Dolphin Hear, Dolphin Do

They say that imitation is the sincerest form of flattery, but in fact it’s an important method of learning. When young children play house or pretend to talk on the phone, for example, they’re trying out and learning important cultural and social behaviors. Additionally, scientists think the ability to imitate may be required for higher, human-specific cognitive abilities, such as language and theory of mind (understanding what others may be thinking). As we’ve seen before, scientists often study cognitive abilities of animals in order to better understand those abilities in humans. We can study imitation in animals because, importantly, imitation doesn’t require the use of language.

7376861816_2b39b2b644_nInterestingly, dolphins appear to be very good at imitating the sounds and motions of other dolphins and of humans. This finding surprised scientists because dolphins and humans are only very distantly related. Scientists suspect that dolphins’ ability to imitate is the result of convergent evolution (different species evolve the same characteristic or ability, independent of each other), rather than the very early evolution of this ability by a common ancestor of humans and dolphins. By studying imitation in dolphins, we can gain some insight into how and why humans may have also developed this ability.

However, it is possible that in dolphins, imitation isn’t a conscious copying behavior (like it is in humans). Rather, their imitation could be due to an automatic process called “response facilitation”. Put simply, response facilitation is when an animal that senses another animal make a familiar movement becomes more likely to make that movement itself. This occurs because there is a strong connection in the animal’s brain between a movement and the sound made by that movement, due to all of the experience the animal has of making that movement itself and hearing the corresponding sound. In response facilitation, the animal’s response is less conscious and deliberate, and is instead more like a reflex.

In order to investigate the nature of dolphins’ imitation ability, Jaakkola et al. (2013) studied the perceptual information used by a blindfolded dolphin when imitating the motions of another dolphin and a human. Specifically, the researchers studied when the blindfolded dolphin relied on sounds and on echolocation to determine the motions made by the other dolphin and the human.

Jaakkola et al. assumed that a dolphin would be very familiar with the sounds made by a dolphin doing certain motor actions (such as blowing bubbles, spinning in a circle, and waving). Therefore, sound alone should be sufficient for the blindfolded dolphin to figure out the motion that another dolphin (the dolphin “model”) is making, in order to imitate it. This does not rule out the possibility of response facilitation, which is where the human “model” comes in: a dolphin should be much less familiar with the sounds made by a human doing certain motor actions. Thus, it should rely more on echolocation (which provides information about the position of the human model) to figure out the motion that the human model is making.

8191515204_edd9e9199e_nThe use of echolocation to imitate humans would indicate that dolphins’ imitation is not due to response facilitation for a couple reasons. First, a dolphin’s sense of echolocation, unlike its other senses, is not always on: the dolphin has to decide to use echolocation. The use of echolocation, then, suggests that the dolphin is consciously trying to determine the human’s movements, rather than using response facilitation. Second, dolphins can’t use echolocation to gauge their own movements, so that information isn’t connected to that movement in the dolphin’s brain. Thus, echolocation information for a particular movement shouldn’t automatically trigger that same movement in the imitating dolphin.

Jaakkola et al. trained a dolphin to imitate the motions of another dolphin and a human, while blindfolded (which is an incredible feat in and of itself!). They found that the dolphin was able to imitate both the other dolphin and the human more accurately than chance, and that the dolphin was equally accurate when imitating the other dolphin and the human. However, the dolphin used echolocation significantly more when he imitated the human than when he imitated the other dolphin.

This result indicates that imitation by dolphins is not due to response facilitation, but is instead more like the imitation ability of humans. The fact that the dolphin was able to use hearing and echolocation in varying proportions also shows how flexible and intentional their imitation can be: they can use different sources of information in order to imitate, and they can select the most appropriate information sources depending on the situation.

The Dolphin Research Center, where this study was carried out, made some great summary videos of this research: here’s one of the study where they trained the dolphin to imitate another dolphin while blindfolded, and here’s one of the study described above.

Source:

Jaakkola, Kelly, et al. “Switching strategies: a dolphin’s use of passive and active acoustics to imitate motor actions.” Animal cognition (2013): 1-9.

Advertisements

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s