Language context modulates reading route: an electrical neuroimaging study

Abstract

Introduction: The orthographic depth hypothesis (Katz and Feldman, 1983) posits that different reading routes are engaged depending on the type of grapheme/phoneme correspondence of the language being read. Shallow orthographies with consistent grapheme/phoneme correspondences favor encoding via non-lexical pathways, where each grapheme is sequentially mapped to its corresponding phoneme. In contrast, deep orthographies with inconsistent grapheme/phoneme correspondences favor lexical pathways, where phonemes are retrieved from specialized memory structures. This hypothesis, however, lacks compelling empirical support. The aim of the present study was to investigate the impact of orthographic depth on reading route selection using a within-subject design.Method: We presented the same pseudowords (PWs) to highly proficient bilinguals and manipulated the orthographic depth of PW reading by embedding them among two separated German or French language contexts, implicating respectively, shallow or deep orthography. High density electroencephalography was recorded during the task.Results: The topography of the ERPs to identical PWs differed 300–360 ms post-stimulus onset when the PWs were read in different orthographic depth context, indicating distinct brain networks engaged in reading during this time window. The brain sources underlying these topographic effects were located within left inferior frontal (German > French), parietal (French > German) and cingular areas (German > French).Conclusion: Reading in a shallow context favors non-lexical pathways, reflected in a stronger engagement of frontal phonological areas in the shallow versus the deep orthographic context. In contrast, reading PW in a deep orthographic context recruits less routine non-lexical pathways, reflected in a stronger engagement of visuo-attentional parietal areas in the deep versus shallow orthographic context. These collective results support a modulation of reading route by orthographic depth.

Balanced bilinguals favor lexical processing in their opaque language and conversion system in their shallow language

“…In a recent study minimizing the confounds related to intersubject heterogeneity and differences in stimuli lists, we found a modulation of the routine phonological non-lexical pathways engaged in pseudoword reading depending on the orthographic depth of language context (Buetler et al, 2014). The exact same pseudowords were presented to highly equi-proficient FrenchGerman bilinguals and the orthographic depth of PW reading was manipulated by embedding them among either a set of French (deep orthography) or German (shallow orthography) words.…”

“…The present study is based on a new analysis of data obtained by Buetler et al (2014), in which the procedure and task are already detailed; we thus present only the main methodological parameters here. In contrast to Buetler et al (2014), where pseudowords were analyzed, the present study contrasts ''natural" French versus German word reading.…”

“…In contrast to Buetler et al (2014), where pseudowords were analyzed, the present study contrasts ''natural" French versus German word reading.…”

“…However, when correcting for multiple comparisons [Bonferroni (Dunn, 1961) or Holm-Bonferroni (Holm, 1979)] to counteract false positive findings (Miller, 1966), none of the variables tested reached significance level (for details, see Buetler et al, 2014).…”

“…For this purpose, we focused on the EEG responses to the word stimuli presented to reinforce the linguistic context in Buetler et al (2014), resulting in a French versus German word reading contrast. Investigating reading in highly equi-proficient (French-German) bilingual subjects allowed to minimize potential confounds arising from intersubject comparisons.…”