No abstract

The functional sensorimotor nature of speech production has been demonstrated in studies examining speech adaptation to auditory and/or somatosensory feedback manipulations. These studies have focused primarily on flexible motor processes to explain their findings, without considering modifications to sensory representations resulting from the adaptation process. The present study explores whether the perceptual representation of the /s-b/ contrast may be adjusted following the alteration of auditory feedback during the production of /s/-initial words. Consistent with prior studies of speech adaptation, talkers exposed to the feedback manipulation were found to adapt their motor plans for /s/-production in order to compensate for the effects of the sensory perturbation. In addition, a shift in the /s-b/ category boundary was observed that reduced the functional impact of the auditory feedback manipulation by increasing the perceptual "distance" between the category boundary and subjects' altered /s/-stimuli-a pattern of perceptual adaptation that was not observed in two separate control groups. These results suggest that speech adaptation to altered auditory feedback is not limited to the motor domain, but rather involves changes in both motor output and auditory representations of speech sounds that together act to reduce the impact of the perturbation.

Normal aging is an inevitable race between increasing knowledge and decreasing cognitive capacity. Crucial to understanding and promoting successful aging is determining which of these factors dominates for particular neurocognitive functions. Here, we focus on the human capacity for language, for which healthy older adults are simultaneously advantaged and disadvantaged. In recent years, a more hopeful view of cognitive aging has emerged from work suggesting that age-related declines in executive control functions are buffered by life-long bilingualism. In this paper, we selectively review what is currently known and unknown with respect to bilingualism, executive control and aging. Our ultimate goal is to advance the view that these issues should be reframed as a specific instance of neuroplasticity more generally and, in particular, that researchers should embrace the individual variability among bilinguals by adopting experimental and statistical approaches that respect the complexity of the questions addressed. In what follows, we set out the theoretical assumptions and empirical support of the bilingual advantages perspective, review what we know about language, cognitive control and aging generally, and then highlight several of the relatively few studies that have investigated bilingual language processing in older adults, either on their own or in comparison with monolingual older adults. We conclude with several recommendations for how the field ought to proceed to achieve a more multifactorial view of bilingualism that emphasizes the notion of neuroplasticity over that of simple bilingual vs monolingual group comparisons. 3Moving Toward a Neuroplasticity View of Bilingualism, Executive Control and Aging Normal aging is an inevitable race between increasing knowledge and decreasing cognitive capacity. Crucial to understanding and promoting successful aging is determining which of these factors dominates for particular neurocognitive functions. Here, we focus on the human capacity for language, for which healthy older adults are simultaneously advantaged and disadvantaged.Older adults have greater word knowledge than younger adults, and make greater use of context when using language than younger adults (Wingfield & Tun, 2007). However, age-related deficits in perceptual acuity (Murphy, Daneman, & Schneider, 2006;Schneider, Daneman, & Pichora-Fuller, 2002;Schneider, Li, & Daneman, 2007;Stewart & Wingfield, 2009;Tun, McCoy, & Wingfield, 2009;Wingfield, McCoy, Peelle, Tun, & Cox, 2006) and executive control functions such as working memory and inhibitory capacity, counter these advantages (Burke, 1997;Burke & Shafto, 2004;Darowski, Helder, Zacks, Hasher, & Hambrick, 2008;Hasher, Lustig, & Zacks, 2007;Martin, Brouillet, Guerdoux, & Tarrago, 2006;Salthouse & Meinz, 1995). Thus, language processes that rely on executive control, such as the resolution of linguistic competition during spoken and written comprehension, and production, are especially vulnerable for older adults (Abada, Baum, & Titone, 2...