On the Neural Mechanisms Subserving Consciousness and Attention

Consciousness, as described in the experimental literature, is a multi-faceted phenomenon, that impinges on other well-studied concepts such as attention and control. Do consciousness and attention refer to different aspects of the same core phenomenon, or do they correspond to distinct functions? One possibility to address this question is to examine the neural mechanisms underlying consciousness and attention. If consciousness and attention pertain to the same concept, they should rely on shared neural mechanisms. Conversely, if their underlying mechanisms are distinct, then consciousness and attention should be considered as distinct entities. This paper therefore reviews neurophysiological facts arguing in favor or against a tight relationship between consciousness and attention. Three neural mechanisms that have been associated with both attention and consciousness are examined (neural amplification, involvement of the fronto-parietal network, and oscillatory synchrony), to conclude that the commonalities between attention and consciousness at the neural level may have been overestimated. Last but not least, experiments in which both attention and consciousness were probed at the neural level point toward a dissociation between the two concepts. It therefore appears from this review that consciousness and attention rely on distinct neural properties, although they can interact at the behavioral level. It is proposed that a “cumulative influence model,” in which attention and consciousness correspond to distinct neural mechanisms feeding a single decisional process leading to behavior, fits best with available neural and behavioral data. In this view, consciousness should not be considered as a top-level executive function but should rather be defined by its experiential properties

Follow the sign! Top-down contingent attentional capture of masked arrow cues

Arrow cues and other overlearned spatial symbols automatically orient attention according to their spatial meaning. This renders them similar to exogenous cues that occur at stimulus location. Exogenous cues trigger shifts of attention even when they are presented subliminally. Here, we investigate to what extent the mechanisms underlying the orienting of attention by exogenous cues and by arrow cues are comparable by analyzing the effects of visible and masked arrow cues on attention. In Experiment 1, we presented arrow cues with overall 50% validity. Visible cues, but not masked cues, lead to shifts of attention. In Experiment 2, the arrow cues had an overall validity of 80%. Now both visible and masked arrows lead to shifts of attention. This is in line with findings that subliminal exogenous cues capture attention only in a top-down contingent manner, that is, when the cues fit the observer’s intentions

Change blindness: eradication of gestalt strategies

Arrays of eight, texture-defined rectangles were used as stimuli in a one-shot change blindness (CB) task where there was a 50% chance that one rectangle would change orientation between two successive presentations separated by an interval. CB was eliminated by cueing the target rectangle in the first stimulus, reduced by cueing in the interval and unaffected by cueing in the second presentation. This supports the idea that a representation was formed that persisted through the interval before being 'overwritten' by the second presentation (Landman et al, 2003 Vision Research 43149–164]. Another possibility is that participants used some kind of grouping or Gestalt strategy. To test this we changed the spatial position of the rectangles in the second presentation by shifting them along imaginary spokes (by ±1 degree) emanating from the central fixation point. There was no significant difference seen in performance between this and the standard task [F(1,4)=2.565, p=0.185]. This may suggest two things: (i) Gestalt grouping is not used as a strategy in these tasks, and (ii) it gives further weight to the argument that objects may be stored and retrieved from a pre-attentional store during this task

From Eyes to Minds: Perceiving Perception, and Attending to Attention

The most important visual stimuli that we encounter in everyday life may be other people, and in particular their eyes. We constantly monitor (and follow) where others are looking, and hundreds of studies have stressed the importance of eyes as uniquely powerful visual stimuli. This dissertation argues otherwise: The eyes are special only insofar as they signal deeper properties about the minds behind them—namely the nature and direction of others’ attention and intentions. We empirically support this view in two ways: First, in studies of ‘minds without eyes’, we demonstrate how well-known gaze effects (such as prioritized processing of eye contact in the ‘stare in the crowd’) readily replicate without any eyes at all, when the direction of attention and intention is signified in other ways. Second, in studies of ‘eyes without minds’, we demonstrate that such gaze effects are reduced when the eyes do not signal any underlying pattern of attention and intentions, even though they clearly look like eyes, as in the phenomenon we have dubbed ‘gaze deflection’. Finally, in a study of what we call ‘unconscious pupillometry,’ we also explore how the visual system automatically and unconsciously prioritizes others’ degree of attention (vs. distraction). Ultimately, what matters is not just perceiving and attending to the relevant physical features, but rather perceiving perception, and attending to attention. Collectively, this work shows how seemingly reflexive visual processes can be surprisingly sophisticated, and how visual processing may extract not only physical attributes, but also mental states

Automatic motor activation in the executive control of action

Although executive control and automatic behavior have often been considered separate and distinct processes, there is strong emerging and convergent evidence that they may in fact be intricately interlinked. In this review, we draw together evidence showing that visual stimuli cause automatic and unconscious motor activation, and how this in turn has implications for executive control. We discuss object affordances, alien limb syndrome, the visual grasp reflex, subliminal priming, and subliminal triggering of attentional orienting. Consideration of these findings suggests automatic motor activation might form an intrinsic part of all behavior, rather than being categorically different from voluntary actions

Spontaneous mindreading: a problem for the two-systems account

According to the two-systems account of mindreading, our mature perspective-taking abilities are subserved by two distinct mindreading systems: a fast but inflexible, “implicit” system, and a flexible but slow “explicit” one. However, the currently available evidence on adult perspective-taking does not support this account. Specifically, both Level-1 and Level-2 perspective-taking show a combination of efficiency and flexibility that is deeply inconsistent with the two-systems architecture. This inconsistency also turns out to have serious consequences for the two-systems framework as a whole, both as an account of our mature mindreading abilities and of the development of those abilities. What emerges from this critique is a conception of context-sensitive, spontaneous mindreading that may provide insight into how mindreading functions in complex social environments. This in turn offers a bulwark against skepticism about the role of mindreading in everyday social cognition

Enhanced subliminal emotional responses to dynamic facial expressions

Emotional processing without conscious awareness plays an important role in human social interaction. Several behavioral studies reported that subliminal presentation of photographs of emotional facial expressions induces unconscious emotional processing. However, it was difficult to elicit strong and robust effects using this method. We hypothesized that dynamic presentations of facial expressions would enhance subliminal emotional effects and tested this hypothesis with two experiments. Fearful or happy facial expressions were presented dynamically or statically in either the left or the right visual field for 20 (Experiment 1) and 30 (Experiment 2) ms. Nonsense target ideographs were then presented, and participants reported their preference for them. The results consistently showed that dynamic presentations of emotional facial expressions induced more evident emotional biases toward subsequent targets than did static ones. These results indicate that dynamic presentations of emotional facial expressions induce more evident unconscious emotional processing

Overt orienting of spatial attention and corticospinal excitability during action observation are unrelated

Observing moving body parts can automatically activate topographically corresponding motor representations in the primary motor cortex (M1), the so-called direct matching. Novel neurophysiological findings from social contexts are nonetheless proving that this process is not automatic as previously thought. The motor system can flexibly shift from imitative to incongruent motor preparation, when requested by a social gesture. In the present study we aim to bring an increase in the literature by assessing whether and how diverting overt spatial attention might affect motor preparation in contexts requiring interactive responses from the onlooker. Experiment 1 shows that overt attention-although anchored to an observed biological movement-can be captured by a target object as soon as a social request for it becomes evident. Experiment 2 reveals that the appearance of a short-lasting red dot in the contralateral space can divert attention from the target, but not from the biological movement. Nevertheless, transcranial magnetic stimulation (TMS) over M1 combined with electromyography (EMG) recordings (Experiment 3) indicates that attentional interference reduces corticospinal excitability related to the observed movement, but not motor preparation for a complementary action on the target. This work provides evidence that social motor preparation is impermeable to attentional interference and that a double dissociation is present between overt orienting of spatial attention and neurophysiological markers of action observation

A Motivational Determinant of Facial Emotion Recognition : Regulatory Focus Affects Recognition of Emotions in Faces

Funding: The research was supported by The Netherlands Organization for Scientific Research (NWO, project 452-07-006). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.Peer reviewedPublisher PD