Early print-tuned ERP response with minimal involvement of linguistic processing in Japanese Hiragana strings

Abstract

The act of reading leads to the development of specific neural responses for print, the most frequently reported of which is the left occipitotemporal N170 component of event-related potentials. However, it remains unclear whether this electrophysiological response solely involves print-tuned neural activities. The present study examined an early print-tuned event-related potential response with minimal involvement of linguistic processing in a nonalphabetic language. Japanese Hiragana words, nonwords, and alphanumeric symbol strings were presented rapidly and the task was to detect the change in color of a fixation cross to restrict linguistic processing. As a result, Hiragana words and nonwords elicited a larger posterior N1 than alphanumeric symbol strings bilaterally, irrespective of intercharacter spacing. The fact that this N1 was enhanced specifically for rapidly presented Hiragana strings suggests the existence of print-tuned neural processes that are relatively independent of the influence of linguistic processing.

Attention that covers letters is necessary for the left-lateralization of an early print-tuned ERP in Japanese hiragana

“…In contrast to our previous study with the same conditions except for task-relevancy (Okumura et al, 2014), the present study found a left-lateralized print-tuned response at 130-170 ms post-stimulus when the constituent characters were closely spaced. Moreover, unexpectedly, we found an enhanced early occipital ERP for words before 100 ms post-stimulus.…”

“…Although an effect of spacing on leftlateralized N170 has not been studied previously, the print-tuned N1 in our former study was insensitive to this manipulation (Okumura et al, 2014). However, spacing has been shown to influence visual word processing and the neural activities of the VWFA (e.g., Cohen et al, 2008;Risko et al, 2011), a possible neural generator of the print-tuned N170 (e.g., Brem et al, 2006Brem et al, , 2009.…”

“…The purpose of the present study was to test whether attention to print stimuli is necessary for N170 left-lateralization in Hiragana script by using the same stimuli and the presentation condition as in the study by Okumura et al (2014). The critical difference was that participants detected infrequent blue stimuli (targets) among frequent black stimuli (nontargets) in the present study; such a task requires participants to discriminate or attend to color of print stimuli.…”

“…However, in our previous study, we failed to find N170 leftlateralization for Hiragana strings when participants were asked to detect a change in the color of the fixation under rapid stimulus presentation. More specifically, Hiragana words and nonwords elicited larger occipito-temporal N1 than symbols equally at left and right hemisphere sites (Okumura et al, 2014). This result suggests the absence of, or lesser engagement of, early phonological mapping under a condition in which attention to print stimuli are highly restricted, and it raises the possibility that early phonological mapping processes are not necessarily automatic.…”

“…The N170 is generally considered to reflect visual/orthographic processing; while modulations of its leftlateralization related to phonological processes have also been indicated. However, in our previous study, N170-like response to Hiragana strings lacked left-lateralization when the stimuli were completely taskirrelevant in rapid-presentation sequences [Okumura et al (2014). Early print-tuned ERP response with minimal involvement of linguistic processing in Japanese Hiragana strings.…”