Dependence, independence, and emergence of word features.

The degree to which a letter is perceived to be an e rather than a c is a function of the central, horizontal bar, which can be made to be more or less present in any given stimulus. By this means, word-form stimuli were produced through the independent, continuous manipulation of e versus c and of r versus h in two word frames (wat-- and --ase) yielding stimuli that ranged between water and watch in the former instance and between erase and chase in the latter. The identification probabilities for these stimuli were well accounted for in each case by a version of a fuzzy propositional model that is based on the assumption of independent features, indicating that the manipulated features within each word frame were not perceptually interdependent. However, the probabilities differed systematically between the two stimulus matrices; this means that there must be some other kind of higher order effect involved in identification. The hypothesis that the interaction was due to an emergent word envelope feature was rejected on the basis of the model analysis.