Emotion’s role in the unity of consciousness

ABSTRACT

In subjects with the split-brain syndrome, some conscious states appear to be disunified (e.g., visual states), while others remain unified (e.g., affective states). While placing emphasis on the disunities, disunity accounts conclude that split-brain subjects have two subjective perspectives and not one. I argue that affective unity is more important than perceptual disunity in delineating our subjective perspective. Unlike enjoying an objective perspective, enjoying a subjective perspective entails experiencing aspects of your phenomenal field in terms of their overall relation to you. What it’s like to be you at any given time entails experiencing certain aspects of the phenomenal field as peripheral to others. Emotion creates and sustains a center/periphery structure in our phenomenal field by signaling orders of perceived importance as well as orders of perceived changeability (e.g., to someone feeling grief, the experience of getting a ticket is felt as peripheral/unimportant to the experience of grief; to someone feeling depressed, the experience of reaching a hilltop is felt as peripheral/unattainable to the experience of laying down to rest). Since emotion plays a greater role than perception in creating and sustaining this periphery/center structure, and split-brain patients remain affectively unified, split-brain patients retain a unified subjective perspective on the world.

KEYWORDS:

• Unity of consciousness
• split-brain syndrome
• phenomenal consciousness
• access consciousness
• emotion
• perception
• agency

Acknowledgments

Special thanks to Elizabeth Schechter for reading countless drafts of this work. Also heartfelt thanks to anonymous reviewers and conference commentators for helpful feedback.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Notes

1. Bayne (2010) and others write that “the split-brain procedure has surprisingly little impact on cognitive function in everyday life. Split-brain patients can drive, hold down jobs, and carry out routine day to day tasks. Early researchers remarked on their “social ordinariness,” and were baffled by their inability to detect any cognitive impairments arising from the operation.Dahlia W. Zaidel, “AView of the World from a Split-Brain Perspective,” in E.M.R. Critchley, ed., The Neurological Boundaries of Reality (Northvale, NJ), pp. 161–74; S.M. Fergusen et al., “Neuropsychiatric Observation on Behavioral Consequences of Corpus Callosum Section for Seizure Control,” in A.G. Reeves, ed., Epilepsy and the Corpus Callosum, pp. 501–14. But see also Victor Mark, “Conflicting Communicative Behavior in a Split-Brain Patient: Support for Dual Consciousness,” in S.R. Hameroff et al., eds., Toward a Science of Consciousness (Cambridge: MIT, 1996), pp. 189–96.

2. Ellenberg and Sperry (1979) The Syndorme of hemisphere deconnection. Dahlia W. Zaidel, “AView of the World from a Split-Brain Perspective,” in E.M.R. Critchley, ed., The Neurological Boundaries of Reality (Northvale, NJ: Aronson, 1995).

3. Schechter (2018)

4. Left hemisphere is in control of speech, whereas the right hemisphere controls the left hand. Carlson, (2004). Physiology of Behavior, 6th Ed. The received view has been that visual information projected to the right visual field cannot be verbally reported, and visual information projected to the LVF is unavailable for behavior involving the right hand (Bayne, 2010). However, recent findings by Pinto et al. (2017) show that split-brain patients can indeed respond accurately to stimuli appearing anywhere in the visual field using any response modality (e.g., using speech, right, and left hand). I save the discussion of these results for later in the paper.

5. I use the terms “subjective perspective” and “point of view” interchangeably.

6. At the very low level, the limits of an action event are delineated by affect (Muhle-Karbe & Krebs, 2012). According to the theory of event coding (Hommel et al., 2001), various perceptual elements are part of the same event if they are represented in the same event code. This theory explains interactions between products of perceptual processes and the first steps of action planning (Eder & Klauer, 2007). Theory of event coding states that perceived features of objects and planned features of motor actions are cognitively represented through structurally identical “event codes”. Because of this common code, stimulus and action features can prime one another (Beckers et al.’s, 2002; Elsner & Hommel, 2001). The main outcome of this binding is action-effect blindness. That is, codes that are already in use cannot be accessed for further use. The common code assumption or the fact that coding of percepts and actions relies on identical format of representations is supported by findings on selective impairments. Using the same model of code overlap, researchers proposed the affective coding hypothesis to demonstrate how event files are organized by affect. Specifically, affectively charged action plans (e.g., saying ‘‘good’’ or ‘‘bad’’) impair simultaneous evaluations of stimuli with the same valence (Eder & Klauer, 2007) Furthermore, the single feature valence code irrevocably activates the entire event file (Hommel & Musseler, 2006; Müsseler & Hommel, 1997a, 1997b)”. Similarly, Eder et al. (2012) demonstrated that preparing a button press that signals the affective value of a picture delayed the performance of an affectively congruent approach and avoidance movement simply because that concurrent processes was utilizing the same affective code.

7. Since some emotional states are cognitively penetrable, this seems like a reasonable hypothesis. Karl Lange and William James have theorized that bodily changes associated with emotional episodes precede the feeling of emotion itself. They explain examples of emotional episodes such as fear by pointing to the bodily accompaniments of such episodes (e.g., sweaty palms, increased heart rate, dry mouth). They hypothesized that emotions simply are neocortical “readouts” of bodily autonomic arousals (Cannon, 1927)

8. Here I replace “percepts” used in the original quote with “emotions”.

9. In particular, while Bayne and Chalmers argue that enjoying a unified phenomenal perspective entails experiencing all phenomenal states as merely co-conscious, I argue that enjoying a unified phenomenal perspective entails experiencing aspects of your phenomenal field in orders of perceived importance and perceived changeability. Since affective states allow us to experience aspects of our phenomenal field via orders of perceived importance and orders of perceived changeability, affective phenomenology is not just another phenomenal state in the unstructured phenomenal field. Since affect plays a special role in ensuring a unified subjective perspective, unified affect in the split-brain is enough to ensure a unified subjective perspective on the world.

10. Transcranial magnetic stimulation (TMS) is a type of targeted brain stimulation induced by a changing magnetic field (e.g., Killgore & Yurgelun-Todd, 2004)