A functional role of visual working memory-related saccade biases?

Visual working memory (VWM) can influence oculomotor control. Hollingworth & Luck (2009) showed that corrective saccades can be biased by a memorized feature: attention and gaze shift away from the original target and towards a distractor matching the content of VWM. This may simply reflect a poor separation of different mechanisms. Alternatively, could VWM-related ocular biases have a functional role? The attentional shift coupled with saccade biases may refresh the content of VWM by updating it to the last fixated item. In this case, the magnitude of saccade correction biases also might depend on VWM task demands. 20 observers had to memorize a color hue that was tested against another hue from the same (Difficult condition) or a different color category (Easy condition). Prior to the test phase, they performed a saccade task where the position of the target changed in a gaze-contingent manner. Concurrently, the color of a neighboring distractor changed (or not) to a color (dis)similar to the one maintained in VWM. VWM performance was higher in the Easy than in the Difficult condition, indicating a successful manipulation of task difficulty. Independently of task difficulty, saccade corrections were biased more towards the distractor when it matched VWM content compared to when it did not, replicating previous findings. Most importantly for our research question, saccade corrections towards the distractor were more frequent in the Difficult compared to the Easy condition, indicating an influence of task difficulty on the attentional bias. Furthermore, VWM performance in the Easy condition was higher when saccades were biased towards the distractor rather than towards the target, suggesting a role of corrective saccades in the updating of VWM. Overall, our results indicate a potential functional role of VWM-related saccade biases since they increase with task difficulty and can facilitate VWM performance.