Abstract
The ease with which a written word is processed depends on where the eyes initially fixate it. The optimal viewing position (OVP) is at the center of words, or slightly to the left of it. When the eyes initially fixate on this position, as compared to on a word's extremes, words are identified faster and more accurately, and are less likely to be refixated (OVP effects), whereas initial-fixation durations are longer (the inverted-OVP effect). These effects are typically explained as a combination of a central bias, due to the rapid drop-off of visual acuity from the center of the fovea, and a slightly-leftward bias, due to language-related constraints. We investigated whether these biases also characterize object processing. Although several studies indeed suggest there is a central OVP for objects, previous results are equivocal. Therefore, we examined whether (inverted) OVP effects exist for object processing, and if so, to what extent they differ from the ones typically observed for word processing. We carried out an object- versus word-naming task, and manipulated the location of the stimulus relative to a previously-displayed fixation dot. As a consequence, participants initially fixated different parts of the stimulus. To facilitate comparison between the two stimulus types, line drawings were scaled such that their width matched the width of the corresponding written word. We found that participants made less refixations, and showed longer initial-fixation durations, when their eyes initially fixated at the center, regardless of stimulus type. This confirms that both word- and object-processing are more efficient when the location of the eyes allows maximal visual-information uptake. However, both effects were weaker for pictures than for words. Furthermore, within-stimulus refixations showed a larger leftwards bias in words than in objects, suggesting additional language-related constraints for word processing. We will also discuss alternative, visual explanations.
Meeting abstract presented at VSS 2014