Mislocated fixations during reading and the inverted optimal viewing position effect

• Published in: Vision research (Oxford) Vol. 45; no. 17; pp. 2201 - 2217
• Main Authors: Nuthmann, Antje, Engbert, Ralf, Kliegl, Reinhold
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier Ltd 01.08.2005; Elsevier Science
• Subjects: Adolescent; Adult; Aged; Aged, 80 and over; Algorithms; Biological and medical sciences; Cognition - physiology; Fixation, Ocular - physiology; Fundamental and applied biological sciences. Psychology; Humans; Language; Middle Aged; Mislocated fixations; Models, Biological; Optimal viewing position; Production and perception of written language; Psychology. Psychoanalysis. Psychiatry; Psychology. Psychophysiology; Reading; Saccades - physiology; Saccadic errors; Time Factors; Optimal viewing position; Reading; Saccadic errors; Mislocated fixations; Human; Fixation; Optimality condition; Mathematical model; Saccadic eye movement
• ISSN: 0042-6989; 1878-5646
• DOI: 10.1016/j.visres.2005.02.014

Refixation probability during reading is lowest near the word center, suggestive of an optimal viewing position (OVP). Counterintuitively, fixation durations are largest at the OVP, a result called the inverted optimal viewing position (IOVP) effect [Vitu, McConkie, Kerr, & O’Regan, (2001). Vision Research 41, 3513–3533]. Current models of eye-movement control in reading fail to reproduce the IOVP effect. We propose a simple mechanism for generating this effect based on error-correction of mislocated fixations due to saccadic errors. First, we propose an algorithm for estimating proportions of mislocated fixations from experimental data yielding a higher probability for mislocated fixations near word boundaries. Second, we assume that mislocated fixations trigger an immediate start of a new saccade program causing a decrease of associated durations. Thus, the IOVP effect could emerge as a result of a coupling between cognitive and oculomotor processes.