I came across an article, “Perceptual Pleasure and the Brain,” by Irving Biederman and Edward Vessel in American Scientist. They studied the distribution of mu-opioid receptors, associated with the modulation of pleasure and pain, in the visual cortex. Their basic result: “The receptors are sparsest in the early stages of this [central visual] pathway, the so-called V1 to V4 areas, where an image is processed as local bits of contour, color and texture. Intermediate stages of visual processing, such as the lateral occipital area and ventral occipito-temporal cortex, which integrate local information to detect surfaces, objects, faces and places, contain greater number of opioid receptors. The receptors are densest in the later stages of recognition, in the parahippocampal cortex and rhinal cortex, where visual information engages our memories.”
Thus, they argue, “a visual stimulus that elicits many episodic or semantic memories should be more pleasing (or more interesting) than a stimulus that brings forth fewer mental associations.”
They back up this basic neurological argument with fMRI data: “As our theory predicts, scenes that were rated highly [in preference] elicited the most fMRI activity in the parahippocampal cortex, especially the posterior portion. The activity in this area was not the result of a simple ‘feed forward’ mechanism, because a region involved in early processing of visual information, the lateral occipital area, showed its greatest activity when the subject was viewing scenes of low preference.”
I find this article striking for four inter-related reasons. First, in addictions research, you hear so much about pleasure “centers” or “hotspots,” arguments that pleasure and pain are localized into specific areas. Here the research shows that “reward” can be involved in some basic processing. Preference is not added in later, like some rational utility ranking—it is part and parcel of what the visual system is doing.
Second, I find it comforting somehow when brain research confirms basic things, that gazing on an ocean scene is a thing-in-itself that we enjoy. Put differently, I see this research as highlighting the importance of a phenomenological approach. Experience matters. In an often challenging scholarly environment that wants to wash the subjective out, research like this provides a validity that goes beyond simple assertion.
Third, the authors emphasize the importance of connections, interpretations, memory, and novelty. “We wish to emphasize the perceptual preferences arise from the connections the brain makes with stored information. That’s because the brain’s association areas have the greatest density of mu-opioid receptors. In other words, it is the interpretation of a visual pattern that leads to the feelings of pleasure.” This perspective opens up vistas for interpretative approaches in anthropology, to go beyond symbolism as a thing outside of people to something that gets embodied and enacted through and with people.
Finally, these points led us closer to what Greg has continually emphasized in this blog. As he wrote about language and color, it is not “language” that causes the difference in perceptions, but a more open approach that emphasizes practice and use. To paraphrase him, people using their visual systems get lots of practice making perceptual distinctions. There is no need to link to an abstraction, such as “pleasure” or “symbolism” or “evolution,” but to enter into the gazing itself, the study of a painting or a lover’s face.
American Scientist Article Link: http://www.americanscientist.org/template/AssetDetail/assetid/50770#51025
Irving Biederman Page: http://geon.usc.edu/~biederman/
Edward Vessel Page: http://www.cns.nyu.edu/~vessel/