Humans may find images that take less energy to process aesthetically pleasing, suggesting that our attraction to beauty is at least partially an energy conservation strategy.
Looking at something can feel effortless, but in energetic terms, it isn't cheap. The brain uses 20% of the body's energy, and the visual system accounts for about 44% of that expenditure. Looking at very simple stimuli, like a blank white room, is energy-efficient but boring. Looking at very busy or unusual image can feel tiring and unpleasant. Yikai Tang and colleagues presented 4,914 images of objects and scenes to an in-silico model of the visual system to estimate the number of neurons needed to look at them. The authors compared these estimates to enjoyment ratings from 1,118 participants recruited using Amazon Mechanical Turk. Next, the authors used blood oxygen level-dependent signal brain imaging to measure the energy costs of looking at images for 4 participants. In both experiments, study participants found images that took less energy to process more attractive. The authors asked for a quick response, meant to capture initial impressions, not the more complex pleasures that may arise from contemplating an image in a broader context by engaging with its meaning. According to the authors, visual aesthetic appreciation may be a manifestation of an energy-conserving heuristic that creates a sweet spot between sufficient stimulation of the visual system and excessive metabolic cost—a finding giving new meaning to the idiom, "easy on the eyes."
