the task (i.e., that there should only be one letter in one place at one time), to
produce perceptual completion in a simple and direct way.
Completion of Novel Patterns However, the perceptual intelligence of human
perceivers far exceeds the ability to recognize familiar patterns and fill in miss-
ing portions .We also show facilitation in the perception of letters in unfamiliar
letter strings which are word-like but not themselves actually familiar.
One way of accounting for such performances is to imagine that the perceiver
possesses, in addition to detectors for familiar words, sets of detectors for reg-
ular subword units such as familiar letter clusters, or that they use abstract
rules, specifying which classes of letters can go with which others in different
contexts .It turns out, however, that the model we have already described
needs no such additional structure to produce perceptual facilitation for word-
like letter strings; to this extent it acts as if it ‘‘knows’’ the orthographic
Figure 4.8
A possible display which might be presented to the interactive activation model of word recogni-
tion, and the resulting activations of selected letter and word units .The letter units are for the
letters indicated in the fourth position of a four-letter display.
The Appeal of Parallel Distributed Processing 73