Top-Down and Bottom-Up Processing

When an interpretation emerges from the data, this is called data-driven or bottom-up processing. Perception must be largely data-driven because it must accurately reflect events in the outside world. You want the interpretation of a scene to be determined mostly by information from the senses, not by your expectations.

What is data-driven or bottom-up processing? What is schema-driven or top-down processing?

In many situations, however, your knowledge or expectations will influence perception. This is called schema-driven or top-down processing. A schema is a pattern formed earlier in your experience.

Larger scale or more abstract concepts are referred to as higher level, while concrete details (such as the input from the senses) are referred to as lower level. Top-down processing occurs any time a higher-level concept influences your interpretation of lower level sensory data.

What is set or expectancy?

Top-down processing is shown by the phenomena of set or expectancy. A classic example is the Rat Man of Bugelski and Alampay (1961).


The "Rat-Man" picture

Subjects saw this picture after viewing earlier slides that showed line drawings of (1) animals, or (2) faces. Depending on whether they saw animals or faces in previous slides, subjects reported seeing either (1) a rat or (2) a man wearing glasses. They had been "set" for one or the other interpretation by the preceding slides. This is a form of top-down processing, in which a schema influences interpretation of the data.

In what respect do cartoons rely upon top-down processing?

Comics and cartoons provide many examples of top-down processing. Simple cues are used to suggest complex feelings and emotions. Cartoonists have a set of conventions for conveying information about mental and physical states. Tiny popping bubbles, for example, show drunkenness. Movement is shown by lines and little puffs of dust trailing after shoes. Spoken language is shown inside a bubble made out of a continuous line. A silent thought is shown inside a broken line. A sudden idea may be shown as a lightbulb lighting up over a character's head. Beads of sweat flying off a character show anxiety or physical exertion. After one gains some experience reading comics, these cues are processed automatically; one is hardly aware of them.

In what sense do we go "beyond the information given"?

In general, top-down processing—information processing based on previous knowledge or schemata—allows us to make inferences: to "perceive" or "know" more than is contained in the data. Little cartoon droplets do not contain the information that a character is working hard. We add that information based upon our previous experience and knowledge of the conventions of cartooning.

Jerome Bruner titled a book about cognitive development Beyond the Information Given (1972) He was acknowledging the pivotal role of inference in cognition. We go "beyond the information given" constantly in our mental processes. We learn to add assumptions and supplemental information derived from past experience to the evidence of our senses, and that is how we make sense of our world.


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Copyright © 2007 Russ Dewey