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Department of Cognitive Science

Seminar Abstract

Long-term adaptation to uncertainty in lexical processing by Cochlear Implant Users: Beyond perceptual retuning. (CLaS-CCD Research Colloquium Series)

Speaker : Professor Bob McMurray, Department of Psychological and Brain Sciences, University of Iowa, USA.
Date : 28th of April 2017, 11:00AM until 12:00PM
Location : Australian Hearing Hub, Level 3, 3.610, Macquarie University.

    The last decade has seen an explosion of work documenting the rapid and broad-based plasticity of speech perception (Bradlow & Bent, 2008; Davis, Johnsrude, Hervais-Adelman, Taylor, & McGettigan, 2005; Idemaru & Holt, 2011; Norris, McQueen, & Cutler, 2003). For the most part this suggests precise changes to the details of perception: cue weightings, boundaries and so forth. However, such mechanisms may be less effective when sensory limitations prevent a fine-grained analysis of the signal. This talk asks if there are additional ways to adapt the system. One group of listeners where this may be important is profoundly deaf listeners who use Cochlear Implants (CIs). CIs systematically distort the input– reducing sensitivity to frequency distinctions, eliminating periodicity, and attenuating access to low frequencies. However, most post-lingually deafened—and many pre-lingually deafened—CI users achieve impressive speech perception (Clark et al., 2012; Dunn et al., 2014; Svirsky, Robbins, Kirk, Pisoni, & Miyamoto, 2000). These gains typically require months or years of experience to achieve (Hamzavi, Baumgartner, Pok, Franz, & Gstoettner, 2003; Oh et al., 2003), suggesting some form of adaptation, but it is not clear what precisely is adapting (c.f., Moberly et al., 2014). This talk presents a series of studies of both post-lingually and pre-lingually deafened CI users, as well as normal hearing individuals confronted with CI simulated (vocoded) speech that examine how listeners adapt to this form of degradation. Together, this work suggests lexical competition is not just an automatic consequence of the temporarily unfolding input; rather the strength by which candidates compete is a way of managing ambiguity. These changes raise the possibility that CI users may manage their uncertainty by tuning these lexical dynamics to the kinds of input they receive.

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