Phonetic training makes word learning easier

Phonetic training makes word learning easier Amy Perfors (amy.perfors@adelaide.edu.au) Department of Psychology, University of Adelaide David Dunbar (david.dunbar@student.adelaide.edu.au) Department of Psychology, University of Adelaide Abstract Motivated by the idea that differences between adult and child language learners may stem in part from initially minor differ- ences (such as in phonetic perception) that cascade throughout other aspects of language learning, we explored to what extent training adults on a novel phonetic contrast results in improved learning of words that incorporate that contrast. Results indi- cate that distributional training on a novel phonetic contrast improves word learning as well as the ability to discriminate a related contrast. We discuss implications for how adults’ phonological abilities in affect other aspects of language learn- ing, and also for understanding the effectiveness of different phonetic training regimes. Keywords: language acquisition; phonetic learning; second language learning Introduction Children and adults differ both qualitatively and quantita- tively in their ability to acquire a new language. Adults have difficulty with many aspects of language acquisition, from phonetic perception (Werker & Tees, 1984; Werker & Lalonde, 1988; Kuhl, 2004) to language processing (Clahsen & Felser, 2006) to certain aspects of syntax (e.g., Johnson & Newport, 1989; Birdsong, 2006). Scientists have proposed many theories to account for the difference between children and adults; these theories differ in both the degree and type of contribution made by pre-existing language-specific biases. Although nearly everyone agrees that (due to the inherent log- ical problem of induction posed by language learning) some bias must be necessary to explain successful language acqui- sition, explanations about the nature of the bias – and the dif- ference between children and adults – vary considerably. Some argue that there is a fundamental difference between first and second language acquisition: that acquisition in chil- dren is guided by an innate Universal Grammar and language- specific acquisition procedures, but that adult acquisition is directed by more domain-general learning mechanisms (e.g., Bley-Vroman, 1990). There are many other possibilities, however, since children and adults differ profoundly in their cognitive capabilities and typical linguistic input. Children have significantly poorer cognitive skills, including memory and processing speed; perhaps these differences aid children to learn language by enabling them to isolate and analyze components of a linguistic stimulus (Newport, 1988) or to over-regularize inconsistent input (Hudson Kam & Newport, 2005; Singleton & Newport, 2004). Another possibility is that learning a second language is made more difficult due to interference from the first language; indeed, the evidence that experience with a first language influences acquisition of a second is extensive (e.g., Mayberry, 1993; Iverson et al., 2003; Tan, 2003; Weber & Cutler, 2003; Hernandez, Li, & MacWhinney, 2005). This explanation overlaps considerably with the related point that adult brains are in many ways less plastic, and therefore less malleable in response to novel input (Elman et al., 1996; MacWhinney, 2005). Other explanations suggest that adults and children differ in their style of learn- ing (Ullman, 2004) as well as the nature of the social support (Snow, 1999) and linguistic input (Fernald & Simon, 1984) they receive. Of course, many of these possibilities may be true simultaneously. This work investigates yet another possibility – that small differences in children’s abilities along one dimension or as- pect of language can have cascading effects, resulting in larger differences in other aspects of language. These ini- tial minor differences might be due to language-specific skills that naturally decay over time, or could be due to domain- general changes in the underlying cognitive abilities that sub- serve them. Key to this idea is the notion that, because lan- guage is such an intertwined, multi-dependent system, small differences in one aspect of language can be steadily ampli- fied when it comes to the acquisition of other aspects. This idea is similar to the neo-constructivist view of Karmiloff- Smith (1998): both suggest that differences in eventual lin- guistic performance may derive from cascading effects that result from variation in more basic skills. That view focuses on abnormal development in children, however. Our work is motivated by an extension of this viewpoint: the notion that some of the well-attested differences between child and adult learners may result from the more minor, lower-level differ- ences between adults and children. To investigate this, we be- gin by identifying aspects of language acquisition where one might expect to see cascading effects, and investigate whether performance in one improves performance in the other. What minor difference between adults and children might have significant cascading effects onto other aspects of lan- guage? One possibility derives from children’s well-attested superior phonological processing and perception abilities. Young infants can distinguish between phonemes in all natu- ral languages, but lose that ability by the age of 10-12 months if they have not received sufficient linguistic input for a lan- guage containing that phoneme (Eimas, Siqueland, Jusczyk, & Vigorito, 1971; Werker & Tees, 1984; Kuhl, 2004). Adults who begin acquisition of a language later in life, even after decades of experience using the language, show phonolog- ical deficits in perception, production, and processing (e.g., Flege, 1995; Pallier, Colom´e, & Sebasti´an-Gall´es, 2001; Se- basti´an-Gall´es & Soto-Faraco, 1999).