Reading sentences of uniform word length \u2013 II: Very rapid adaptation of the preferred saccade length

Michael G Cutter,Denis Drieghe,Simon P Liversedge

doi:10.3758/s13423-018-1473-2

Abstract

In the current study we investigated whether readers adjust their preferred saccade length (PSL) during reading on a trial-by-trial basis. The PSL refers to the distance between a saccade launch site and saccade target (i.e., the word center during reading) when participants neither undershoot nor overshoot this target (McConkie, Kerr, Reddix, & Zola in Vision Research, 28, 1107-1118, 1988). The tendency for saccades longer or shorter than the PSL to under or overshoot their target is referred to as the range error. Recent research by Cutter, Drieghe, and Liversedge (Journal of Experimental Psychology: Human Perception and Performance, 2017) has shown that the PSL changes to be shorter when readers are presented with 30 consecutive sentences exclusively made of three-letter words, and longer when presented with 30 consecutive sentences exclusively made of five-letter words. We replicated and extended this work by this time presenting participants with these uniform sentences in an unblocked design. We found that adaptation still occurred across different sentence types despite participants only having one trial to adapt. Our analyses suggested that this effect was driven by the length of the words readers were making saccades away from, rather than the length of the words in the rest of the sentence. We propose an account of the range error in which readers use parafoveal word length information to estimate the length of a saccade between the center of two parafoveal words (termed the Centre-Based Saccade Length) prior to landing on the first of these words.

Highlights

During reading saccadic eye movements allow readers to extract high acuity visual information from multiple successive points in a sentence (Rayner, 1998)
To determine whether our manipulation led to an adaptation in the preferred saccade length (PSL) we constructed a linear mixed-effect model in which the initial landing position within a word relative to the word center was our dependent variable, while the length of word the eyes landed on, sentence uniformity, and launch site from the center of the word were treated as fixed factors
We presented participants with sentences that varied in their word length in an unblocked design

Summary

Introduction

During reading saccadic eye movements allow readers to extract high acuity visual information from multiple successive points in a sentence (Rayner, 1998). In English, saccades are argued to be typically targeted towards the center of an upcoming word, maximizing the number of a word’s letters that fall in high acuity vision, thereby increasing processing efficiency. McConkie, Kerr, Reddix, and Zola (1988) examined the distribution of initial fixation positions within a word as a function of the distance of the site from which a saccade had been launched, finding that the eye tended to land in the center of a word when the saccade was launched from seven characters away from that word’s center. The second component is the level of error predicted to occur for each character of deviation between (a) the PSL, and (b) the distance between the launch site and the intended saccade landing position, with this being

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Conclusion