Thinking about Libet, pt 2

In my last post, I briefly discussed the most pertinent results from Benjamin Libet’s 1982 experiment and some of the implications. In this post, I would like to put on my speculative hat and talk about an alternative to the dichotomy I set up in the previous post I linked.

If you don’t recall, the dichotomy was set up between what appears to happen when we hear a noise behind us and what Libet thought was going on. What seems to be going on is that we consciously hear a sound and then turn around, but Libet proposed that we unconsciously hear it first, turn around, and then our brain performs a “backwards subjective referral” of the event to make it seem like the first scenario is happening. In my last post I said this was a false dichotomy and now I will speculate on what I think is really going on. Bare with me.

Imagine that a human body is sitting in a classroom and attending to the lecturer. All of a sudden this attentive human becomes aware of a door opening behind his back and cocks his head around accordingly in order to see what just interrupted the lecture. All of this activity, including the awareness of the noise of the door opening and the innervation of the appropriate neck and back muscles, all happened within the more-or-less continuous, 3d perceptual space that we all are familiar with.

So, while there are hundreds of potential things to be attentive of in any normal classroom(including the awareness of your own body sitting down), the available cognitive processing power responsible for “shifting the attentional spotlight” allocated almost the entirety of its capacity to the perception of the door opening, probably because of the neural contrast/distinction of such a sudden noise but also because this human body knows from past experience that usually the only things that open doors are other humans and it is this implicit social knowledge imbedded into action-schemas that makes it hard not to notice sudden changes in the social environment.

This contextual social knowledge makes it obvious why more attentional capacity would be allocated to the perception of the door opening rather than say the perception of his body twisting around or the perception of practically anything else in the room, even though the overall body-system never stopped being aware of these things, it is just that the percentage of attentional capacity devoted to the door opening made that particular activity more vivid that anything else upon episodic recollection. With the situation set up in this way, let us try go back to explaining Libet’s half-second delay.

Under my conceptualization, the reason why the neural isomorphic representation of the door opening seems to “echo”(thanks Dennett) around the brain for an “extra” half second past the “necessary” evoked motor potentials is because the brain is essentially “telling a story to itself” about the event. The functionality of this generated “after-the-fact” story comes from the fact that the door-opening-event is now easily fed into a variety of different cognitive systems thanks to the considerably long(in brain terms) half-second of processing necessary to turn such “noisy” sensory data into higher-level “conceptual” representations that implicitly include such linguistic conceptual relativities as self/other, internal/external, etc. important for metaphor-based story telling.

Furthermore, I speculate that evolutionarily speaking, the most advantageous way of putting these high-level representations of low-level sensory-action-data to use would be through an advanced memory/prediction/empathy system. This interrelated triad would be of great advantage in a social atmosphere. Perhaps I will elaborate on this triad a later post, but for now I am done wildly speculating from my armchair.

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Thinking about Libet

In 1982, Benjamin Libet carried out a remarkable study on consciousness that is still being debated by contemporary philosophers and scientists. In today’s post I would like to briefly highlight the results and spell out some implications. Here are the most pertinent results as far as I can see them:

• In order to “consciously experience” a sensation, it must apparently bounce around the somatosensory cortex, or some other “high-level” area of the cortex for about half a second, probably isolated to the frontal areas(Libet, 1982)
• “A touch on the skin that the subjects would otherwise have reported feeling was retroactively masked up to half a second later by a stimulation to the cortex”(Blackmore, 2004)

Okay, so how can phenomenological consciousness “drag” half of a second behind the real world when clearly we are able to react much faster than that? The most obvious idea is to say that consciousness has no causal power, it is merely a resultant and not a force (in James’ terms). However, this is at odds with the “hard problem” of consciousness because if our “unconscious” does all the important work, such as reacting to dangerous stimuli in split-second situations, there would have been no evolutionary pressure for phenomenal consciousness to tag along and “dangle” half a second behind the real important things going on in the world, such as a stepping on a snake or braking for a red light.

I believe that I can sketch out a framework that can reasonably explain how consciousness could happen “after the fact”, yet still have enough function that it could easily have evolved in the way that it did given the close-knit social structures of our early hominid ancestors.

Let us look at Blackmore’s example of turning around to look who just opened a door while you are sitting in a classroom. This is what seems to happen:(from blackmore)

Scenario 1

1. Consciously hear sound
2. Turn around to look

According to Libet, it should be more like this:

Scenario 2

1. Unconsciously “hear” sound
2. Turn around to look
3. Backwards subjective referral of consciousness to make it seem like Scenario 1 is what actually happened

So how do we extricate ourselves from this mess? I think the first step is to recognize that you are setting up a false dichotomy of sorts by trying to directly reconcile scenarios 1 and 2 as the only two options. Furthermore, we should follow Dennett’s advice and use extreme conceptual caution when using the terms “conscious” and “unconscious”, because the nature of our language necessarily forces an implicit acceptance of the Cartesian Theater whenever we use the language of conscious/unconscious, and it is this intuitive dichotomy that makes it impossible to solve these kinds of philosophical problems using ordinary conceptual frameworks.

However, if we use the framework of enactive perception and attentional theories of consciousness, we will get a better understanding of why trying to decide between either Scenario 1 or 2 will only result in frustration and headaches. In my next post I will discuss an alternative way of looking at this problem. Stay tuned!

References
Libet, B. 1982 Brain Stimulation in the study of neuronal functions for conscious sensory experiences. Human Neurobiology 1, 235-42

Blackmore, S. 2004 Consciousness: An Introduction

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