What are the functional orthographic units in Chinese word recognition: The stroke or the stroke pattern?

We present evidence that the visual analysis of Chinese characters by skilled readers is based upon well-defined orthographic constituents. These functional units are the recurrent, integral stroke-patterns, not the individual strokes as previously thought. The speed of simultaneous ''same-different'' comparisons of Chinese characters is affected by the number of these orthographic units and, for ''different'' judgements, by the proportion of mismatching units, but not by the number of individual strokes. We further define a category of orthographic unit, referred iu here as the ''lexical radical'', which requires strict positional regularity within each composite character. Violation of positional regularity results in illegal non-characters. In contrast, recombination of orthographic units (stroke patterns) with the lexical radical in its regular position forms a regular pseudocharacter. We show that real characters are matched faster than pseudocharacters and non-characters-a word superiority effect in Chinese. Pseudocharacters are matched faster than non-characters, a pseudoword advantage in Chinese. We also present evidence suggesting that individual stroke patterns may bf better recognized in real characters than in pseudocharacters and non-characters-a word superiority effect in terms of unit recognition. These results support the hypothesis that the functional orthographic unit in the recognition of Chinese characters, comparable to the letter in alphabetic word recognition, is the recurring integral stroke pattern.