Not fixating at the line of text comes at a cost

The Preferred Viewing Location in Top-to-Bottom Sentence Reading

The preferred viewing location (PVL) is a robust finding in research on reading that when fixating on a word during normal sentence reading, readers tend to land slightly to the left of the center of the word. This is in contrast to the optimal viewing location (OVL) in single word recognition, which falls at the center of the word. The current study outlines the history of the PVL in eye-tracking since Rayner's 1979 original study, documenting the origins of these conflicting theoretical explanations. In addition, a new study is reported examining whether the PVL can be attributed solely to oculomotor error or a processing advantage by using an experimental manipulation that separates tracking direction (left-to-right reading) and landing position (left-to-right within a word). Sentences were presented to participants from the top to the bottom of a computer screen with one word per line while eye movements were recorded. In this presentation format, readers continued to land to the left of center, suggesting that the PVL in normal reading is not solely due to oculomotor error.

On the optimal viewing position for object processing

Numerous studies have shown that a visually presented word is processed most easily when participants initially fixate just to the left of the word's center. Fixating on this optimal viewing position (OVP) results in shorter response times and a lower probability of making additional within-word refixations (OVP effects), but also longer initial-fixation durations (an inverted-OVP or I-OVP effect), as compared to initially fixating at the beginning or the end of the word. Thus, typical curves are u-shaped (or inverted-u-shaped), with a leftward bias. Most researchers explain the u-shape in terms of visual constraints, and the leftward bias in terms of language constraints. Previous studies have demonstrated that (I)-OVP effects are not specific to words, but generalize to object viewing. We further investigated this by comparing the strength and (a)symmetry of (I-)OVP effects for words and objects. To this purpose, we gave participants an object- versus word-naming task in which we manipulated the position at which they initially fixated the stimulus (i.e., a line drawing or the written name of an object). Our results showed that object viewing, just as word viewing, resulted in u-shaped (I-)OVP curves. However, the effect was weaker than for words. Furthermore, for words, the curves were biased to the left, whereas they were symmetrical for objects. This might indicate that part of the (I-)OVP effect for words is language specific, and that (I-)OVP effects for objects are a purer measure of the effect of visual constraints.