An Interactive Activation Model of Context Effects in Letter Perception: Part I. An Account of Basic Findings

Abstract

A model of context effects in perception is applied to the perception of letters in various contexts. In the model, perception results from excitatory and inhibitory interactions of detectors for visual features, letters, and words. A visual input excites detectors for visual features in the display. These excite detectors for letters consistent with the active features. The letter detectors in turn excite detectors for consistent words. Active word detectors mutually inhibit each other and send feedback to the letter level, strengthening activation and hence perceptibility of their constituent letters. Computer simulation of the model exhibits the perceptual advantage for letters in words over unrelated contexts and is consistent with the basic facts about the word advantage. Most importantly, the model produces facilitation for letters in pronounceable pseudowords as well as words. Pseudowords activate detectors for words that are consistent with most of the active letters, and feedback from the activated words strengthens the activations of the letters in the pseudoword. The model thus accounts for apparently rule-governed performance without any actual rules.