Lexical Bias Effects do not Influence Responses to Real-Time Temporal Auditory Feedback Perturbation

In speech perception, listeners tend to hear real words rather than non-words on a physically balanced real word-non-word continuum (lexical bias effect). Bourguignon et al. found a similar effect in speech production: With spectral auditory feedback perturbations, they altered vowels toward other vowels thereby causing a shift in lexical status (from word to non-word or vice versa) or not. This study tests whether the lexical bias effect can be extended to the temporal domain in speech production. We perturbed the German vowels /a/ and /a:/ in real words toward the respective other phoneme using a real-time temporal auditory feedback adaptation paradigm. This manipulation pushed the percepts either toward another real word (lexical condition) or not (non-lexical condition). In both perturbation setups (stretching short /a/, or compressing long /a:/), speakers counteracted the perturbation with productions opposing the direction of perturbation. However, response magnitude was similar across conditions, that is, independent of a shift in lexical status. The results indicate that, in the temporal domain, speakers do not heavily rely on higher-level linguistic information, but rather are principally oriented toward maintaining phonemic identification. These findings further imply that temporal and spectral parameters in speech production and perception are governed by different processing strategies.