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

What is it about?

It is well known that dogs can solve numerical discriminations between two amounts of food, choosing to eat from the plate offering the larger reward. This may refer to a spontaneous tendency, as it is advantageous to obtain the larger quantity with the less effort. However, most of research was conducted on companion dogs that were not used to experimental procedures, and thus might not immediately react to the experimental setting. The present study shows that, for the aforementioned preference to emerge, dogs must have had at least one experience in the experimental setting. Dogs were tested in two numerical discriminations (i.e., 2vs4 or 1vs8) in which they could choose to approach one of two plates. However, dogs were not allowed to eat the reward from the chosen plate, but always obtained one single piece of a different food, irrespective of their choice. Despite never experiencing a difference in the reward eaten, dogs successfully chose the plate with the larger quantity. This may indicate a motivational bias toward the larger food quantity that can bear relevant ecological value. However, dogs’ very first choice was at chance level, and was modified in subsequent trials. This may be due to the fact the dogs naïve to the task reached optimal attentional and motivational levels only after being exposed to the task.

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