The Neccessity of Selective Attention

Three decades ago, cognitive scientist Colin Martindale advanced the idea that each of us has several subselves, and he connected his idea to emerging ideas in cognitive science. Central to Martindale’s thesis were a few fairly simple ideas, such as selective attention, lateral inhibition, state-dependent memory, and cognitive dissociation. Although there are billions of neurons in our brains firing all the time, we’d never be able to put one foot in front of the other if we were unable to ignore almost all of that hyperabundant parallel processing going on in the background. When you walk down the street, there are thousands of stimuli to stimulate your already overtaxed brain—hundreds of different people of different ages with different accents, different hair colors, different clothes, different ways of walking and gesturing, not to mention all the flashing advertisements, curbs to avoid tripping over, and automobiles running yellow lights as you try to cross at the intersection. Hence, attention is highly selective. The nervous system accomplishes some of that selectiveness by relying on the powerful principle of lateral inhibition—in which one group of neurons suppresses the activity of other neurons that might interfere with an important message getting up to the next level of processing. In the eye, lateral inhibition helps us notice potentially dangerous holes in the ground, as the retinal cells stimulated by light areas send messages suppressing the activity of neighboring neurons, producing a perceived bump in brightness and valley of darkness near any edge. Several of these local “edge detector”–style mechanisms combine at a higher level to produce “shape detectors,” allowing us to discriminate a “b” from a “d” and a “p.” Higher up in the nervous system, several shape detectors combine to allow us to discriminate words, and at a higher level to discriminate sentences, and at a still higher level to place those sentences in context (thereby determining whether the statement “Hi, how are you today?” is a romantic pass or a prelude to a sales pitch).

Douglas T. Kenrick explains how our senses are bombarded, so we filter. If we could not filter, we would become incapacitated.