Ideal observer model.

(A) The visual working memory decoding model, in which egocentric and allocentric estimates are integrated depending on their respective reliabilities. While precision of the egocentric component is set by Pego, the allocentric precision is determined by two parameters: the peak precision obtained when landmark and target are aligned (Amax), and a scale parameter describing how quickly allocentric precision declines with increasing landmark-target distance (Ascale). The model further incorporates a fixed probability of lapsing (p(lapse); responding at random relative to the target), giving four free parameters in total. (B) Precision of egocentric (blue) and allocentric (green) estimates shown as a function of distance from the landmark. While egocentric precision is constant, the precision of allocentric information decreases exponentially as the distance increases. The precision of the integrated estimate (red) is equal to the sum of precisions of the individual components.