Following human-given cues or not? Horses (Equus caballus) get smarter and change strategy in a delayed three choice task

tTo date, horses have seemed capable of using human local enhancement cues only when theexperimenter remains close to the reward, since they fail to understand the communicativemeaning of the human as momentary local enhancement cue (when the human is notpresent at the moment of the animal’s choice). This study was designed to analyse theability of horses to understand, remember and use human-given cues in a delayed (10 s)three-choice task. Twelve horses (experimental group) had to find a piece of carrot hiddenunder one of three overturned buckets after seeing the experimenter hide it. The resultswere then compared with those of a control group (twelve horses) that had to find thecarrot using only the sense of smell or random attempts. At the beginning, the experimentalhorses made more correct choices at the first attempt, although they took more time tofind the carrot. Later the same horses were less accurate but found the carrot in less time.This suggests that the value of the proximal momentary local enhancement cues becameless critical. It seemed, in fact, that the experimental and control group had aligned theirbehaviour as the trials proceeded. Despite this similarity, in the second half of the trials,the experimental group tended to first approach the bucket where they had found thecarrot in the immediately preceding trial. Our findings indicate that horses are capable ofremembering the location of food hidden by the experimenter after a delay, by using thehuman positioned close to the target as valuable information. The same horses are alsocapable of changing their decision-making strategy by shifting from the accuracy inferredfrom human given cues to speed. Therefore, horses are able to decide whether or not to usehuman given-cues, depending on a speed-accuracy trade-off.