Word Recognition, Visual

The Architecture of the Visual Word Recognition System

Though the earliest theories of visual word recognition claimed that words are recognized as wholes on the basis of their shapes, modern theories suggest that words are recognized in a hierarchical manner on the basis of their components. Information from the printed stimulus maps onto stored knowledge about the visual features that make up letters (e.g., horizontal bar, left-opening curve), and information from this level then proceeds onto a system of stored abstract letter representations that code letter identity as well as letter position (so that anagrams like top, pot, and opt can be distinguished). These letter representations are abstract in the sense that they can be activated irrespective of surface characteristics such as case, size, font, and retinal location. Information at the letter level of representation then proceeds onto an orthographic lexicon (a body of stored knowledge about the written forms of whole words). Units in the orthographic lexicon can then activate information about the meanings and/or sounds of words. Visual word recognition is thought to be achieved when a unit in the orthographic lexicon reaches some critical threshold of activation.

There is widespread agreement that each unit in the orthographic lexicon is coded in terms of an individual's experience with that word. Precisely how lexical experience is best conceptualized is a matter of some debate, however. Until recently, most theories argued that orthographic units are coded in terms of the frequency with which a word occurs in the language, and indeed, word frequency is known to be the most powerful determinant of the time taken to recognize a word (i.e., its latency). However, recent research has suggested that the age at which words are acquired, or perhaps the cumulative frequency with which an individual encounters words over his or her lifetime, may provide a better means of conceptualizing lexical experience. Both age of acquisition and cumulative frequency have also been shown to influence word recognition latencies, though because age of acquisition, cumulative frequency, and word frequency are naturally correlated, it is not yet known which variable provides the optimal index.

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