Language proficiency moderates morphological priming in children and adults

A number of studies have shown that skilled readers decompose morphologically complex words upon encountering them (for a review, see Rastle & Davis, 2008). It has been proposed that this segmentation process is early and automatic and is driven by orthographic form, while being blind to semantic content, thus also called morpho-orthographic (Rastle, Davis, & New, 2004; Taft, 2003). One key finding in favor of this proposition comes from masked morphological priming: the recognition of a target word is facilitated when it is preceded by a morphologically related word prime (teacher-TEACH). Facilitation has also been found in a number of languages for targets preceded by pseudocomplex word primes that is words that appear to have a morphologically complex structure, but are simplex words (corner-CORN). Moreover, facilitation has as well been observed from complex pseudoword primes, that is a non-existing combination of a stem and affix (flexify-FLEX). For non-morphological nonword primes, that is a non-existing combination of a word and a nonmorphemic ending (flexint-FLEX), mixed results have been obtained (Longtin & Meunier, 2005; Morris, Porter, Grainger & Holcomb, 2011). Recent evidence from French points to a moderating role of language proficiency: the magnitude to which morpho-orthographic information is used increases as a function of individual vocabulary and spelling skills in adults (Andrews & Lo, 2013; Beyersmann, Casalis, Ziegler & Grainger, 2014). Only few studies have been concerned with morphological decomposition in beginning readers. The few studies from English and French used complex word primes, pseudocomplex word primes and non-morphological word primes. Quémart, Casalis and Colé (2011) found priming in French grade 3, 5, and 7 children from complex as well as pseudocomplex words, thus suggesting that children already use adultlike decomposition processes. In contrast, Beyersmann, Castles and Coltheart (2012) only found priming from truly complex words in grade 3 and 5 English-speaking children, indicating that morpho-orthographic priming is not automatized yet and decomposition relies more on semantics in developing readers. However, no studies with children have used complex pseudoword primes so far, although they provide the possibility to utilize the paradigm in languages that do not naturally have pseudocomplex words, such as German. Morphological decomposition in German can be insightful to investigate, because of its language specific characteristics. German has a transparent orthography and is morphologically rich. As a consequence, morphological entities might present a very useful unit for effective word recognition, even for beginning readers. Nevertheless, for children being still in the process of reading acquisition and showing more variability in their lexical representations, language proficiency can be expected to play an even greater role than Beyersmann et al. (2014) found for adults. The aim of the present study was therefore to test whether the moderating effect of lan-