Can your horse remember which bucket you hid the carrot under?

01 Jun 2015

 

A recent study conducted by Italian researchers showed horses can use observed human activity to solve a delayed task more accurately than previously thought. In this particular experiment they found horses changed their problem-solving strategy over time from a precision based approach to a speed based approach.

The study involved two people, a handler and an experimenter. Each horse was presented by a handler to three buckets set out an equal distance away. The horse then observed an experimenter hide a carrot under one of the buckets. The handler turned away so as not to see the experimenter hide the carrot. This is because if the handler knew the answer they might give it away with unconscious body language (also known as the Clever Hans effect). The experimenter then ducked behind a wooden wall and the horse was released ten seconds later, thus accurately finding the carrot required some measure of short-term memory. Like any good study there was also a control group of horses. The control group of horses did not see the experimenter hide the carrot. Each horse undertook the activity ten times. The first five times, the experimental horses (those who had seen the experimenter hide the carrot), chose the bucket with the carrot first significantly more often than the control group horses. However, the experimental group horses also took significantly longer to get to the carrot. The researchers hypothesise this is because the horses had to stop and recall from their short-term memory the movement of the experimenter.

By the time the horses in the experimental group got to about their sixth trial, they began to show a change of strategy, they no longer went for the specific carrot concealing bucket but rather knocked over all the buckets as quickly as possible. Notably they seemingly had a preference to initially knock over the bucket that last held the carrot. This was no help to them because a different bucket was randomly chosen each time. Using this strategy horses were less accurate but found the carrot just as quickly as the control group did.

Interestingly the control group did not show any preference for the bucket that had previously had the carrot in it. The researchers do not know why this is.

The speed versus accuracy trade-off has been previously studied and is known as foraging theory. Foraging theory states that animals will obtain the most energy (food), for the minimum expenditure of energy and in the least amount of time. If being more accurate leads to the outcome of a greater amount of food in the same or slightly longer amount of time then it could be predicted that the horse might continue to think more carefully about which bucket he chooses. In this scenario, thinking about which bucket to choose is apparently more costly energy and time wise than knocking them over as fast as possible.

Reference

Lovrovich, P., Sighieri, C., & Baragli, P. (2015). Following human-given cues or not? Horses ( Equus caballus ) get smarter and change strategy in a delayed three choice task. Applied Animal Behaviour Science, 166, 80-88.

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