UCLA

Previous research shows that experience with co-varying cues is neither sufficient nor necessary for listeners to integrate them perceptually. Auditory Enhancement theorists explain this by positing that listeners integrate two cues more readily if the cues enhance each other's percept. To isolate the role of enhancement from that of experience, we forced English adult listeners to shift attention between two enhancing cues that they do not use phonemically, pitch and breathiness, by reversing the informativeness of the two cues in a cue weighting experiment. Listeners were able to shift attention from pitch to breathiness and vice versa if the two cues were in an enhancing relation. When this relationship was reversed, listeners could shift attention from pitch to breathiness but not in the opposite direction. Clearly, both the change in informativeness and the enhancing properties of the cues influenced the listeners’ re-weighting of these cues. However, the directional asymmetry was not predicted. Moreover, the same asymmetry was observed in two new groups of listeners who have native language experience with either pitch or breathiness. We discuss the consequences of such asymmetric enhancement effects, rising from either processing limitations or articulatory contingencies, for language change.