If you see someone point to something over your head you generally look upwards. This is because humans understand that this type of referential communication is used to draw our attention to an object or place that the informer is attending to (we are extremely susceptible to this – the direction of human attention can even be influenced by the mention of a specific word). These types of gestural cues are frequently used by humans; children are able to learn about them from an early age and there is growing evidence that non-human animals are able to use pointing cues as well.
TV programs from our childhood such as Lassie and Flipper continually suggest that animals are good at understanding and following human cues – but what information can they actually use? Unsurprisingly, most of the work in this area has focused on domesticated animals, particularly dogs, and the evidence suggests that they are able to use human gestural cues to make choices about objects in their environment. In contrast, our closer relatives, the apes, tend to perform poorly on this type of task. This has led to the suggestion that domestication may play a crucial role in the use of human communicative gestures by animals. The hypothesis suggests that during domestication animals that were more docile or more responsive to humans would be permitted to breed. It is likely that responsiveness to specific human cues may have played a key role in selection.
However, there is also some evidence that animals as disparate as elephants and seals are able to use human cues. The animals in these experiments generally had extensive experience with humans, which gives rise to the idea that the ability to use human gestural cues may not be a result of selection during domestication but could rather depend on an individual animal’s experience of humans (and therefore their experience of human gestural cues outside an experimental context). This is supported by research undertaken by Lyn and colleagues (2010) who showed that socio-linguistically raised chimpanzees are able to use gestural cues better than lab raised chimps.
Raphaelle Malassis and Fabienne Delfour (University of Paris) probed this idea further in a recent paper published in the Psychonomic Society’s journal Learning and Behavior. They wanted to investigate whether sea lions, a species that has not been domesticated but, in the case of show animals, has a vast experience of, and interactions with, humans, are able to use human gestural cues to solve a number of tasks. If this were the case then we would expect that learning, rather than selection is controlling the animal’s ability to use human gestural cues.
Malassis and Delfour presented the sea lions with three different tasks. In the first task the animals had to choose between two objects. If the sea lions chose the correct object (the one that the human was directing attention to) they were rewarded with a favorite food. The animals were presented with conditions that varied the types of referential cue. This ranged from cues that the animals were likely to have observed many times, having spent extensive time with humans, such as pointing with the hand in a variety of ways and gazing in the direction of the correct object, to more unusual communicative cues such as pointing with the foot or elbow. The sea lions performed at high levels in this task, with some animals responding correctly on their very first exposure to the stimulus conditions. One animal struggled with the more unusual gesture but the others performed well throughout.
A second study investigated whether the sea lions were able to locate a specific object when more than one object was on the same side as the point. This study tested whether the sea lions were using the point to indicate an approximate area (to the left or right of the experimenter), or whether they could use the specific point as a cue. The results showed that the animals could. They were able to choose either the close or far stimulus on both the left and right hand side depending on the specifics of the point. The final study showed that the sea lions were even able to use pointing gestures to locate hidden objects (though one animal did need some additional training).
Taken together, this set of studies tells us that the ability of sea lions to use human gestural cues is comparable and, in some conditions, superior to that observed in dogs—the sea lions were able to use the elbow point cue, a condition which dogs have been reported to fail. The findings suggest that exposure to human communicative cues is likely to control an animal’s ability to use them. Further, it suggests that selection for this ability, for example during domestication, is not necessary for the successful use of human gestures.
Therefore, spending quality time with us may be key for our pet dogs to know whether we’re pointing to the treat jar or the leash.