Comment on "Differential sensitivity to human communication in dogs, wolves, and human infants".

Topál et al. (Reports, 4 September 2009, p. 1269) reported that dogs' sensitivity to reading and using human signals contributes to the emergence of a spatial perseveration error (the A-not-B error) for locating objects. Here, I argue that the authors' conclusion was biased by two confounding factors: the use of an atypical A-not-B search task and an inadequate nonsocial condition as a control.