Taxi vs. Taksi: On Orthographic Word Recognition in the Left Ventral Occipitotemporal Cortex

Abstract

The importance of the left occipitotemporal cortex for visual word processing is highlighted by numerous functional neuroimaging studies, but the precise function of the Visual Word Form Area (VWFA) in this brain region is still under debate. The present fMRI study varied orthographic familiarity independent from phonological-semantic familiarity by presenting orthographically familiar and orthographically unfamiliar forms (pseudohomophones) of the same words in a phonological lexical decision task. Consistent with orthographic word recognition in the VWFA, we found lower activation for familiar compared to unfamiliar forms, but no difference between pseudohomophones and pseudowords. This orthographic familiarity effect in the VWFA differed from the phonological familiarity effect in left frontal regions, where phonologically unfamiliar pseudowords led to higher activation than phonologically familiar pseudohomophones. We suggest that the VWFA not only computes letter string representations but also hosts word specific orthographic representations. These representations function as recognition units with the effect that letter strings, which readily match with stored representations lead to less activation than letter strings which do not.

Pseudohomophone effects provide evidence of early lexico‐phonological processing in visual word recognition

“…Finally, Kronbichler et al (2007) reported higher AG activity to pseudohomophones compared to pseudowords in a visual phonological decision task. These findings add further support to the idea that AG/SMG activity is involved in whole-word processing and furthermore that pseudohomophones probably activate their phonologically identical base words and thus signal lexical access.…”

“…Further support for an involvement of these areas in phonological processing is provided by a number of studies (e.g., Fiebach et al, 2002;Mechelli et al, 2007;Rumsey et al, 1997;Carreiras, Mechelli, and Price, 2006;Carreiras et al, 2007;Owen et al, 2004;Posner and Raichle, 1994;Ischebeck et al, 2004;Dietz et al, 2005, Borowsky et al, 2006 and also from imaging studies using pseudohomophones in visual word recognition reporting left and right inferior frontal gyrus activity (pars opercularis and triangularis) for pseudohomophones when compared to pseudowords (e.g., Edwards et al, 2005;Kronbichler et al, 2007).…”

The left occipitotemporal system in reading: Disruption of focal fMRI connectivity to left inferior frontal and inferior parietal language areas in children with dyslexia

“…During fMRI acquisition, participants performed a phonological lexical decision task in which they had to decide whether a visually presented stimulus sounded like a real word or not (Kronbichler et al, 2007;Van der Mark et al, 2009; Additionally, 65 null events (fixation cross only) were presented. In the event-related design, the stimuli were presented for 700 ms with an interstimulus interval (ISI) of 2550 ms during which a fixation cross was shown.…”

Early emergence of deviant frontal fMRI activity for phonological processes in poor beginning readers

“…In German visual rhyming tasks, rhyming word pairs usually have an increased visual similarity compared to nonrhyming pairs, with the consequence that pure visual matching strategies allow to solve rhyming tasks, without phonological processing. Other paradigms used to study phonological processes are word vs. pseudoword and/or pseudohomophone reading (Kronbichler et al, 2007;Miellet and Sparrow, 2004;van der Mark et al, 2009). Yet, poor beginning readers may have difficulties to distinguish between words and pseudohomophones due to the lack of orthographic knowledge.…”