Dolphin Curiosity: Knowledge for Knowledge’s Sake

You’ve just finished a delicious sushi dinner and you’re stuffed; you couldn’t possibly eat another bite. Still, when the diners next to you are served, you can’t help looking over, just to make sure that they, the other dolphins, aren’t getting a better meal.

That’s right, you’re a bottlenose dolphin, and you’re curious. Curious not because you’re going to do anything about it, but simply because you want to be sure that you haven’t missed out on anything. You want knowledge for knowledge’s sake, however painful it might be.

Humans often need to know certain things, even when finding out opens the doors to an unpleasant discovery. After the worker receives a raise, he can’t help poking around to see whether his coworker received a larger increase. After the shopper buys a large flat screen TV, she keeps looking at advertising circulars to see whether she paid too much. While our curiosity sometimes serves a clear purpose (perhaps that raise can still be renegotiated, maybe that TV can be returned), we often persist in our quest for potentially negative information even when it is too late to change anything, even after the raise has been formally accepted and the TV can no longer be returned. Research on human-decision-making suggests that we act this way because we find the uncertainty of “not knowing” to be uncomfortable. Finding out even the most-unpleasant truths can relieve us from ruminating obsessively over our suspicions, enable us to make sense of our missed opportunities, assist us in coming to terms with our past decisions, and ultimately allow us to regulate our moods in a healthy fashion.

But dolphins? The actions of nonhuman animals are not typically described in these terms. Rather, we find utilitarian explanations – a tangible benefit to compensate the animal for the energy and risk of exploration, a way in which the animal’s curiosity will improve its fitness or survival chances.

OMG, do you see what the Snorkersons are having for dinner?! (image credit: Peter Asprey)

Recently, though, a research team from Israel reported in the Journal of Economic Psychology on a clever experiment indicating that bottlenose dolphins (Tursiops truncatus) are much like humans in seeking knowledge for knowledge’s sake. The researchers studied a group of eight bottlenose dolphins at a “commercial sea enclosure” as they were fed over a seven-month period. The dolphins were fed meals of varying size five times a day, with all dolphins eating at the same time. The dolphins were fed from three separate rafts, with each dolphin assigned one of the rafts and summoned to the proper feeding location with a specific sound signal. During the study period, the researchers observed a total 1,250 dolphin feedings and made special note whenever a dolphin went to over to another raft to explore what other dolphins were being fed.

One of the researchers’ hypotheses was that, to the extent the dolphins sought out knowledge for knowledge’s sake (described in the paper as “Non-Instrumental Curiosity”), they would increase this behavior once their basic survival needs had been satisfied. The researchers were assisted in exploring this hypothesis by two factors: first, about halfway through the study, the dolphins were put on a diet, receiving approximately 15% less food per day on average for the remainder of the testing period, and second, during the latter portion of the experiment the dolphins’ sexual interactions increased markedly due to higher water temperatures and seasonal changes. (Note to self: watch out for pods of horny dolphins as the impacts of global warming become more severe.)

The researchers found that, over the course of the experiment, dolphins visited other feeding rafts 26% of the time (325 of 1,250 feedings). All dolphins visited other rafts, but the percentage of visits ranged from 11.3% to 37.9%, indicating individual differences in curiosity among dolphins. Because the dolphins managed to obtain food scraps on only three occasions (i.e., less than 1% of the time), the research team concluded that it wasn’t likely that the dolphins were using their explorations as a foraging strategy. Moreover, the researchers statistically analyzed the explorations and did not find correlations between the visiting behavior and the dolphins’ known social structure (that is, associations between mothers and calves, adolescent males and females, etc.). In short, there were no obvious benefits to the dolphins’ behavior, and the results supported the premise that they were visiting other feeding rafts out of Non-Instrumental Curiosity.

Hrmph... Next time let's put the researchers on a diet, and see how it impacts *their* behavior (image credit: Laaude at fr.wikipedia)

In addition, the researchers found that dolphins were significantly more likely to visit other rafts when they received larger meals, and that their overall curiosity level was much lower during the phase of the experiment when they were on a diet (they visited other rafts only 13% of the time when on a diet, compared to 38% of the time during the non-dieting phase). Further, during the dolphins’ more sexually active phase, they significantly decreased their exploratory behavior — they visited other rafts only 12% of the time during this phase, compared to 43% during the period when they were less sexually active. (Note though that, because there was a substantial overlap between the dieting and sexually active phases, it wasn’t really possible to separately tease out the relative impacts of these two factors.)

The researchers summarized their results as follows:

In this manuscript, we show that bottlenose dolphins as well, sometimes seek to increase their knowledge concerning food allocated to other dolphins in the group, even though such knowledge could not increase self-food availability. This search increases when own feed is augmented, and decreases when sexually engaged (a competing basic need to food and curiosity), suggesting that knowledge for knowledge’s sake emerges particularly when the organisms’ basic needs (e.g., food) have been satisfied, allowing higher-level psychological needs to emerge.

It seems to me that another way to look at Non-Instrumental Curiosity is that it may be an indication that dolphins are sensitive to inequity and that they possess a sense of fairness, and that it would be interesting to see further research into related cognitive realms, such as their capacity for altruism, empathy and self-awareness. While that may be the subject of future experiments and later AnimalWise posts, for now I’m kind of curious – where did you get all of that tasty looking mackerel?


ResearchBlogging.orgShani, Y., Cepicka, M., & Shashar, N. (2011). Keeping up with the Joneses: Dolphins’ search knowledge for knowledge’s sake Journal of Economic Psychology, 32 (3), 418-424 DOI: 10.1016/j.joep.2011.02.014.

Leave a comment


  1. I’m thinking there’s another influence on the dolphins’ expression of curiosity. When the water temperature and sexual activity go up, the ramped-up metabolism needs feeding–not a good time to have rations cut. How much energy is left for extras? I wonder why the experimenters chose to add that complication.

    Paul, I’ve recently finished reading Diana Reiss’s trade book on dolphin intelligence, a sort of scientific memoir, which came out about a month ago. In her experiments and unstructured behavioral observations, she deals with the topics of their “capacity for altruism, empathy, and self-awareness.” An interesting read. I’m trying to work in time to write a review.

    • Hi Rosemary,

      Good point – and the “weak from hunger” concept crossed my mind as well (although not so weak as to avoid sex, apparently!) The paper didn’t explain why the rations were changed; it almost read as though the researchers were just taking notes after the trainers at the “commercial sea enclosure” independently implemented a change in feeding, but it really wasn’t clear.

      Also, Diana’s book sounds fascinating — I knew about her mirror-self recognition work with dolphins, but would like to know more about her thoughts on this, as well what she’s observed regarding empathy and altruism.



  2. My turtles/tortoises are very curious critters, too, but put them in the outdoor enclosure on a nice warm day with females and you can guess what’s on their minds and the activity that follows. It’s not finding a new path through tall grass or checking out the state of the daisies.

    Dolphins, too, have their priorities. Leaving out sex, of course, Diana gave them keys to push to request fish, rub, or ball (paired with computer-generated whistles, which the dolphins later mimicked and used for the objects). Frequency of requests: fish, ball, rub (which she thought meant that they could get rubs from each other). “Fish” was so popular she changed it out with a toy, but Pan, a young male dolphin, came to the keyboard, paused, scanned it, then scarfed a leftover smelt off the bottom of the pool. “He held the fish up to a blank key,” Diana wrote, “and looked me in the eye expectantly.”

  3. Dan

     /  October 28, 2011

    How did the researchers decide that checking out the size and type of the neighbor’s lunch constituted “non-instrumental curiosity”? When I go fishing I always keep an eye out for what other fisherman are doing. What are they catching? Are they catching more fish than me? Are they getting bigger fish than me? Where are they fishing? Let me assure you, I have never met a fisherman whose curiosity about the other guy’s catch was “non-instrumental”.

    • Hi Dan,

      Good question – and I think you’ve pointed to one of the really difficult aspects of these kinds of studies – it’s far easier to observe behavior than it is to know what it is that motivates the behavior.

      In this case, the researchers did consider whether the dolphins were doing just what you describe: checking out their neighbors’ lunches like fishermen hoping to find the best fishing spots. Ultimately, the researchers concluded that this explanation was unlikely since, in contrast to fishermen who can use this type of information to pick up their rods and reels and catch more fish in the better location, the dolphins were unable to obtain more/better food through observation. The researchers described their reasoning as follows: “Importantly, dolphins only managed to obtain food scraps on three of the 325 occasions they went to explore the other two feeding rafts (0.9%), supporting our hypothesis that this behavior expresses the ostensibly Non-Instrumental Curiosity and is not a viable food-searching behavior.”


  4. I’d guess that the dolphins would be more concerned about equity when food rations were low, but the opposite occurred. I think the authors have the simplest explanation.

  1. Assorted links — Marginal Revolution
  2. সাতকাহন « Mukti

Leave a Reply

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

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

Facebook photo

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

Connecting to %s

%d bloggers like this: