New paper: Object files across eye movements, evidence from corrective saccades

When you try to reach for your favorite coffee mug, you introspectively know that in some instances you miss, get clumsy and accidently knock it over. However, you also know that in some cases you miss, but manage to correct your mistake and save face before your colleagues (an ‘I meant to do that’ moment). This occurs because motor systems are inherently imprecise, but can offset for these imperfections by updating movements whilst they are being executed. Similarly, whenever the eyes move, the don’t do so perfectly. The visual system is capable of correcting for these imperfections to an impressive extent. The visual system is so good at this, that we don’t even notice that we are correcting errors in the first place. Briefly put, corrective eye-movements are broadly categorized in two types, motor corrections and visual corrections, based on the nature of the signal that led to the correction.

In the current study we have investigated one type of error correction in particular, visual corrections. Visual corrections may occur when the visual system has determined that the object that was to be fixated after the eye-movement is now, in fact, not being fixated. In other words, if you expect to have your gaze centered on a particular object after an eye movement, and you determine that is not the case, a visual correction will follow suit. However, prior to this study, we knew relatively little on how visual corrective saccades are influenced by the familiarity of the object that is being corrected to.

The results of this study show that familiar (previously fixated) objects are corrected to significantly faster than novel objects. The direction of these results are illustrated above. The study also shows that this effect was not present for objects that shared the same features, at a different spatial location. Furthermore, in our third experiment we show that correcting your gaze to a familiar location is also significantly faster than to novel locations. In summary, these results indicate that visually guided corrective saccades are facilitated by previously fixated information, an interplay between feature information and spatial information.

 

Schut, M.J., Fabius, J.H., Van der Stoep, N., & Van der Stigchel, S. (in press) Object files across eye movements: Previous fixations affect the latencies of corrective saccades. Attention, Perception & Psychophysics. [pdf will be available upon publication]