Dimensions of Perception: 3D Real-Life Objects Are More Readily Detected Than Their 2D Images

Most of our interactions with our environment involve manipulating real 3D objects. Accordingly, 3D objects seem to enjoy preferential processing compared with 2D images, for example, in capturing attention or being better remembered. But are they also more readily perceived? Thus far, the possibility of preferred detection for real 3D objects could not be empirically tested because suppression from awareness has been applied only to on-screen stimuli. Here, using a variant of continuous flash suppression (CFS) with augmented-reality goggles (“real-life” CFS), we managed to suppress both real 3D objects and their 2D representations. In 20 healthy young adults, real objects broke suppression faster than their photographs. Using 3D printing, we also showed in 50 healthy young adults that this finding held only for meaningful objects, whereas no difference was found for meaningless, novel ones (a similar trend was observed in another experiment with 20 subjects, yet it did not reach significance). This suggests that the effect might be mediated by affordances facilitating detection of 3D objects under interocular suppression.

Holistic face processing is influenced by non-conscious visual information

Holistic face processing has been widely implicated in conscious face perception. Yet, little is known about whether holistic face processing occurs when faces are processed unconsciously. The present study used the composite face task and continuous flash suppression (CFS) to inspect whether the processing of target facial information (the top half of a face) is influenced by irrelevant information (the bottom half) that is presented unconsciously. Results of multiple experiments showed that the composite effect was observed in both the monocular and CFS conditions, providing the first evidence that the processing of top facial halves is influenced by the aligned bottom halves no matter whether they are presented consciously or unconsciously. However, much of the composite effect for faces without masking was disrupted when bottom facial parts were rendered with CFS. These results suggest that holistic face processing can occur unconsciously, but also highlight the significance of holistic processing of consciously presented faces.

Diffusion model-based understanding of subliminal affective priming in continuous flash suppression

Affective states influence our decisions even when processed unconsciously. Continuous flash suppression (CFS) is a new variant of binocular rivalry that can be used to render the prime subliminal. Nonetheless, how prior information from emotional faces suppressed by CFS influences subsequent decision-making remains unclear. Here, we employed a CFS priming task to examine the effect of the two main types of information conveyed by faces, i.e., facial identity and emotion, on the evaluation of target words as positive or negative. The hierarchical diffusion model was used to investigate the underlying mechanisms. A significant interaction effect on response time was observed following the angry face prime but not the happy or neutral face primes. The results of the diffusion model analyses revealed that the priming effects of facial identity were mapped onto the drift rate and erased the ‘positive bias’ (the processing advantage of positive over negative stimuli). Meanwhile, the positive emotional faces increased the nondecision time in response to negative target words. The model-based analysis implies that both facial identity and emotion are processed under CFS.

Intact prioritization of fearful faces during continuous flash suppression in psychopathy

Affective state recognition and in particular the identification of fear is known to be impaired in psychopathy. It is unclear, however, whether this reflects a deficit in basic perception (‘fear blindness’) or a deficit in later cognitive processing. To test for a perceptual deficit, 63 male incarcerated offenders, assessed with the Hare Psychopathy Checklist-Revised (PCL-R), and 59 age-matched control participants detected fearful, neutral, and happy facial expressions rendered invisible through continuous flash suppression (CFS), a strong interocular suppression technique. Consistent with previous CFS studies on children, student and community samples, fearful faces were detected faster than neutral faces, which were detected faster than happy faces. Detection of emotional faces was unimpaired in offenders, with strong evidence for a full-blown fear advantage. Moreover, the fear advantage was not reduced in the 20 offenders qualifying as psychopaths according to the PCL-R, and there was no correlation between the fear advantage and PCL-R scores in the 63 incarcerated offenders. These results show that basic visual detection of fearful faces is unimpaired in psychopathy. Deficits in the processing of fearful facial expressions in psychopathy may thus not reflect fear blindness, but impairments at later post-perceptual processing stages related to attention, memory, decision-making, or language.