Novel Insights into Statistical Learning

Novel Insights into Statistical Learning Ian Simpson (isim2083@usyd.edu.au) Faculty of Health Sciences, University of Sydney Australia Joanne Arciuli (jarciuli@usyd.edu.au) Faculty of Health Sciences, University of Sydney Australia Abstract foundational study of adults’ ability to learn temporal relationships amongst visually presented shapes indicated significant SL after only 6 minutes of exposure (Fiser & Aslin, 2002). Recently, it was shown that infants less that a year old possess the capacity for VSL (Kirkham et al., 2002). There has been demonstration of the learning of position-dependent and position-independent statistical regularities using visually presented shapes (e.g., Fiser & Aslin, 2001) and the learning of real world scenes (Brady & Oliva, 2008). The claim that SL plays a key role in the acquisition of language stands in contrast with the persuasive notion that language is too complex and the language learner’s environment too impoverished for language acquisition to be subserved by a general learning mechanism. These views, combined with an assumption that cognitive functions are organized in a modular way, has led to the suggestion that language acquisition might be subserved by an innate mechanism (preprogrammed with information about linguistic universals). Patterson and Plaut (2009) cited Chomsksy: “…we take for granted that the organism does not learn to grow arms or to reach puberty…. When we turn to the mind and its products, the situation is not qualitatively different from what we find in the case of the body” (Chomsky, 1980, p. 2). The role of endowment versus learning during language acquisition has led to high-level and often feisty debate. Little attention has been given to a third possibility that incorporates both viewpoints – described as a kind of “innately guided learning” (Gould & Marler, 1987, p. 62; Yang, 2004). A lack of empirical evidence is preventing further scientific advances in this area – “current conceptualizations of these problems are driven more by theory than by data. ” (Gomez & Gerken, 2000, p. 180) In fact, it is premature to claim that SL has a significant role to play in language acquisition. There has been very little investigation of a link between a capacity for SL and spoken language proficiency. In a retrospective study, Newman et al. (2006) found that speech segmentation ability in infants (often attributed to SL) was linked to later proficiency with natural language at age 2 and 4–6. To our knowledge, there has been no examination of whether the capacity for SL is associated with the acquisition of written language. This latter gap in the research is surprising given the fact that children must be guided into a prolonged (and often effortful) period of The brain has a powerful capacity for statistical learning–an ability to detect statistical regularities in the environment in order to make predictions and guide behaviour–often without conscious awareness. It has been claimed that statistical learning plays a key role in a range of everyday perceptual and cognitive processes including those associated with language. There is demonstration that both spoken and written forms of natural language contain a rich statistical structure and there is demonstration that artificial languages are easier to learn when they contain statistical regularities. And yet, to date, there is very little empirical data showing a direct link between a capacity for statistical learning and proficiency with natural language. Here we report on a study of visual statistical learning that provides two important insights in the quest for such empirical evidence: this capacity follows a developmental trajectory in typically developing children, and it is correlated with reading ability. Keywords: statistical learning; visual statistical learning; reading. Statistical Learning The capacity for statistical learning (SL) can be assessed in a number of ways, for example, by presenting a continuous stream of evenly paced, individually presented items (be they objects, shapes, scenes, syllables, tones – represented here by letters) that contains embedded triplets such as …J– K–L–D–E–F–J–K–L–A–S–C… After brief exposure, participants are surprised with a forced-choice familiarity task and are able to identify embedded triplets (such as JKL) more reliably than foil triplets. This effect occurs even though (1) all individual items have been presented an equal number of times (2) there was no advance warning that there would be embedded patterns in the stream and (3) there was an absence of any kind of reinforcement. Participants often do not have any conscious sense of familiarity even when they exhibit significant levels of SL. A seminal study demonstrated that 8-month-olds can detect statistical patterns embedded in pseudospeech after only 2 minutes of exposure (Saffran et al., 1996). There is suggestion that SL might begin in utero (e.g., DeCasper et al., 1994; DeCasper & Spence, 1986) and evidence that it can operate on non-linguistic stimuli such as musical tones (e.g., Creel et al., 2004). To date, the majority of investigations of SL have examined the processing of auditory stimuli (ASL) although the number of studies examining visual stimuli (VSL) is steadily growing. A