Binocular rivalry and emotion: Implications for neural correlates of consciousness and emotional biases in conscious perception

State-dependent alterations of implicit emotional dominance during binocular rivalry in subthreshold depression

Binocular rivalry, a visual perception phenomenon where two or more percepts alternate every few seconds when distinct stimuli are presented to the two eyes, has been reported as a biomarker in several psychiatric disorders. It is unclear whether abnormalities of binocular rivalry in depression could occur when emotional rivaling stimuli are used, and if so, whether an emotional binocular rivalry test could provide a trait-dependent or state-dependent biomarker. In the current study, 34 individuals with subthreshold depression and 31 non-depressed individuals performed a binocular rivalry task associated with implicit emotional processing. Participants were required to report their perceived orientations of the rival gratings in the foreground and to neglect emotional face stimuli in the background. The participants were retested after an approximately 4-month time interval. Compared to the non-depressed group, the subthreshold depression group showed significantly longer perceptual dominance durations of the grating with emotional faces as the background (i.e., implicit emotional dominance) at the initial assessment. However, the abnormality was not found at the follow-up assessment. More importantly, we found smaller changes in depressive severity at the follow-up assessment for individuals displaying longer emotional dominance at the initial assessment than for individuals with weaker emotional dominance. The current emotional binocular rivalry test may provide an objective, state-dependent biomarker for distinguishing individuals with subthreshold depression from non-depressed individuals.

INs and OUTs of faces in consciousness: a study of the temporal evolution of consciousness of faces during binocular rivalry

Contents of consciousness change over time. However, the study of dynamics in consciousness has been largely neglected. Aru and Bachmann have recently brought to the attention of scientists dealing with consciousness the relevance of making inquiries about its temporal evolution. Importantly, they also pointed out several experimental questions as guidelines for researchers interested in studying the temporal evolution of consciousness, including the phases of formation and dissolution of content. They also suggested that these two phases could be characterized by asymmetric inertia. The main objective of the present investigation was to approximate the dynamics of these two phases in the context of conscious face perception. To this aim, we tested the time course of content transitions during a binocular rivalry task using face stimuli and asked participants to map their subjective experience of transitions from one content to the other through a joystick. We then computed metrics of joystick velocity linked to content transitions as proxies of the formation and dissolution phases. We found a general phase effect such that the formation phase was slower than the dissolution phase. Furthermore, we observed an effect specific to happy facial expressions, such that their contents were slower to form and dissolve than that of neutral expressions. We further propose to include a third phase of stabilization of conscious content between formation and dissolution.

Asynchronous neural oscillations associated with subliminal affective face priming in autism spectrum disorder

Autism spectrum disorder (ASD) is characterized by social communicative disturbance. Social communication requires rapid processing and accurate cognition regarding others' emotional expressions. Previous electrophysiological studies have attempted to elucidate the processes underlying atypical face-specific N170 responses to emotional faces in ASD. The present study explored subliminal affective priming effects (SAPEs) on the N170 response and time-frequency analysis of intertrial phase coherence (ITPC) for the N170 in ASD. Fifteen participants [seven participants with ASD and eight typically developing (TD) controls] were recruited for the experiment. Event-related potentials were recorded with a 128-channel electroencephalography device while participants performed an emotional face judgment task. The results revealed enhanced N170 amplitude for supraliminal target-face stimuli when they were preceded by subliminal fearful-face stimuli, in both the ASD and TD groups. Interestingly, TD participants exhibited higher alpha-ITPC in the subliminal fearful-face priming condition in the right face-specific area in the N170 time window. In contrast, there were no significant differences in ITPC in any frequency bands between the subliminal fearful and neutral priming conditions in the ASD group. Asynchronous phase-locking neural activities in the face-specific area may underlie impaired nonconscious face processing in ASD, despite the presence of common features of SAPEs for the N170 component in both the ASD and TD groups.

You see what you avoid: Fear of spiders and avoidance are associated with predominance of spiders in binocular rivalry

What we see is the result of an efficient selection of cues in the visual stream. In addition to physical characteristics this process is also influenced by emotional salience of the cues. Previously, we showed in spider phobic patients that fear-related pictures gain preferential access to consciousness in binocular rivalry. We set out to replicate this in an independent unselected sample and examine the relationship of this perceptual bias with a range of symptom clusters. To this end, we recruited 79 participants with variable degrees of fear of spiders. To induce binocular rivalry, a picture of either a spider or a flower was projected to one eye, and a neutral geometric pattern to the other eye. Participants continuously reported what they saw. We correlated indices of perceptual dominance (first percept, dominance duration) with individual fear of spiders and with scores on specific symptom clusters of fear of spiders (i.e., vigilance, fixation, and avoidance coping). Overall, higher fear of spiders correlates with more predominace of spider pictures. In addition, this perceptual bias is uniquely associated with avoidance coping. Interestingly, this demonstrates that a perceptual bias, which is not intentionally controlled, is linked with an instrumental coping behavior, that has been implicated in the maintenance of pathological fear.

Spatially Filtered Emotional Faces Dominate during Binocular Rivalry

The present investigation explores the role of bottom-up and top-down factors in the recognition of emotional facial expressions during binocular rivalry. We manipulated spatial frequencies (SF) and emotive features and asked subjects to indicate whether the emotional or the neutral expression was dominant during binocular rivalry. Controlling the bottom-up saliency with a computational model, physically comparable happy and fearful faces were presented dichoptically with neutral faces. The results showed the dominance of emotional faces over neutral ones. In particular, happy faces were reported more frequently as the first dominant percept even in the presence of coarse information (at a low SF level: 2-6 cycle/degree). Following current theories of emotion processing, the results provide further support for the influence of positive compared to negative meaning on binocular rivalry and, for the first time, showed that individuals perceive the affective quality of happiness even in the absence of details in the visual display. Furthermore, our findings represent an advance in knowledge regarding the association between the high- and low-level mechanisms behind binocular rivalry.