The Programmable Blackboard Model of Reading

In 1975 , Rumelhart outlined a model of reading called the interactive mode/. That model , inspired by the HEARSAY model of speech understanding (Reddy, Erman , Fennell , & Neely, 1973), supposed that reading involved simultaneous processing at a large number of levels including visual feature, letter , word; syntactic , and semantic levels. Hypotheses at each level were activated when active hypotheses on adjacent levels suggested them and competed with alternative hypotheses at the same level. This model , of course , was a precursor of the interactive activation model of word recognition and of the approach that underlies this whole book. In the interactive model of reading, the activation of hypotheses was guided by a set of structures called" knowledge sources " each of which had expertise with respect to a particular aspect of reading. For example , a lexical knowledge source that contained knowledge of the letter sequences that made up each word was proposed , along with a syntactic knowledge source , a semantic knowledge source, and an orthographic knowledge source containing knowledge of the appearance of the letters.