Gaze direction and face orientation modulate perceptual sensitivity to faces under interocular suppression

Abstract

Faces convey a wealth of information essential for social interaction. Their importance has prompted suggestions that some facial features may even be processed unconsciously. Evidence for such unconscious processing has predominantly come from the Breaking Continuous Flash Suppression (b-CFS) paradigm, which measures the time it takes different stimuli to overcome interocular suppression. For instance, suppressed upright faces and faces making eye contact are detected faster than inverted faces and faces looking away, respectively. However, the b-CFS procedure suffers from important problems: Observers can decide how much information they receive before committing to a report, so their detection responses may be influenced by differences in decision criteria and by stimulus identification. Here, we first replicated gaze-direction and face-orientation b-CFS effects, and then developed a new procedure that addresses these problems by using predefined exposure durations and measuring sensitivity and decision criteria for both detection of suppressed stimuli (reporting their location on screen) and identification of those stimuli (reporting gaze direction). Importantly, we find higher detection sensitivity to both upright and direct-gaze (compared to inverted and averted-gaze) faces, with no effects on decisional factors. For identification, however, we find both greater sensitivity and more liberal criteria for upright faces. Our findings demonstrate separable influences of face orientation and gaze direction on detection and identification in the access of faces to awareness, as well as the importance of using methods that can dissociate perceptual and decisional processes.

Color Can Shorten Breakthrough Times in Continuous Flash Suppression through Increased Salience and Task Relevance

“…A common criticism of the “breaking CFS” paradigm is that breakthrough times may not only reflect differences in perceptual sensitivity or discriminability [ 53 ]. Participants may also take more or less time to respond, depending on how conservative or liberal they set their response criterion.…”

“…This is because its measures are derived from hit and false alarm rates rather than response times. Still, there is hope that breakthrough time effects do not only reflect differences in response criteria, because research has shown that when perceptual sensitivity is measured directly (e.g., using other masking techniques or with fixed durations of CFS trials), the qualitative pattern of results tends to converge with breakthrough time effects in CFS experiments [ 51 , 53 ].…”

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

“…In the b-CFS variant, participants are asked to report when the target stimulus breaks through suppression into awareness and their latency to do this has been taken as an index of unconscious processing, with the assumption being that faster breakthrough times indicate faster, more efficient, or higher priority unconscious processing. For example, outside of the domain of emotional expressions, Jiang, Costello, & He (2007) found that upright faces break through suppression faster than inverted faces, suggesting that holistic face processing may occur without awareness (Akechi et al, 2015;Gayet & Stein, 2017;Kobylka et al, 2017;Lanfranco et al, 2020;Stein, Senju, et al, 2011).…”

“…In recent work, we have developed a variant on b-CFS that specifically disentangles perceptual sensitivity from decision criterion (Lanfranco et al, 2020). This variant uses the method of constant stimuli: Participants do not decide for themselves how much evidence to accumulate, but instead view stimuli that are CFS-masked for experimentercontrolled amounts of time.…”

“…In this paper, we report a set of studies that aimed to settle the question of whether emotional expressions are processed unconsciously. Our studies built on a new variant of the b-CFS paradigm (see Lanfranco et al, 2020) that addresses concerns about its validity. They used a wide variety of stimuli, to address concerns about generalisation and had high statistical power, in order to address concerns about replicability.…”