Eyes over stomach: companion dogs choose the larger quantity by sight, irrespective of the actual reward eaten

Abstract

Domestic dogs tested in a free-choice task between two sets of food prefer that of a larger quantity. A recent study pointed out the critical role of the first trial. Dogs succeeded only after being allowed at least once to eat the selected food. Here we explore the importance of the actual experience of consuming the selected reward on dogs’ capability to redirect their choice to solve numerical discriminations. Dogs tested in the 2 vs 4 and 1 vs 8 comparisons could never consume the quantity selected but always obtained a single dogs’ treat. Despite never experiencing a difference in the eaten quantity, dogs discriminated between the two sets, preferring the larger. Whereas they behaved at chance at first choice, they successfully redirected their preference toward the larger set already on their second trial. We discuss our results in terms of motivational biases toward the larger quantity that can bear relevant ecological value.