Figure 1.

(a) Setup and bowls position for the delay of gratification test. The dog refrains from selecting the accessible LQR and waits for the HQR, which enters the enclosure after a certain delay. (b) Design and location of the bowls for the reversal learning test. The dog selected the metal bowl by approaching and touching it. Immediately thereafter, the experimenter, hidden behind the curtain, lifted the bowl to show whether it contained the reward.