Can Chunk Size Differences Explain Developmental Changes in Lexical Learning?

Abstract

In three experiments, we investigated Hebb repetition learning (HRL) differences between children and adults, as a function of the type of item (lexical vs. sub-lexical) and the level of item-overlap between sequences. In a first experiment, it was shown that when non-repeating and repeating (Hebb) sequences of words were all permutations of the same words, HRL was slower than when the sequences shared no words. This item-overlap effect was observed in both children and adults. In a second experiment, we used syllable sequences and we observed reduced HRL due to item-overlap only in children. The findings are explained within a chunking account of the HRL effect on the basis of which we hypothesize that children, compared with adults, chunk syllable sequences in smaller units. By hypothesis, small chunks are more prone to interference from anagram representations included in the filler sequences, potentially explaining the item-overlap effect in children. This hypothesis was tested in a third experiment with adults where we experimentally manipulated the chunk size by embedding pauses in the syllable sequences. Interestingly, we showed that imposing a small chunk size caused adults to show the same behavioral effects as those observed in children. Departing from the analogy between verbal HRL and lexical development, the results are discussed in light of the less-is-more hypothesis of age-related differences in language acquisition.

The role of overt language production in the Hebb repetition effect

“…This is consistent with other studies suggesting that perceptual processes might play a more important role than production processes during longterm learning (Bower & Winzenz, 1969;Burgess & Hitch, 2006;Hitch et al, 2009;O'Shea & Clegg, 2006;Page & Norris, 2009;Schwartz & Bryden, 1971). Finally, our results further strengthen the view that Hebbian learning mimics natural word-form learning (Page & Norris, 2009;Smalle et al, 2016;Szmalec et al, 2009;Szmalec et al, 2012).…”

“…In effect, it has been assumed that backward recall is an executive demanding operation (Szmalec & Vandierendonck, 2007;Szmalec, Vandierendonck, & Kemps, 2005). Under this view, the similar learning rate in both recall direction parallel results found with word-form learning showing that it is independent of executive control (Smalle et al, 2016;Szmalec, Page, & Duyck, 2012).…”

Children retain implicitly learned phonological sequences better than adults: a longitudinal study

“…While a main effect of Sequence type in favor of the Hebb sequence might provide some evidence of learning that sequence, only the demonstration of improvements in performance for repeated Hebb sequences relative to improvements in the baseline filler sequences may be considered a pure indication of learning. Thus, an interaction between Sequence type and Time point, due to higher scores on the Hebb sequences for the final time point, would provide evidence for Hebb learning (Smalle et al., ). Overall, adults showed higher recall scores than children (main effect of Age group, F (1, 53) = 32.1, p < .001, ɳ 2 p = .38).…”

“…It shows that children compensate for lower memory storage capacity by other, probably more implicit, mechanisms which become evident in the Hebb learning task. In an earlier Hebb learning study, where the length of the Hebb sequences was adjusted to the working memory span of children and adult groups, therefore making the age groups comparable on initial level of performance, children even outperformed adults on Hebb‐repetition learning (Smalle et al., ). This earlier finding and the present work together strengthen the hypothesis that children outperform adults in their use of implicit sequence‐learning mechanisms that are related to language (see also, for instance, Smalle, Muylle, Szmalec & Ducyk, ).…”

“…Experimental work has supported this idea by showing that sub‐sequences acquired through HRL are represented in the mental lexicon just like novel words, exhibiting competition effects with existing words (which is an important indication of lexicalization; see Leach & Samuel, ; Szmalec et al., ; Szmalec et al., ). HRL is also fast and long‐lasting (Page, Cumming, Norris, McNeil, & Hitch, ), and correlated with measures of word‐learning and vocabulary knowledge (Majerus & Boukebza, ; Majerus, Poncelet, Elsen, & Van der Linden, ); it is observed in children (Mosse & Jarrold, ; Smalle et al., ); and it has been shown to be impaired in people with certain language disorders (Archibald & Joanisse, ; Bogaerts, Szmalec, De Maeyer, Page, & Duyck, ; Bogaerts, Szmalec, Hachmann, Page, & Duyck, ; Hsu & Bishop, ; Szmalec, Loncke, Page, & Duyck, ).…”