Complexity in Output Systems: Evidence from Behavioral Hybrids

Abstract

The speech errors known as synonymic intrusions (e.g., 'sotally,' an inadvertent combination of initial word 'solely' and sequel word 'totally' in 'He was sotally responsible for that') suggest that two or more words can be simultaneously activated, competing for the same position in a sentence. Statistical analysis of 257 such intrusions showed that the intruding word (or phrase) was simpler than the initial one at the segment, syllabic, lexical, and at two syntactic levels. A hierarchic model for the serial production of speech, and more generally, for the study of other motor systems, is proposed. Speech errors place strong constraints on theories of speech production, since an adequate model of normal speech must also allow for those errors, as does the actual speech-production system. Conversely, an adequate explanation of speech errors must incorporate the general principles of normal speech production, in the sense that an explanation of the backfiring of an automobile engine must incorporate the general principles of internal combustion. The present study explores some of the implications of this metatheory for theories of speech production as well as other motor systems. Our more specific goal was to infer the nature of the speech-production system that generates the speech errors known as synonymic intrusions. Synonymic intrusions represent a class of behavioral hybrids that occur whenever a speaker begins with one expression (defined as the initial phrase or word) and inadvertently continues with another expression having roughly equivalent meaning. The intruding constituent is defined as the sequel phrase or word. Consider the synonymic intrusion 'I am together,' an inadvertent combination of 'I am with you' (initial phrase) and 'We are together' (sequel phrase). What must be explained in such combinations is why the initial phrase stops where it does. One might suggest that the speaker is switching his message or revising his meaning when he makes such errors. But the fact that the initial and sequel phrases are synonymic, or semantically