How undistorted spatial memories can produce distorted responses

Reproducing the location of an object from the contents of spatial working memory requires the translation of a noisy representation into an action at a single location—for instance, a mouse click or a mark with a writing utensil. In many studies, these kinds of actions result in biased responses that suggest distortions in spatial working memory. We sought to investigate the possibility of one mechanism by which distortions could arise, involving an interaction between undistorted memories and nonuniformities in attention. Specifically, the resolution of attention is finer below than above fixation, which led us to predict that bias could arise if participants tend to respond in locations below as opposed to above fixation. In Experiment 1 we found such a bias to respond below the true position of an object. Experiment 2 demonstrated with eye-tracking that fixations during response were unbiased and centered on the remembered object’s true position. Experiment 3 further evidenced a dependency on attention relative to fixation, by shifting the effect horizontally when participants were required to tilt their heads. Together, these results highlight the complex pathway involved in translating probabilistic memories into discrete actions, and they present a new attentional mechanism by which undistorted spatial memories can lead to distorted reproduction responses.