2018 Sat Session C 1445
Saturday, November 3, 2018 | Session C, Terrace Lounge | 2:45pm
The more the merrier? The impact of talker variability on artificial grammar learning in preschoolers and adults
F. Bulgarelli, D. Weiss
A well-known challenge for language learners is that the input is typically produced by a variety of speakers, each with distinct vocal characteristics1. Accordingly, many studies have indicated that talker variability leads to processing costs for learners across the lifespan2,3,4.
However, increased talker variability can also be helpful for language learning5 by focusing learners on invariant properties of the signal. These discrepant findings may indicate that talker variability is akin to a desirable difficulty6 in learning. That is, initial costs in processing lead to long term benefits for retention and generalization. We investigated this hypothesis using an artificial grammar task modeled on dependencies found in languages with grammatical gender, which is acquired by 3yos in their native language7, but is notoriously difficult to acquire for adults8. Critically, this task afforded learning of novel object labels as well as grammatical dependencies, allowing testing of both retention and generalization.
We tested two groups of participants, 145 monolingual English speaking adults (=18.9y) and 69 preschoolers (=43.4m) at three separate time points: immediately after familiarization, after short delay (10-15m), and long delay (1 week). Within each group, participants were assigned to a condition with 1-, 2-, or 8-speakers. Learners were exposed to sentences describing novel objects. The object names were divided into two categories that were defined by word-final vowels which differed across categories, and preceded by a category- specific article (Figure 1). If talker variability acts as a desirable difficulty, we predicted that increased talker variability might lead to initially poorer performance but better long term outcomes, particularly for generalization.
Mixed-effects models were conducted for each test type (noun, article, generalization) across the three time points for each group. Across both groups, high talker variability did not lead to a processing cost for learning nouns at the immediate test (adults: t(94.2) = .92, p=.36; preschoolers: t(36.96) = .17, p=.86). However, low talker variability (2 speakers) impaired learning of the article-noun pairings for adults at all time points (performance not significantly above chance, all ps > .05), but led to above-chance performance for preschoolers immediately (t(17) = 2.38, p=.029) and after the short delay (t(17) = 2.41, p=.028, Figure 2). Only adults in the 8-speaker condition exhibited marginally-significant generalization after a short delay, t(48)= 2.0, p=.051. Adult participants exhibited retention of object labels and article-noun pairings, even after a week-long delay, independent of familiarization condition.
While we did not find processing costs associated with high talker variability, increased talker variability proved beneficial for learning the grammatical dependencies in adults. Further, the robust retention exhibited by adults provides insights regarding the durability of learning in artificial language paradigms. Interestingly, children and adults were differentially impacted by low talker variability, as it facilitated learning for preschoolers, while impeded learning for adults. These findings lend support to perceptual theories of talker-related learning that posit a protracted period of development4,9. In sum, our results provide evidence that optimal talker variability may vary by age, an insight that could bear implications for instructional settings.
References
1Liberman, A. M., Cooper, F. S., Shankweiler, D. P., & Studdert-Kennedy, M. (1967). Perception of the speech code. Psychological review, 74(6), 431.
2Jusczyl, P. W., Pisoni, D. B., & Mullennix, J. (1992). Some consequences of stimulus variability on speech processing by 2-month-old infants. Cognition, 43(3), 253-291.
3Mullennix, J. W., Pisoni, D. B., & Martin, C. S. (1989). Some effects of talker variability on spoken word recognition. The Journal of the Acoustical Society of America, 85(1), 365-378.
4Ryalls, B. O., & Pisoni, D. B. (1997). The effect of talker variability on word recognition in preschool children. Developmental Psychology, 33(3), 441.
5Rost, G. C., & McMurray, B. (2009). Speaker variability augments phonological processing in early word learning. Developmental science, 12(2), 339-349.
6Bjork, R. A. (1994). Memory and metamemory considerations in the. Metacognition: Knowing about knowing, 185.
7Mariscal, S. (2009). Early acquisition of gender agreement in the Spanish noun phrase: starting small. Journal of Child Language, 36(1), 143-171.
8Dewaele, J. M., & Véronique, D. (2001). Gender assignment and gender agreement in advanced French interlanguage: A cross-sectional study. Bilingualism: Language and Cognition, 4(3), 275-297.
9Creel, S. C., & Jimenez, S. R. (2012). Differences in talker recognition by preschoolers and adults. Journal of Experimental Child Psychology, 113(4), 487-509.