Liad Mudrik

Integration Without Awareness Expanding the Limits of Unconscious Processing

Human conscious awareness is commonly seen as the climax of evolution. However, what function—if any—it serves in human behavior is still debated. One of the leading suggestions is that the cardinal function of conscious awareness is to integrate numerous inputs—including the multitude of features and objects in a complex scene—across different levels of analysis into a unified, coherent, and meaningful perceptual experience. Here we demonstrate, however, that integration of objects with their background scenes can be achieved without awareness of either. We used a binocular rivalry technique known as continuous flash suppression to induce perceptual suppression in a group of human observers. Complex scenes that included incongruent objects escaped perceptual suppression faster than normal scenes did. We conclude that visual awareness is not needed for object-background integration or for processing the likelihood of an object to appear within a given semantic context, but may be needed for dealing with novel situations.

Information integration without awareness

Information integration and consciousness are closely related, if not interdependent. But, what exactly is the nature of their relation? Which forms of integration require consciousness? Here, we examine the recent experimental literature with respect to perceptual and cognitive integration of spatiotemporal, multisensory, semantic, and novel information. We suggest that, whereas some integrative processes can occur without awareness, their scope is limited to smaller integration windows, to simpler associations, or to ones that were previously acquired consciously. This challenges previous claims that consciousness of some content is necessary for its integration; yet it also suggests that consciousness holds an enabling role in establishing integrative mechanisms that can later operate unconsciously, and in allowing wider-range integration, over bigger semantic, spatiotemporal, and sensory integration windows.

Multisensory Integration in Complete Unawareness Evidence From Audiovisual Congruency Priming

Multisensory integration is thought to require conscious perception. Although previous studies have shown that an invisible stimulus could be integrated with an audible one, none have demonstrated integration of two subliminal stimuli of different modalities. Here, pairs of identical or different audiovisual target letters (the sound /b/ with the written letter “b” or “m,” respectively) were preceded by pairs of masked identical or different audiovisual prime digits (the sound /6/ with the written digit “6” or “8,” respectively). In three experiments, awareness of the audiovisual digit primes was manipulated, such that participants were either unaware of the visual digit, the auditory digit, or both. Priming of the semantic relations between the auditory and visual digits was found in all experiments. Moreover, a further experiment showed that unconscious multisensory integration was not obtained when participants did not undergo prior conscious training of the task. This suggests that following conscious learning, unconscious processing suffices for multisensory integration.

Unconscious auditory information can prime visual word processing: A process-dissociation procedure study☆

Whether information perceived without awareness can affect overt performance, and whether such effects can cross sensory modalities, remains a matter of debate. Whereas influence of unconscious visual information on auditory perception has been documented, the reverse influence has not been reported. In addition, previous reports of unconscious cross-modal priming relied on procedures in which contamination of conscious processes could not be ruled out. We present the first report of unconscious cross-modal priming when the unaware prime is auditory and the test stimulus is visual. We used the process-dissociation procedure [Debner, J. A., & Jacoby, L. L. (1994). Unconscious perception: Attention, awareness and control. Journal of Experimental Psychology: Learning, Memory, and Cognition, 20, 304-317] which allowed us to assess the separate contributions of conscious and unconscious perception of a degraded prime (either seen or heard) to performance on a visual fragment-completion task. Unconscious cross-modal priming (auditory prime, visual fragment) was significant and of a magnitude similar to that of unconscious within-modality priming (visual prime, visual fragment). We conclude that cross-modal integration, at least between visual and auditory information, is more symmetrical than previously shown, and does not require conscious mediation.

Synchronous contextual irregularities affect early scene processing: replication and extension.

Whether contextual regularities facilitate perceptual stages of scene processing is widely debated, and empirical evidence is still inconclusive. Specifically, it was recently suggested that contextual violations affect early processing of a scene only when the incongruent object and the scene are presented a-synchronously, creating expectations. We compared event-related potentials (ERPs) evoked by scenes that depicted a person performing an action using either a congruent or an incongruent object (e.g., a man shaving with a razor or with a fork) when scene and object were presented simultaneously. We also explored the role of attention in contextual processing by using a pre-cue to direct subjects׳ attention towards or away from the congruent/incongruent object. Subjects׳ task was to determine how many hands the person in the picture used in order to perform the action. We replicated our previous findings of frontocentral negativity for incongruent scenes that started ~ 210 ms post stimulus presentation, even earlier than previously found. Surprisingly, this incongruency ERP effect was negatively correlated with the reaction times cost on incongruent scenes. The results did not allow us to draw conclusions about the role of attention in detecting the regularity, due to a weak attention manipulation. By replicating the 200-300 ms incongruity effect with a new group of subjects at even earlier latencies than previously reported, the results strengthen the evidence for contextual processing during this time window even when simultaneous presentation of the scene and object prevent the formation of prior expectations. We discuss possible methodological limitations that may account for previous failures to find this an effect, and conclude that contextual information affects object model selection processes prior to full object identification, with semantic knowledge activation stages unfolding only later on.

Low-level awareness accompanies “unconscious” high-level processing during continuous flash suppression

The scope and limits of unconscious processing are a matter of ongoing debate. Lately, continuous flash suppression (CFS), a technique for suppressing visual stimuli, has been widely used to demonstrate surprisingly high-level processing of invisible stimuli. Yet, recent studies showed that CFS might actually allow low-level features of the stimulus to escape suppression and be consciously perceived. The influence of such low-level awareness on high-level processing might easily go unnoticed, as studies usually only probe the visibility of the feature of interest, and not that of lower-level features. For instance, face identity is held to be processed unconsciously since subjects who fail to judge the identity of suppressed faces still show identity priming effects. Here we challenge these results, showing that such high-level priming effects are indeed induced by faces whose identity is invisible, but critically, only when a lower-level feature, such as color or location, is visible. No evidence for identity processing was found when subjects had no conscious access to any feature of the suppressed face. These results suggest that high-level processing of an image might be enabled by-or co-occur with-conscious access to some of its low-level features, even when these features are not relevant to the processed dimension. Accordingly, they call for further investigation of lower-level awareness during CFS, and reevaluation of other unconscious high-level processing findings.

Review: me & my brain: Exposing neuroscience's closet dualism

Our intuitive concept of the relations between brain and mind is increasingly challenged by the scientific world view. Yet, although few neuroscientists openly endorse Cartesian dualism, careful reading reveals dualistic intuitions in prominent neuroscientific texts. Here, we present the “double-subject fallacy”: treating the brain and the entire person as two independent subjects who can simultaneously occupy divergent psychological states and even have complex interactions with each other—as in “my brain knew before I did.” Although at first, such writing may appear like harmless, or even cute, shorthand, a closer look suggests that it can be seriously misleading. Surprisingly, this confused writing appears in various cognitive-neuroscience texts, from prominent peer-reviewed articles to books intended for lay audience. Far from being merely metaphorical or figurative, this type of writing demonstrates that dualistic intuitions are still deeply rooted in contemporary thought, affecting even the most rigorous practitioners of the neuroscientific method. We discuss the origins of such writing and its effects on the scientific arena as well as demonstrate its relevance to the debate on legal and moral responsibility.

Are incongruent objects harder to identify? The functional significance of the N300 component

ABSTRACT Objects in the real world typically appear within a broader context, having relationships with the environment. Do these relations between objects and the contexts in which they appear affect object identification? Previous findings of an N300 component evoked by scene‐incongruent objects were taken as evidence for such an effect, since N300 is held to reflect object identification processes. Yet this conjuncture was never directly tested, and ignores differences between the fronto‐central incongruency‐evoked N300 and the typically bi‐polar fronto‐occipital identification‐related N300. Here, the possible influence of context on object identification was examined by manipulating both object‐scene congruency and object identifiability. N300 effects were found both for incongruity and for identifiability, in line with previous studies. Critically, a comparison of divergence times of waveforms evoked by congruent/incongruent objects and waveforms evoked by unidentifiable objects showed that incongruent objects started to diverge from unidentifiable ones later than congruent objects did. This provides first direct evidence for the effect of scene context on object identification; arguably, rapidly extracted gist activates scene‐congruent schemas which facilitate the identification of congruent objects in comparison to incongruent ones. HighlightsObject‐scene congruency and object identifiability were manipulated.N300 was found for both, yet with a different distribution.Later divergence of incongruent than congruent objects from unidentifiable objects.First direct evidence for scene context effects on object identification.

Evidence for Implicit—But Not Unconscious—Processing of Object-Scene Relations

Is consciousness necessary for integration? Findings of seemingly high-level object-scene integration in the absence of awareness have challenged major theories in the field and attracted considerable scientific interest. Lately, one of these findings has been questioned because of a failure to replicate, yet the other finding was still uncontested. Here, we show that this latter finding—slowed-down performance on a visible target following a masked prime scene that includes an incongruent object—is also not reproducible. Using Bayesian statistics, we found evidence against unconscious integration of objects and scenes. Put differently, at the moment, there is no compelling evidence for object-scene congruency processing in the absence of awareness. Intriguingly, however, our results do suggest that consciously experienced yet briefly presented incongruent scenes take longer to process, even when subjects do not explicitly detect their incongruency.

Information integration without awareness: (Trends in Cognitive Sciences 18, 488–496; September, 2014)

The citations in this Review article were renumbered incorrectly at the copyediting stage. The incorrect numbering affected references numbered 80 through 100. The reference numbering has now been fixed in the article online.