Multisensory constraints on awareness

Given that multiple senses are often stimulated at the same time, perceptual awareness is most likely to take place in multisensory situations. However, theories of awareness are based on studies and models established for a single sense (mostly vision). Here, we consider the methodological and theoretical challenges raised by taking a multisensory perspective on perceptual awareness. First, we consider how well tasks designed to study unisensory awareness perform when used in multisensory settings, stressing that studies using binocular rivalry, bistable figure perception, continuous flash suppression, the attentional blink, repetition blindness and backward masking can demonstrate multisensory influences on unisensory awareness, but fall short of tackling multisensory awareness directly. Studies interested in the latter phenomenon rely on a method of subjective contrast and can, at best, delineate conditions under which individuals report experiencing a multisensory object or two unisensory objects. As there is not a perfect match between these conditions and those in which multisensory integration and binding occur, the link between awareness and binding advocated for visual information processing needs to be revised for multisensory cases. These challenges point at the need to question the very idea of multisensory awareness.

The compatibility between sociological and cognitive neuroscientific ideas on consciousness: is a neurosociology of consciousness possible?

This article considers the possibility of integrating sociological and cognitive neuroscience ideas on consciousness and developing a new research area: neurosociology of consciousnesses. Research was conducted taking into account the limited knowledge on consciousness produced in these disciplines and the necessity of finding ways to study the social roles concerning the neural correlates of consciousness. Applying several ideas on consciousness from these disciplines (intersubjectivity, close connection with collective forms representations, deriving awareness from the brain's processes, and so on), I show that it is difficult to reconcile the differences in the treatment of consciousness through the simple combination of the different ideas. The integration should be pursued in light of the neuroscientific findings concerning consciousness in different social contexts (role behavior, social interactions, and so on). In integrating the concepts, I predicted the role of time delay in conscious awareness in decision making, synchronization of neural oscillations under conscious perception, and the activations of certain brain zones in correspondence to different conscious cognitive processes for understanding in face-to-face situations. The study reveals that the optimal path for neurosociological research on consciousness is in its primary development without a rigid binding to either sociology or neuroscience.

The relationship between feature binding and consciousness: evidence from asynchronous multi-modal stimuli

Processing the various features from different feature maps and modalities in coherent ways requires a dedicated integration mechanism ("the binding problem"). Many authors have related feature binding to conscious awareness but little is known about how tight this relationship really is. We presented subjects with asynchronous audiovisual stimuli and tested whether the two features were integrated. The results show that binding took place up to 350 ms feature-onset asynchronies, suggesting that integration covers a relatively wide temporal window. We also asked subjects to explicitly judge whether the two features would belong to the same or to the different events. Unsurprisingly, synchrony judgments decreased with increasing asynchrony. Most importantly, feature binding was entirely unaffected by conscious experience: features were bound whether they were experienced as occurring together or as belonging to a separate events, suggesting that the conscious experience of unity is not a prerequisite for, or a direct consequence of binding.