16 September 2007

Say cheese! Or, evidence that facial muscles are the puppet-strings of the soul

Souls will come up regularly in this blog, for lots of reasons. For one, disembodied spirits (wandering souls, I presume) are everywhere in Shakespeare, and his very conception of death seems to be the separation of the soul from the body. I can't very well bring up Shakespeare without conjuring ghosts or visions thereof. Such visions are utterly commonplace in Western literature and thought, and Shakespeare certainly didn't cook them up (I recall spirits fluttering out of dead warriors in the Iliad, and that little piece of work was conceived just a few millenia before the Bard). The picture of someone "giving up the ghost" (hilariously pictured in "Who Framed Roger Rabbit?", if you remember that little gem) obviously inspires Romeo:

Now, Tybalt, take the villain back again
That late thou gav’st me; for Mercutio’s soul
Is but a little way above our heads,
Staying for thine to keep him company:
Either thou, or I, or both, must go with him.

--Romeo and Juliet, Act III, Scene I (The Oxford Shakespeare)
We need souls in our poetry, even when our poetry has no soul. Hamlet without souls? No such thing.

And of course, we need souls in Christianity. We're essentially dualists, meaning that we believe in everlasting souls encamped (or entrapped) in mortal bodies. Right?

Well, actually, no. I'm just a biologist, but some of my best friends are philosophers, Christian philosophers, and darn good ones at that. It's a story for another time, but suffice it to say for now that many hard-thinking Christians are advancing a physicalistic (or "materialistic") view of human persons, some while claiming that biblical evidence for belief in immaterial souls is quite thin.

But whether or not you're an agnostic on immaterial souls, you should find the notion of "embodied emotion" interesting, because:
  • It's cool science, and of course you love cool science;
  • You're a human, and humans, it seems to me, are dualistically inclined;
  • Souls are linked to various cognitive phenomena, including emotion;
  • You're reading a blog called Quintessence of Dust, for heaven's sake.
The 18 May 2007 issue of Science features a "Behavioral Science" theme, and includes a brief review of some new applications of theories of embodied cognition to the study of human emotion. The author, Paula M. Niedenthal, contrasts such theories with traditional models of human cognition built around the image of brains (and minds) as computers, and identifies the following assertion as distinctive of theories of embodied cognition:
...that high-level cognitive processes (such as thought and language) use partial reactivations of states in sensory, motor, and affective systems to do their jobs. Put another way, the grounding for knowledge -- what it refers to -- is the original neural state that occurred when the information was initially acquired. If this is true, then using knowledge is a lot like reliving past experience in at least some (and sometimes all) of its sensory, motor, and affective modalities.
The idea, then, is that when you think, you are in some ways reenacting the scenario or the information itself. You are thinking with your whole body, not just with the meat-based computational soul-center in your skull. (As cool as that thing is.) If you are, like I am, a fan of Antonio Damasio and his ideas, then you're already familiar with this type of thinking and theorizing, and with the connection he makes between emotion and consciousness.

So...body is connected with emotion, emotion with cognition...doesn't this mean, then, that your body -- muscles, bones, tendons, mundane animal machinery -- can influence, even control, your cognition? Hello, Professor Descartes? If you just smile, can that make you happy?

Well, consider some of the wild stuff in this article. In one experiment, subjects were registering their perception of a projected image by moving a lever. When they saw the image, they were to quickly move the lever. The participants surely thought the experiment was measuring their reaction time, and they were partially correct. But they probably couldn't have discerned the variable of interest: whether the lever was pulled, toward the body, or pushed away. In the experiment, images were flashed, some that would be emotionally positive, some negative. Subjects who were pushing the lever away responded more quickly to negative images, and vice versa.

Maybe I'm the only one, but that kind of thing really messes with my dualistic impulses. (And I'm not a body-soul dualist.) But there's more. The author describes some of her group's work, in which activity in 4 facial muscles was recorded while subjects were judging the emotional content of certain words. Here's her synopsis of the results:
...individuals embodied the relevant, discrete emotion as indicated by their facial expressions...in the very brief time it took participants to decide that a "slug" was related to an emotion (less than 3 seconds), they expressed disgust on their faces.
The author also describes the elegant control experiment: the subjects looked at the words in print and determined whether they were written in all caps. No such embodiment was detected in the facial muscle recordings.

You might think, "gee, it must take a lot of time to do all that embodying work when making decisions." You'd be right: the author describes experiments that show timing costs associated with switching systems (or modalities):
They are slower to verify that a "bomb" can be "loud" when they have just confirmed that a "lemon" can be "tart" than compared to when, for example, they have just confirmed that "leaves" can be "rustling."
And you might wonder whether we could alter your emotional state by forcing you to embody a particular state. Suppose we force you to smile; will this make you happier? Call me silly, but my initial response to this hypothesis is to scoff. But wait: inspired scientists are testing hypotheses very much like this one.

In the last experiment described by Prof. Niedenthal, each subject was asked to determine whether a sentence described something pleasant or unpleasant, while holding a pen in his or her mouth. Huh? Have a look at Figure 1 (you don't need a subscription to Science): holding a pen with the lips precludes smiling, and even seems to embody the opposite; holding a pen with the teeth forces the lips into a smile. I suppose you know what's coming:
Reading times for understanding sentences describing pleasant events were faster when participants were smiling...sentences that described unpleasant events were understood faster when participants were prevented from smiling.
"Smile and laughter comes thereafter." Pretty corny stuff; it can still make me faintly nauseous (another embodied emotion, clearly). But maybe it's true. And if the eyes are the windows of the soul, what does that make the jaw muscles?

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