Capacity of bottle-nosed dolphins for generalization based on a relative sign.

Using a new modification of a previously proposed method in the bottle-nosed dolphin, a conditioned reflex was developed and consolidated to a relative spatial sign, namely the choice always of the left out of two identical objects under conditions of constant change of the position of this pair of stimuli against the background of one of the sides of the pen. The specialization was checked by means of the presentation of the pair of stimuli through various changes of the surrounding setting, including the discordance of external landmarks, as well as by the means of the presentation of the stimuli. Then the objects were replaced by others (12 pairs of stimuli) sharply differing from the initial stimuli in form, size, material, etc. The maintenance of appropriate choice, including with change in the medium of presentation of the stimuli) attested to the capacity of the dolphins to abstract and generalize on the basis of a relative sign, i.e., of abstraction and generalization in the "to the left-to the right in general" choice of two objects.