Schematic Structure, Hebbian Learning, and Semantic Change

Abstract

This chapter aims to explain some trends in semantic change with Hebbian learning. Semantic broadening observed in grammaticalization is argued to be seeded by speakers when they select frequent forms for production over less accessible competitors, even though the meaning they are trying to express is merely similar to the meanings the frequent form was experienced in. Extension of frequent forms in production co-exists with entrenchment (the suspicious coincidence effect) in comprehension. The entrenchment effect in comprehension rules out a habituation account of the semantic change. The form a speaker is most likely to extend to a new meaning in production is often the form they are least likely to map onto that meaning in comprehension. A range of Hebbian models of these processes is developed. All such models are shown to predict the comprehension-production dissociation under default assumptions regarding salience differences between absent and present cues. Certain aspects of the results are shown to be problematic for error-driven models (Rescorla-Wagner), at least if learning rate is fast enough to give rise to their signature blocking effect. Finally, an account of accessibility in an associative framework is developed.