![]() What if there is no up or down in a control system, just a network of influences connecting all the parts? That descries a type of structure called a heterarchy. The principle of top-down and bottom-up processing: Complex systems produce optimal outcomes through interaction of top-down and bottom-up processing. In general, a delicate interplay of bottom-up and top-down processing is required for reading, object recognition, problem solving, memory, and all other cognitive activities. This leads them to expect the letter A in between the C and the T in Selfridge's example. Most people have repeatedly encountered the word cat many times, so they have that schema in their heads. Schemas (aka schemata) influence the interpretation of incoming data. A schema is a piece of organized knowledge formed by repeated experiences. A synonym for top-down in cognitive science is schema-driven. In cognitive science, a synonym for bottom-up is data-driven. Knowledge of words ( the and cat) leads us to see the same component first as an h, then as an a. Top-down processing occurs when knowledge of words guides interpretation of individual letters. The data from smaller components (letters) guides perception of a larger whole (a word). Top-down or schema-driven processing leads us to interpret the same shape two different ways.īottom-up processing occurs as the reader combines letters into words. ![]() Reading, for example, involves a combination of influences from high-level concepts or pre-existing knowledge (top-down processing) with influences from individual letters and words (bottom-up processing).Ĭonsider the following example from Neisser (1967, adapted from Selfridge, 1955). In cognitive science, a mixture of top-down and bottom-up processing is necessary for cognitive productions. A skillful mix of top-down and bottom-up processing is most effective. When people have a sense of controlling their own destiny, they tend to be happier. When people feel forgotten, unserved, or abused by their government, the society may disintegrate. Joseph Tainter suggested in The Collapse of Complex Societies (1988) that civilizations fail when "the flow of information from the bottom to the top is.inaccurate and ineffective." Obviously this provides an advantage, as long as the information is screened for relevance and importance.Ī coordination of top-down and bottom-up processing is necessary for optimal outcomes in most systems. If that information alters the behavior of the general, then the upper level of the hierarchy has been influenced by a lower-level element. When lower levels influence higher levels, this is called bottom-up processing.įor example, in an army, a general might benefit from a valuable piece of information passed on by a low-level intelligence officer. When upper levels (or big parts) influence lower levels (or components) this is called top-down processing. Most complex systems with hierarchical structure require a coordination of information or energy flow up and down the structure.
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