Inhibition and Facilitation in Auditory Comprehension Across the Lifespan - eScholarship

Inhibition and Facilitation in Auditory Comprehension Across the Lifespan Henrike K. Blumenfeld (hblumenf@mail.sdsu.edu) School of Speech, Language, and Hearing Sciences, 5500 Campanile Drive San Diego, CA 92182 USA Scott R. Schroeder (schroeder@u.northwestern.edu) Zahra R. Ali (zahraali2007@u.northwestern.edu) Viorica Marian (v-marian@northwestern.edu) Department of Communication Sciences and Disorders, 2240 Campus Drive Evanston, IL 60208 USA Abstract threshold becomes necessary for successful word selection. Therefore, we reasoned that the relationship between inhibition and activation during word recognition would dynamically change with age. In an auditory word identification task, participants identified the picture of a target word (cab) from among a picture of a similar- sounding competitor (cat) and pictures of two neutral filler words (bus, ant). Immediately following each picture identification trial, participants completed a priming trial, where residual target activation and competitor inhibition were probed. Younger adults were predicted to inhibit competitors and efficiently identify target words. In contrast, older adults were predicted to show greater target- competitor interference, less competitor inhibition, and increased target activation at the time of word selection. The relationship between activation and inhibition in word comprehension was examined in younger and older adults by using a novel Picture Identification / Negative Priming paradigm. Picture identification results showed increased interference from similar-sounding competitor words in older (compared to younger) adults. Subsequent priming probe results yielded reduced competitor inhibition with increased target word facilitation in older (compared to younger) adults. Findings suggest a link between activation and inhibition in younger adults and age-related changes in word selection mechanisms, with increased compensatory target facilitation accompanying decline in inhibitory control. Implications for models of word recognition are discussed. Keywords: Inhibition; facilitation; negative priming; auditory word recognition; cognitive aging. Methods Introduction A number of distributed and connectionist models formalize mechanisms of auditory word recognition (e.g., Marslen- Wilson, 1987; McClelland & Elman, 1986). These models posit that words are identified from the speech stream via parallel activation of multiple similar-sounding candidates, where target words are selected once sufficient acoustic information becomes available. In addition, some models, such as McClelland and Elman’s (1986) TRACE Model, posit that lexical-level lateral inhibition between competing word candidates contributes to target word selection. Indeed, inhibitory control has been experimentally shown to contribute to comprehension (Gernsbacher, 1990; Swinney, 1979). While it is intuitive that activation and inhibition mechanisms interact, few accounts specify the nature of this interaction. Since abilities of inhibitory control decline with age (Comalli, Wapner, & Werner, 1962; Hasher & Zacks, 1988), one way to examine the interaction between inhibition and activation is to study their magnitude during comprehension in younger vs. older adults. In older adults, decline in inhibitory control has been linked to decline in auditory comprehension abilities (e.g., Sommers & Danielson, 1999; Taylor et al., 2005). However, it is likely that, as inhibitory control abilities decline, older adults employ compensatory strategies to maintain performance. For example, it is possible that, as inhibitory control becomes less efficient, target activation to a higher Participants Thirty English-native younger monolingual adults (M age = 21.4, SD = 3.9; 4 males) and 28 English-native older monolingual adults (M age = 73.3, SD = 10.3) were recruited. Participants were administered the Language Experience and Proficiency Questionnaire (Marian, Blumenfeld, & Kaushanskaya, 2007) and a number of standardized linguistic and cognitive tasks (see Table 1). Younger and older adults were matched on the percentage of time they were currently exposed to their native English (as opposed to foreign languages), on expressive vocabulary knowledge (as measured by the standard score on the Peabody Picture Vocabulary Test-III), on nonverbal IQ (as measured by the Wechsler Abbreviated Scale of Intelligence), and on digit span performance (as measured by the Comprehensive Test of Phonological Processing), p > . 05. Task The paradigm included two types of trials, which were presented in alternating order (see Figure 1). Word Recognition / Picture Identification trials were presented first and indexed activation of target and competitor words, relative to control words, during word recognition. Priming Probe trials were presented next and indexed inhibition of preceding competitor words and facilitation of preceding