A more illuminating perspective on both perception and memory is the concept of schemata, the meaningful elements of our visual environment. You or I can identify a friend’s face in a group photo in seconds or less. In contrast, if you had to help someone else find your friend by describing the friend’s characteristics, identification would be dilatory and uncertain. Evolutionary pressure favors fast identification: survival may depend on rapid recognition of predators. Obviously our pattern recognition techniques, whether of predators or friends, are extremely efficient and unconscious. Schemata achieve that needed speed.
Schemata are the building blocks of memories and of pattern recognition. An individual schema is somewhat like one of Plato’s forms: an idealized representation of an object’s essence. It may not match any specific object that we have seen. Instead, it is a composite constructed from our history of observing and recognizing examples of the object. A group of neural pathways fires during our first exposure to the object, thereby becoming associated with the object. Later recognition of the object triggers re-firing along these paths.
Schemata are somewhat like the old rhyme,
“Big fleas have little fleas On their backs to bite 'em, And little fleas have smaller fleas And so ad infinitum.”
Even a schema as ‘simple’ as pencil is made up of many other schemata: textural (e.g., hard), morphological (e.g., elongated, cylindrical, conical-ended), and especially functional. And an individual schema such as cylindrical is composed of lower-level schemata. Another example of a schema is a musical composition, composed of lower-level patterns of a few bars each, and -- at the lowest level -- notes.
It all sounds hopelessly cumbersome, but the process is an elegantly efficient flow of electrical currents in parallel. Identification of a pattern does not require identification of all its elements, and identification of a higher-level schema such as pencil does not await identification of all the lowerlevel schemata components. If I see a snake, then I do not have the luxury of a casual and completely reliable identification: the schemata sinuous, cylindrical, 6" to 6' (however that information is stored as schema), and moving may trigger a jump response before I realize why I am jumping. I’ve seen a cat jump straight up into the air on encountering a sinuous stick.
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We filter out all but the tiniest fraction of our sensory inputs; otherwise we would go mad. One by one, we label and dismiss these signals, unconsciously telling them, “You’re not important; don’t bother me.”
“Novelty itself will always rivet one’s attention. There is that unique moment when one confronts something new and astonishment begins. Whatever it is, it looms brightly, its edges sharp, its details ravishing, in a hard clear light; just beholding it is a form of revelation, a new sensory litany. But the second time one sees it, the mind says, Oh, that again, another wing walker, another moon landing. And soon, when it’s become commonplace, the brain begins slurring the details, recognizing it too quickly, by just a few of its features.” [Ackerman, 1990]
Schema modification begins immediately after first exposure, with a memory replay of the incident and the attempt to name it and associate it with other incidents. Schema development may be immediate or gradual, and this rate is affected by many factors, particularly emotion and pain. Consider the following three experiments:
