Stats Fact 3
Can an elephant really interpret human pointing?
Photo by skuarua
What’s the evidence?
You might have seen this study, by Anna Smet and Richard Byrne, in the news. Captive African elephants were tested to see if they could interpret human pointing to find hidden food. The elephants had to choose between two containers of food – so there was a 50% chance they would be right if they were guessing.
The elephants were tested with different ways of “pointing”, including the ones in this diagram:
One way included only using the eyes (gaze only). The experimenters also included a condition with no pointing at all. They called this “no point control”.
What were the results like?
The elephants did a number of trials with each different way of pointing, so the researchers worked out the percentage of times that an elephant was correct. If elephants were guessing, the percentage correct would be 50%.
Our graph of the study results shows the mean percentage correct for the elephants for each type of pointing. The lines from the squares are some more technical detail; they show uncertainty.
What does the graph tells us?
- The results for no pointing are close to the red line – the mean percentage we would expect if the elephants were guessing.
- The results for subtle ways of pointing – forward cross body and elbow cross body – are also close to the red line.
- The results for clearer ways of pointing are to the right of the red line – the elephants are doing better than chance guessing.
The researchers interpreted this pattern of results to mean that the elephants understood the experimenter’s communicative intent.
How convincing is the evidence?
This looks like a good study. It’s a bit more complicated that my description here, but you can check it out yourself, and even look at videos of the experiment. Here’s just a few of the reasons:
- A good feature of the study was that the order of testing of the elephants with the different ways of pointing was randomized. If the researchers hadn’t done this, we might not be able to untangle possible learning effects over time from the effects of the different ways of pointing.
- The results are coherent; the elephants did no better than chance for control and the more definitive the point the better the elephants did.
- The researchers thought very carefully about a lot of fine detail. This type of study is tricky – there could be many subtle ways that the elephants could be given unintentional cues. For example, the elephant’s handler knew where the food was. Another concern is where the researcher stood: between the containers? next to the container with the food? next to the empty container?
How does this compare to babies?
On average, elephants were correct 68% of the time when a whole arm ipsilateral point was used. (“Ipsilateral” means “on the same side of the body”.) The researchers tell us that one-year-old children get 73% right on average on this type of task.
What’s the theory?
The researchers described a couple of different explanations of why elephants might be able to interpret pointing as communication.
- One theory is that this ability has evolved as elephants became domesticated. The evidence is that domesticated animals do better at the pointing task than non-domesticated animals.
- An alternative view is that animals already sensitised to cues from humans tend to be more suitable for domestication.