My Current Views and Directions in Psychology

Body Representation:

The topic in psychology with which I am most engaged at the moment is that of body representation. This is essentially the question of how the brain constructs its internal representation of the body in which it resides, controls, and has the peculiar phenomenology of ownership for. This is a highly nuanced question that encroaches on issues previously relegated to the realm of armchair philosophy. One example is the distinction between self and other implicit in the generating of the body representation. Another is the aspect of self-consciousness that emerges from consciousness of one’s body. The nearest one can get to the scientific study of this issue is through the rubber hand illusion. This is an intriguing phenomenon that occurs when the brain is fooled into misattributing a rubber hand to itself through clever setups where the false hand is placed in a position congruent to the real hand and where both are touched synchronously, with only the touch on the rubber hand being visible.

Another avenue of interesting work in this field is the experimental induction of out of body experiences, pioneered by Henrik Ehrrson and colleagues at the Karolinska Institute in Denmark. This occurs using a clever manipulation of altered reality systems where the cameras were mounted behind seated participants and their image was displayed on a head-mounted display that allowed the subjects binocular vision of themselves from behind. They were then touched on the chest by the experimenter, who was careful to prevent them vision of this, while simultaneously hovering a ruler under the cameras in clear vision of the subjects. This is effectively a whole-body generalization of the rubber hand illusion, and is said to produce a similar phenomenology of body dissociation and misattribution. 

These methods provide an experimental method to probe the mechanisms of body representation and, in particular, the malfunctioning or the erroneous functioning, of this system. That it is possible for the brain to perceive a rubber hand as part of itself despite the rebellion of the cognitive system’s clear knowledge that this cannot be is a truly remarkable fact. It is a triumph of bottom-up over top-down, where the discursive and reflective parts of the brain are issuing down the results of their evaluation that arrive insignificantly to the perceptual apparatus of the brain that continues to maintain its illusory self-attribution of the patently false arm. In studying the conditions that give rise to this phenomenon, we can hope to attain an understanding, at least a rough one, of how the brain comes to generate its representation of the body it inhabits. So far as we can currently tell, this illusory perception results from what Ramachandran calls the “Bayesian logic” of the brain, which is an inferential process that attempts to create an internal representation of the world and all sensible objects therein, in this case the body, via a causal inference that operates on the sensory signals that impinge on the body. If these signals are correlated in just the right ways – that is, in ways likely to have been generated by the same object – then the brain creates an object from which these sensory signals originate. And, all objects which give rise to tactile signals must be part of the body; this in the Bayesian framework would be called the ‘prior’, an assumption or constraint that the brain implements.

Consciousness:

Another phenomenon that I am deeply fascinated by is consciousness. Arthur Schopenhauer speaks of this phenomenon as ‘the necessary correlate’ of the world, which whomever possesses powerful enough reflective capacities would be able to realize as the fundamental carrier and supporter of the whole of perceptual reality. I share a similar conviction with him and recognize the enormous importance and generality of this concept. It is one of the most universal concepts – second only to existence itself, if this latter isn’t also subsumed within it, which it arguably is. As Plato instructs us in the practice of philosophy to search for the general in the particular, our abstracting mind cannot find anything under which to subsume the concept of consciousness, and this is so precisely because of its fundamental nature as that which conditions the whole world of empirical reality as observed.

All this fluffy philosophical talk aside, there has recently been a tremendous amount of effort and research directed towards the scientific study of this ephemeral topic. Theories abound and every cognitive researcher worth his buck has a pet theory, whether it is framed in neural, cognitive, or information theoretic terms. Alongside this profuse theorizing are ingenious experimental designs that allow us to actually study mechanisms that give rise to phenomenal consciousness. Some search for the neural correlate of consciousness (NCC) while others look for neural signatures of changes in its content, and others take different approaches.

My current favorite theory of consciousness is Bernard Baars’ “Global Workspace Theory”. This offers an intuitive way to think about the various notions that float around psychology circles such as attention, working memory, ‘binding problem’ in perception, and not least of all, consciousness. The essential premise of the theory is that various information processing modules in the brain that operate independently and unconsciously compete in order to transmit the output of their processes into the working memory module, success of which leads to those outputs being globally broadcast to the whole brain in order to recruit processing from unrelated modules, such as speech for reportability, motor function for incorporation into volitional strategies, perhaps multimodal areas for binding of percepts, etc. On this account, consciousness is just whatever activity has made it into the working memory as well as being globally broadcast. I am not yet 100% satisfied by this account however. It seems to address the question by means of offering a sort of network framework; in other words, it is answering the ‘easy problem’ but does not seem to tackle the ‘hard problem’ at all. The former of these deals with how brain activity gives rise to ‘access consciousness’, that which can be used by the rest of the brain, whereas the latter concerns itself with ‘phenomenal consciousness’, that which forms the qualitative feel of experience – what philosophers call ‘qualia’. So, while Baars’ theory may satisfactorily give a mechanistic account of the processing that takes place in the brain that gives rise to an integrated network of information, it seems to dodge the deeper question of why this particular form of processing is accompanied by awareness, that ephemeral ‘knowing’ of which we cannot really speak, which remains here unaddressed. Of course, I run the risk of blaspheming against the current ideology of the material metaphysic that dominates most modern intellectual thought. Nevertheless, I do so from an intuition of the inadequacy of naturalist science. Whether or not the hard problem is even solvable in principle I cannot say. Yet still, I maintain that the acknowledgement of this problem mandates a radically revised ontology.

I must insert here, despite what has been said above, the fact that I am gradually beginning to lean towards a more eliminitavist position on the ‘hard problem’ debate. That is to say, I do have moments of skepticism towards these so-called ‘intuitive’ accounts that postulate the existence of a hard problem. It may be that the workspace account exhausts all there is to consciousness and that it is precisely the integration of a percept into the global workspace that brings about this phenomenal experience of its ‘qualia’. Either deeper introspection or hard science may eventually elucidate this extremely subtle question, but for now it remains an utter mystery.

Attention:

This consideration brings me to another favorite topic of mine in neuroscience and psychology. This is the phenomenon that is colloquially as well as academically known as attention. At first glance, it may seem like there is a significant overlap, if not synonymy, between this concept and consciousness. However, closer scrutiny reveals that while the two are related, it remains advantageous to maintain a conceptual distinction between them. Attention can be thought of as the selective mechanism that decides which of the vast array of incoming sensations and internal operations are consciously experienced. In the workspace framework, it is the effect of the mechanisms that collectively determine which information processing module ‘wins’ the battle to relay its message into the working memory, which subsequently relays the message globally. As such, it is sometimes symbolized as a ‘spotlight’, which scans across the various actors and/or props on a theater stage, selecting as it does which of these is to become the center of focus for the audience. There may be a slight circularity in this metaphor, since attention is itself the mediator of its own symbol, but it suffices for the purposes of illustration.

Many theories have been proposed as to the functioning of this attentional spotlight, and there are several subdivisions of the concept that I will briefly go over here. First, attention is divided into top-down and bottom-up forms. The former, also known as endogenous attention, is the form of attention that is at play when we consciously select what to attend to on the basis of goal-directedness; hence, top-down. Bottom-up attention, conversely, is at play when some highly salient stimulus from the environment captures our attention and draws our processing resources to it, such as when you hear your name spoken and it seems to ‘pop’ into your awareness uninvited. So, while both are selection mechanisms, one operates in a purely automatic fashion based entirely on the perceptual saliency of stimuli, perhaps as an evolutionarily hard-coded adaptive system, whereas the other operates in a volitional fashion and is based on the goals and intentions of the agent.

An immediate question that arises regards the extent to which attention’s selective power can exclude distractors from reaching and interfering with the task that is being performed at the center of the ‘spotlight’. Nillie Lavie’s theory of perceptual load offers an elegant solution to this question. Her claim is that there are multiple factors that play a role in determining the selectivity of attention and its ability to protect against intrusion by task-irrelevant distractors. These are the so-called perceptual load and the working memory load. The effects of these are inversely proportional to each other, where loading the former exhausts perceptual capacity which hence cannot be used to process distractors, whereas loading the latter interferes with the brain’s ability to maintain current goals in order to exert its top-down attentional selection, hence causing greater intrusion by distractors. This account relies on the concept of perceptual resources, of which there may remain some that are not used in the processing of the central task, and which may ‘spill over’ and automatically process task-irrelevant stimuli. 

Another of my favorite subjects is meditation, and this is directly related to attention insomuch as it is an activity whose purpose is to train the attentional focus of the meditator’s brain. By so doing, it makes the selective function of attention stronger, causing more processing resources to be utilized in the processing of the central task. This may be because it frees up working memory capacity, which therefore will reduce the amount of distractor interference because of the availability of resources to effectively select stimuli. I have noticed from my meditations that the beginnings are usually characterized by an effusive scattering of my thoughts from one topic to the next and an extreme difficulty at keeping the attentional spotlight fixed on the object of the meditation, which in this case would be the breath. As the sit progresses, I am more and more able to filter out the competing distractors and keep the flame unwavering, and this may just be because of the freeing up of space in the working memory. Alternatively, it may also be because of the strengthening of mechanisms that bring the desired object into the working memory and the weakening of those same mechanisms for irrelevant objects. However, I currently favor the first account because it is more in line with the subjective experience of meditation where what is in the forefront of the ‘theater of the mind’ seems to become uncluttered. Another way to think about this is to posit that the non-meditator’s attention fluctuates between a variety of stimuli including the centrally relevant task as well as other interfering stimuli. In other words, many modules are ‘winning’ the battle to transmit their outputs to the working memory, and this causes the frequent distraction. The meditator, on the other hand, has more stringent selection criteria for the conditions under which outputs can be transmitted into the working memory. This may turn out to be the exact same situation that leads to the freeing up of the working memory capacity.

Directions:

By studying the body representation mechanisms of the brain, I hope to somehow be approaching the issue of self-representation, which in turn taps into the issue of self-consciousness. As it currently stands, I am only looking at a very specific perceptual phenomenon, namely the rubber hand illusion. Eventually, I hope to be able to examine how the consciousness of the illusory percept is generated. This may possibly account for why some participants do not experience the illusion, despite showing strong proprioceptive effects. Perhaps I can demonstrate some dissociation between dorsal and ventral streams in the processing of the illusion. Additionally, the effect of attention on the rubber hand illusion may prove to be something worth investigating. It may be that an attentional deficit is responsible for the failure to experience the illusory percept. Finally, if the holistic integrated percept of the body is generated through a process of causal inference, what additional constraints need to be implemented in order for the self/other discrimination that is fundamental to our sense of selfhood? The causal inference rules used here are the same that the brain uses to generate its perception of all impinging sensations, whether they originated from the body or otherwise. Therefore, there must be some additional rules that are instantiated in the specific case of body perception.

My current research simply aims to elucidate further the link between proprioceptive localization of the finger under conditions of visual occlusion and experience of the rubber hand illusion. Several recent studies have shown that proprioceptive drift may not in fact be a reliable behavioral proxy of the illusion and may simply occur as a natural result of visual occlusion. My research seems to tentatively support this idea, but the analysis that I will run on the data will hopefully reveal more than has been previously shown thanks to an additional manipulation that I am introducing. The goal of this is to eventually find a way to mathematically model the processes that are taking place in the brain when it is performing visual-proprioceptive integration, the hope being that a natural explanation for drift and bias will emerge from the equations. At a later stage, it may become possible to model the trimodal integration that takes place between vision, proprioception, and touch, the result of which is the rubber hand illusion. However, at the moment, this is an impossible task as there are too many free parameters and too few variables that can be reliably measured in order to constrain the model by fitting it to collected data. But science progresses step-by-step, and so I must remain patient and persistent in my attempts to arrive at clever designs that can answer some or all of the questions and issues discussed above.