The notion of “the aesthetic” is a concept from the philosophy of art of the 18th century according to which the perception of beauty occurs by means of a special process distinct from the appraisal of ordinary objects. Hence, our appreciation of a sublime painting is presumed to be cognitively distinct from our appreciation of, say, an apple. The field of “neuroaesthetics” has adopted this distinction between art and non-art objects by seeking to identify brain areas that specifically mediate the aesthetic appreciation of artworks.
However, studies from neuroscience and evolutionary biology challenge this separation of art from non-art. Human neuroimaging studies have convincingly shown that the brain areas involved in aesthetic responses to artworks overlap with those that mediate the appraisal of objects of evolutionary importance, such as the desirability of foods or the attractiveness of potential mates. Hence, it is unlikely that there are brain systems specific to the appreciation of artworks; instead there are general aesthetic systems that determine how appealing an object is, be that a piece of cake or a piece of music.
We set out to understand which parts of the brain are involved in aesthetic appraisal. We gathered 93 neuroimaging studies of vision, hearing, taste and smell, and used statistical analyses to determine which brain areas were most consistently activated across these 93 studies. We focused on studies of positive aesthetic responses, and left out the sense of touch, because there were not enough studies to arrive at reliable conclusions.
The results showed that the most important part of the brain for aesthetic appraisal was the anterior insula, a part of the brain that sits within one of the deep folds of the cerebral cortex. This was a surprise. The anterior insula is typically associated with emotions of negative quality, such as disgust and pain, making it an unusual candidate for being the brain’s “aesthetic center.” Why would a part of the brain known to be important for the processing of pain and disgust turn out to the most important area for the appreciation of art?
Our interpretation of the result comes from cognitive theories of emotion that argue that aesthetic processing is, at its core, the appraisal of the value of an object -- in other words, an assessment of whether an object is “good for me” or “bad for me.” The nature of this appraisal depends very strongly on what my current physiological state is. The sight of chocolate cake will lead to positive aesthetic emotions if I’m famished but to feelings of disgust if I’m sick to my stomach. Objects that satisfy current physiological needs will lead to positive aesthetic emotions (e.g., pleasure). Those that oppose these needs will lead to negative emotions (e.g., repulsion).
How does the anterior insula fit into this story? In thinking about the contrast between internal and external environments, the anterior insula seems to be much more associated with the former than the latter. It is part of the brain’s “interoceptive” system, evaluating the state of the organs of our body. Other parts of the brain, then, respond directly to objects in the external environment: the sensory pathways of the brain. (One part of the cortex that seems particularly important for processing information across many sensory modalities is the orbitofrontal cortex.)
Brain areas such as the anterior insula and orbitofrontal cortex that are activated by pleasant smells or tastes are also the parts of the brain that are active when we are awed by Renaissance paintings or Baroque concertos. There is virtually no evidence that artworks activate emotion areas distinct from those involved in appraising everyday objects important for survival. Hence, the most reasonable evolutionary hypothesis is that the aesthetic system of the brain evolved first for the appraisal of objects of biological importance, including food sources and suitable mates, and was later co-opted for artworks such as paintings and music. As much as philosophers like to believe that our brains contain a specialized system for the appreciation of artworks, research suggests that our brain’s responses to a piece of cake and a piece of music are in fact quite similar.
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