Entry tags:

autism, my research

Eye Contact & Evolution
Okay, so I'm kind of stealing this post from my Case Study on Gestalt. I may consider suing myself at some point for copyright violation. But for now, I'll simply push blindly and brazenly ahead in spite of any of my protests.

A recent post on Gestalt made me think about eye contact in autism:

In an evolutionary sense, the eyes hold a considerable amount of information. They are vital communicative tools and have the potential to produce a great amount of anxiety in the gaze-receiver. In many mammals, direct gaze can be an aggressive gesture, including in humans (although with the intricate subtleties of our nonverbal language, direct gaze can mean far more than just aggression). And even in some of the least social animals, they are still cognitively capable of identifying the eyes of an unrelated species. Ever noticed how your pets are capable of knowing precisely where and what your eyes are? They know when you're watching them and when you're not. And when you think about it, that's an incredibly complex neural template to be generated. It means that, for the most part, any unfamiliar animal you-- or your pet-- come across, you have a schema for "eyes" despite that you've never seen that creature before. In predator/prey species which usually involve hunting, chase, and capture, the eyes are vital to survival. The predator needs to know when the prey isn't looking at it, so that it can better take the animal unaware. The prey also needs to know when the predator is looking at it, when it is likely to charge, where the predator's attention is, etc. In social species, the eyes are even more important, providing an additional tool for communication and cementing social bonds.

So, eyes for many animals are fraught with potential anxiety. This is true for humans (notice how in some cultures, eye contact tends to be avoided more often with strangers than with familiars). Therefore, it should also be true for autistics. And since we autistics tend to take anxiety to an extreme, it makes some sense that we might take anxiety produced by eye contact to a greater extreme than our nonautistic counterparts.

Even within the autistic spectrum there is a spectrum of eye-anxiety. Some autistics have such extreme anxiety provoked by eye-to-eye contact that they avoid looking at the face altogether. Others have anxiety to a lesser extent and may be able to look somewhere on the face or make briefer glances at the eyes. Others may have overcompensated for lack of eye contact and take their correction to the extreme and make too much eye contact. And still others, I'm sure, have fairly average amounts of eye contact. Like I said, we're a spectrum where eye-anxiety may be more likely but is not a prerequisite for diagnosis.

For those individuals (myself included) who are capable of making general "face contact" but still find the eyes a bit too overwhelming or distracting, "mouth contact" may be an alternate gaze point. In my experience, humans are extremely sensitive to variations in horizontal (side-to-side) gaze but not in vertical (up-and-down) gaze. So if one were to look at the mouth rather than the eyes, which are in direct vertical line with one another, then most people can't tell that true eye contact isn't being made. Only until the vertical gaze variation is more extreme can someone tell; for instance, if I'm talking with someone and they're just a few inches from my face.

Autistics do seem, on average, to exhibit more "mouth contact" than nonautistics, as shown by eye-tracking technology. One study by Ami Klin et al. (2002) reported:

"Consistent with our predictions, individuals with autism focused 2 times more on the mouth region, 2 times less on the eye region, 2 times more on the body region, and 2 times more on the object region relative to age- and verbal IQ-matched controls. Effect size was greatest for fixation on the eye region, making it the best predictor of group membership. [...]

"We next explored the association between fixation time measures and measures of social competence. Contrary to our expectation, fixation time on the eye region was not associated with either social adaptation (VABS-E socialization scores) or social disability (ADOS social scores) [...] In contrast, fixation times on the mouth region and on the object region were strong predictors of social competence, albeit in different directions. Fixation time on the mouth region was associated with greater social adaptation (ie, more socially able) and lower autistic social impairment (ie, less socially disabled). Going in the opposite direction, fixation time on the object region was associated with lower social adaptation and greater autistic social impairment" (pp. 812-813).

One possibility is that those autistics who showed little "mouth contact" simply found the eye region too overwhelming altogether and were therefore reduced to looking more at objects, while those who looked at the mouths had less eye anxiety and so were able to focus in on the mouth more. The level of eye anxiety could be directly related to severity of the autistic phenotype: the more extreme the expression of autism, the more severe the anxiety provoked by eye contact. And also usually the more severe the expression, the less socially able an autistic is.

There's a lot of information in the eyes. It's hard to tell just how much a lack of eye contact detracts from social fluidity. Surely it plays some role, although how large is hard to tell. I.e., how much is lack of eye contact a direct cause of social difficulties and how much of it is simply correlated to the level of phenotypic severity?

In any case, having been on these online forums since 2004, it's obvious to me that many autistics have a difficult time with anxiety produced by eye contact, so much that we frequently avoid it to varying degrees. And, interestingly, the neural substrates that underlie this tendency are probably not new to autism, but can be found throughout primate evolution and resonate as far back as the early predator-prey terrestrial hunting relationships.