What does it take to know that we think? , asks S.Ananthanarayanan.
The methods of Artificial Intelligence have created a mechanised view of the process of thought, but there are features that mark AI as clearly ‘artificial’. One of the questions raised is, even if we consider that a computer is thinking, can we say the computer knows it is thinking? And extending the question, are animals aware of thought, like humans are?
Katherine McAuliffe, Lindsey A. Drayton, Amanda Royka, Mélisande Aellen, Laurie R. Santos and Redouan Bshary, at Boston College, Massachusetts, Yale University and the University of Neuchâtel, Switzerland, describe in the journal, Nature Communications Biology, a study of a species of fish that fashions its actions based on what her partner may be thinking. Such ability has been considered restricted to humans and some human-like primates. “Much of human experience is informed by our ability to attribute mental states to others,” says the paper. The capacity has been seen in primates, mainly, but could there be situations where something akin appears in other kinds of animals?
The paper says most studies in non-human primates are with the help of competitive, food seeking situations. The paper cites a previous study where rhesus monkeys consider whether a competitor can or cannot see them when trying to steal food – they reach for the food more readily if the face of the competitor is covered, compared to when the competitor’s body alone is hidden. Similarly, with chimpanzees in a dominant-subordinate relationship, the subordinate animal prefers to take food that is hidden behind a barrier, over food that is in front of the barrier. “Non-human primates can also track what a competitor has seen in the recent past and can strategically conceal visual and auditory information in an attempt to deceive their rivals,” says the paper. And, that while the mechanisms are not understood, it looks like the animals share with humans the ability to form an image of what others see and know.
The evidence collected so far is of primates, and some animals with comparable brain-size-to-body ratio, like corvids. But, is it the large brain that helps this behaviour arise? Could there be circumstances which enable the capacity to evolve in other species? The authors find that the answer is in the affirmative – they describe the behaviour of a small fish, the blue streak cleaner wrasse, just 10-14 cms long, found in many coral reefs, which appears to take into account what her male partner could be thinking, while planning her own strategy in a highly characteristic form of behaviour.
The cleaner wrasse is so called because the fish feed on parasites and dead tissue on the bodies and in the mouth and gills of larger fish, in a kind of symbiotic relationship. The larger fish get the service of being cleaned, while the smaller ones find food, and protection. While finding food in this way, however, wrasse, which often work in pairs, also take a nibble at the living tissue of the client fish, or a bit of mucus. When this happens, the client fish considers the bargain violated and swims away.
Over a decade ago, co-author, Redouan Bshary and others at Neuchâtel had studied the co-operative behaviour of pairs of wrasse, in their foraging. In further study, now published, the authors discover features that show that wrasse must think, and be aware of what their partners know, while they regulate the way they feed.
As we have said, the wrasse, sooner or later, take a bite of living tissue, and this is the end of the feeding session. But, how long do the fish restrain themselves? It had been noted that this was like picking apples in an orchard. One way is to take a few apples from each tree and move on to the next. This has the advantage of getting the lowest hanging fruit, but has the cost of having to move frequently to the next tree. On the other hand, if we picked more fruit from the same tree, we would save the need to move, but we would need to reach higher after the first few fruit. The best way would be somewhere in between. Wrasse, too, find it progressively more difficult to find flakes as they start feeding. And at some stage, taking a bite of living tissue is worth the loss of the feeding station.
Things become a little different when a pair of wrasse are cleaning a client fish. The moment one of the pair takes a bite of living tissue, the feeding stops for both. There is hence an incentive for each of the wrasse to be the first to take that bite. Except that, if one fish kept being the first one, the partner would feel deprived of feeding, with no pleasure of living tissue, and may decide to terminate the union. This, it was found, led to pairs of wrasse staying on for longer than when there was only a single wrasse, and it was found that the female was more often the one that showed greater patience.
The current study has gone one further. It finds that when the female of the pair goes first for the forbidden nip, the male does not just feel resentful and think of breaking the partnership. Being the larger built of the couple, the male pursues the female and gives her a bite, as punishment. This behaviour may be what drives the female to forebear, and the reason that the female is less frequently the partner who causes the client to depart.
But what does this have to do with knowing what one’s partner is thinking? Well, the female knows that she is in for it if she is caught taking an early bite of living tissue. The authors of the paper arranged for screens to be placed so that the female got an opportunity for a go at a model of the client either in view of her partner or when she was concealed. And the result of trials was it when the male saw the female biting the client that he went after her to chastise her. But if the client left and the male cleaner had seen nothing, well, he was not likely to think the female needed instruction.
The trials also revealed that the female was more inclined to nick the client when she was hidden, than when in sight. And further, that the behaviour was more pronounced when the male was one who believed in more severe punishment. Arrangements were also made to keep the male in sight of the female or concealed. And it was seen that she displayed more vigorous cleaning of dead tissue when the male was watching! And even that she sought to be visible when she was cleaning dead tissue, to show that her behaviour was co-operative, as opposed to competitive.
The study hence shows that the blue streak cleaner wrasse is sensitive to what her partner may be thinking, and then acts deceptively, to condition his thinking. And more significant, that a species like fish, which is genetically far removed from humans, as opposed to primates, who are closely related to humans, can display this ability!
------------------------------------------------------------------------------------------ Do respond to : response@simplescience.in------------------------------------------- 