previously reported effects.…”

“…While unconscious processing of emotional expressions has been evaluated using a number of different experimental techniques, the most prominent evidence that such expressions enjoy preferential access to awareness has come from the bCFS paradigm (Lanfranco et al, 2023). In CFS, stimuli are masked by presenting them to only one eye, while a continuous stream of high-contrast Mondrian-like masks is shown to the other eye, dominating awareness.…”

“…For example, some unconscious emotional processing results have been attributed to processing of low-level features rather than emotional content (Gray et al, 2013; Stein et al, 2018), and findings of emotion processing under CFS have been inconsistent (e.g., Schlossmacher et al, 2017), precluding consensus on underlying mechanisms. We describe these issues in more detail below, and also address the different processes that might underlie responses in the main paradigm used to generate these data, the bCFS technique (for reviews, see Lanfranco et al, 2023; Stein, 2019). These considerations raise the question of which of the many processes that influence RTs in perceptual reports is affected by emotional expressions; elucidating this issue would constrain the conclusions that can be drawn from such studies.…”