BELIEVING IS SEEING

A work of popular science centers on the act of seeing objects and scenes.

According to Levine, the understanding of sight as a straightforwardly mimetic representation of the external world is scientifically naïve. In fact, people constantly receive a deluge of “noisy, incomplete stimuli” that demands sorting and interpretation of the kind that finally paints a coherent, intelligible picture. Focusing on the identification of discrete objects and complex scenes, the author furnishes a rigorously researched account in which human perceptions are “influenced by assumptions beyond what is in the images themselves,” including overall context, attention, and expectation as well as even mood. This process requires more than merely the retina—newly understood as an “outpost of the brain”—but also the whole brain working collaboratively, including its “higher cognitive parts.” Ultimately, humans are trained to see not “distal” stimuli—the stuff that’s really out there independent of perception—but “proximal” stimuli, the “actual physical pattern available to neural receptors.” And so what we actually experience is an “elaborate internal representation of the world around us.” He asserts: “It is the ‘best’ solution our neural networks have settled upon. It is mainly visual, because we humans are generally visual animals, but it often includes sounds, odors, and physical sensations. We build this internal model when we look around us—it is the actual perception of which we are aware.” In this engaging book, Levine displays a talent for making the technically forbidding accessible. He also provides helpful images, some of which he photographed. (Others came from Getty.) But he spends too much time dwelling on secondary literature for a work not intended to be a “technical monograph or textbook,” making it unclear for whom it is intended. Still, he’s admirably free of dogmatism, readily admits when he can’t discover a “satisfying answer,” and, since the science is fluid, is quick to “concede that I am not about to divulge the eternal answers to the mysteries of sight.”

A captivating read for nonexperts with a deep scientific curiosity.