A theory of consciousness

Consciousness is the subjective awareness of momentary experience interpreted in the context of personal memory and present state. I propose that two brain systems converge to create consciousness. The exogenous system sends information about multimodal external stimuli to basal dendrites in widely dispersed pyramidal cell ensembles in the cortex of the brain; this system produces synchronized fragments of sensations. The endogenous system distributes readout of representations of memories, activated in systems established by associative learning, diffusely to apical dendrites. Convergence of exogenous and endogenous inputs enhances cellular excitability, and fragmented sensations are thereby converted to fragments of perception. Local field potentials periodically modulate all cortical membrane potentials and facilitate synchronous discharge of these excited elements. Feedback between the cortex and the thalamus results in a cortico-thalamo-cortical reverberation, binding the fragments into a unified global percept. Sustained reverberation produces a resonating electromagnetic field of synchronized elements. The momentary content of information in the brain is this distributed coherence, which is negative entropy. Consciousness is a physical property of this field, producing the subjective awareness of this information.     

Consciousness as a Process: From the Loneliness of William James to the Buzzing and Booming Voices of Contemporary Science

This Special Issue of IPBS brings the old metaphor of William James—consciousness as a “stream of thought”—to a contemporary critical inspection. It is demonstrated—based on materials of language (Panksepp 2008; Shanahan 2008), perception (Engelmann 2008) and dialogical self (Bertau 2008) that the classic river metaphor is an inadequate depiction of the multi-level psychological processes that are regulated by the affective systems of the brain and hierarchically integrated through dialogical and semiotic mechanisms.

The effects of expectancy on inhibition of return

This research examined the influence of cue temporal predictability on inhibition of return (IOR). In exogenous attention experiments, the cue that summons attention is non-informative as to where the target will appear. However, it is predictive as to when it will appear. Because in most experiments there are equal numbers of trials for each cue-target interval (SOA--stimulus onset asynchrony), as time passes from the appearance of the cue, the probability of target presentation increases. Predictability was manipulated by using three SOA distributions: non-aging, aging and accelerated-aging. A robust IOR was found that was not modulated by temporal information within a trial. These results show that reflexive effects are relatively protected against modulation by higher volitional processes.     

Hemispheric asymmetries for temporal information processing: transient detection versus sustained monitoring

This study investigated functional differences in the processing of visual temporal information between the left and right hemispheres (LH and RH). Participants indicated whether or not a checkerboard pattern contained a temporal gap lasting between 10 and 40 ms. When the stimulus contained a temporal signal (i.e. a gap), responses were more accurate for the right visual field-left hemisphere (RVF-LH) than for the left visual field-right hemisphere (LVF-RH). This RVF-LH advantage was larger for the shorter gap durations (Experiments 1 and 2), suggesting that the LH has finer temporal resolution than the RH, and is efficient for transient detection. In contrast, for noise trials (i.e. trial without temporal signals), there was a LVF-RH advantage. This LVF-RH advantage was observed when the entire stimulus duration was long (240 ms, Experiment 1), but was eliminated when the duration was short (120 ms, Experiment 2). In Experiment 3, where the gap was placed toward the end of the stimulus presentation, a LVF-RH advantage was found for noise trials whereas the RVF-LH advantage was eliminated for signal trials. It is likely that participants needed to monitor the stimulus for a longer period of time when the gap was absent (i.e. noise trials) or was placed toward the end of the presentation. The RH may therefore be more efficient in the sustained monitoring of visual temporal information whereas the LH is more efficient for transient detection.     

The impact of eye contact on the sense of agency

Recent research suggests that eye contact can lead to enhanced self-awareness. A related phenomenon, the sense of agency deals with the notion of the self as the origin of our actions. Possible links between eye contact and agency have been so far neglected. Here, we investigated whether an implicit sense of agency could be modulated by eye gaze. We asked participants to respond (button press) to a face stimulus: looking or not at the participant (experiment 1); or displaying distinct eye gaze before or after a mask (experiment 2). After each trial, participants estimated the time between their key press and the ensuing effects. We found enhanced intentional binding for conditions that involved direct compared to averted gaze. This study supports the idea that eye contact is an important cue that affects complex cognitive processes and suggests that modulating self-processing can impact the sense of agency.     

Environmental control and psychosis-relevant traits modulate the prospective sense of agency in non-clinical individuals

The sense of agency concerns the experience of being the source of one’s own actions and their consequences. An altered sense of agency can occur due to task automation and in psychosis. We tested in a non-clinical sample the hypothesis that reducing voluntary task control diminishes intentional binding as an implicit indicator of the sense of agency, possibly interacting with psychosis-relevant personality traits. Agent-device interactions were manipulated obtaining positive-control (voluntary interaction), no-control (automation), and negative-control (device-commanded interaction) groups. The main results showed reduced prospective intentional binding (predictive coding of action consequences) in the no-control and negative-control groups, compared to the positive-control group. Psychosis-like experiences covaried positively with intentional binding in the no-control group, but negatively in the negative-control group. Moreover, positive-social traits were associated with increased intentional binding in the positive-control group. These findings demonstrate the interplay between environmental and individual differences variables in establishing the implicit sense of agency.     

Compress global,dilate local: Intentional binding in action–outcome alternations

Intentional binding refers to subjective temporal attraction between an action and its outcome. However, the nature of intentional binding in multiple actions remains unclear. We examined intentional binding in alternated action–outcome dyads. Participants actively or passively pressed a key, followed by a tone, and they again pressed the key; resulting in four keypress–tone dyads in a trial. Participants reproduced the duration of alternated keypress–tone dyads or the temporal interval between a dyad embedded in the alternations. The reproduced duration was shorter in the active than in the passive condition, suggesting the intentional binding in action–outcome alternations. In contrast, the reproduced interval between a dyad was longer in the active condition and did not correlate with the reproduced duration. These results suggest that subjective time during actions relies not only on an internal clock but also on postdictive biases that are switched based on what we recall.     

Social exclusion reduces the sense of agency: Evidence from intentional binding

Social exclusion is known to induce an immediate threat to one’s perceived sense of control. The sense of agency is an important human experience, strongly associated with volitional action. Healthy participants perceive the temporal interval between a voluntary action and its effect to be shorter than the same interval when it separates an involuntary action and effect. This temporal illusion is known as intentional binding and is used experimentally to index the implicit sense of agency. The current study investigated whether activating memories of social exclusion alters intentional binding. Results show that action-effect interval estimates are significantly longer after remembering an episode of social exclusion than after remembering an episode of social inclusion, or a no priming baseline condition. This study is the first to demonstrate the link between feelings of social exclusion and the pre-reflective sense of agency.