Fixation location effects on fixation durations during reading: an inverted optimal viewing position effect

Abstract

Previous research has found that words are identified most quickly when the eyes are near their center (the Optimal Viewing Position effect). A study was conducted to determine whether this same phenomenon is observed during reading, as revealed by a relationship between fixation position in a word and the duration of the fixation. An analysis of three large existing corpora of eye movement data, two from adults and one from children, showed a surprising inverted Optimal Viewing Position curve: mean fixation duration is greatest, rather than lowest, when the eyes were at the centers of words. From this phenomenon, we suggest an alternative explanation to the fixation duration trade-off effect in word refixations [O'Regan & Lévy-Schoen, Attention and performance XII: the psychology of reading (1987)]; the phenomenon also contradicts expectations of both oculomotor and cognitive theories of eye movement control. Attempts to test alternative explanations led to the discovery of another phenomenon, the Saccade Distance effect: mean fixation durations vary with the distance of the prior fixation from the currently-fixated word, being longer with greater distances. The durations of fixations in reading are complexly determined, with influences both from language and perceptual/oculomotor levels.

The potential contribution of preplanned refixations to the preferred viewing location

“…The probability of the eyes initially fixating a given letter position is estimated by the relative frequency in the corpus. These data exhibit the typical properties of the landing position distributions that have been reported by other researchers (e.g., McConkie et al, 1988;Rayner, 1979;Vitu et al, 2001). First, the curves for shorter words are flatter than those for longer words (the mode of the curve is more easily distinguished for longer words); second, the majority of the probability mass is distributed over the first half of the word.…”

Tracking the mind during reading: The influence of past, present, and future words on fixation durations.

“…(2) These cases immediately trigger a new saccade program. Interestingly, the IOVP effect appears to be largely independent of word frequency (i.e., the curve is simply elevated for low-frequency words; Nuthmann et al, 2005;Rayner, Sereno, & Raney, 1996;Vitu et al, 2001) and, therefore, represents a comparatively confined contribution of oculomotor errors to fixation durations. …”

Reading polymorphemic Dutch compounds: Toward a multiple route model of lexical processing.

“…Whatever the disadvantages of our methodology may be, the pattern of results that we have obtained and reported either in the body of the paper or in Appendix 1, dovetails perfectly with many of the results obtained in the literature for sentential reading, such as visuo-oculomotor effects (cf., e.g., O'Regan et al, 1994;Rayner, 1998;Vitu, McConkie, Kerr & O'Regan, 2001), effects of compound length and frequency, as well as of constituent frequencies (cf., e.g., Andrews et al, 2004;Duñabeitia, Perea & Carreiras, 2007;Hyönä & Pollatsek, 1998;Hyönä et al, 2004;Juhasz et al, 2003;Taft & Forster, 1976), and effects of orthographic n-grams (reported in Appendix 1, cf., e.g., Lima & Inhoff, 1985). Furthermore, in a recent sentential reading study (Kuperman, Bertram & Baayen, 2008), in which Finnish compounds were embedded in context, a highly similar pattern of results was observed, including early effects of compound frequency, left constituent frequency and family size, later and weaker effects of right constituent frequency and family size, interactions between morphological predictors, as well as longitudinal experimental effects.…”