[PS-2.2] Sensitivity to word inversion and word length provides a window into reading procedures in typical and dyslexic readers

Ben-Yehudah, G. & Gilutz, Y.

Department of Education and Psychology, Open University of Israel

Proficient readers are slow, though surprisingly accurate, at reading upside-down text (word inversion effect, WIE). When a word is inverted, reading speed is influenced by string length (word length effect, WLE). In contrast, a frequently encountered word displayed in a standard orientation is recognized quickly irrespective of length. The purpose of this study was to test hypotheses related to reading procedures, using the emergence of a WLE as an indicator for a shift from a holistic-automatic procedure to an analytic-controlled procedure. To induce a WLE we rotated words by 180°, and examined the impact of inversion on the performance of two populations with different reading skills: adults with a history of developmental dyslexia and age-matched typical readers. Participants performed a naming and a semantic decision task in their native Hebrew language. In both tasks, we used high-frequency words and manipulated display orientation (standard, inverted) and word length (3-, 4-, 5-letters). As predicted, typical readers were not sensitive to word length when items were displayed in a standard orientation. Surprisingly, contrary to our prediction, dyslexics' pattern of performance was similar to that of typical readers for standard words. When inverted words were displayed, RTs in both groups increased considerably (the WIE) and a WLE emerged. Interestingly, in the inverted condition the dyslexic group was faster than typical readers at making a semantic decision for short words; whereas, they were slower than typical readers at naming long words. In order to distinguish between general-perceptual and linguistic explanations of the inversion effect, the participants also performed a classic mental rotation task. The results did not support a general-perceptual explanation of this effect. Assessing sensitivity to word inversion with respect to string length revealed interesting differences between dyslexic and typical readers. These differences provide new insights on the reading procedures used by each group.