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Monday, August 22, 2011

Animal cognition: Chimps fake laugh, sheep know taxonomy and pigeons better at stats then us

(thanks to Damien C for the link!)

Think You’re Smarter Than Animals? Maybe Not

Alexandra Horowitz is the author of “Inside of a Dog: What Dogs See, Smell and Know.” Ammon Shea is the author of “The Phone Book: The Curious History of the Book That Everyone Uses But No One Reads.”

HUMANS have long been fascinated with animal intelligence. Scientific studies have asked if animals use language or tools; have culture; can imitate, cooperate, empathize or deceive.

Inevitably, the results of these studies invite comparison with our own cognitive faculties. In such comparisons, humans nearly always come out on top. An impartial observer might suggest that the deck is stacked. After all, we are the ones running these tests.

But if we look at some of the subtler aspects of animal behavior, the beasts begin to offer surprisingly stiff competition. A few recent research papers describe animal competence at social and cognitive tasks that humans often struggle with — mastering conversational etiquette, understanding botanical classification, competing on game shows and figuring out how to get a drink when you’re thirsty and the only glass of water is glued to the table and your hands are tied behind your back.

“Aping Expressions? Chimpanzees Produce Distinct Laugh Types When Responding to Laughter of Others,” in the journal Emotion (2011).

You’re at a dinner party. Your hostess regales you with a long, meandering tale of her recent back surgery. It ends with attempted humor: she laughs and glances at you. You laugh in response, trying to convey an appreciation for her humor that you don’t actually feel. Congratulations: you are now at the level of social politeness of chimpanzees.

In this study, the laughs of 59 chimps (yes, they do laugh) were recorded and the sounds analyzed. The researchers discovered that when one chimp laughed others sometimes engaged in “laugh replications” that lacked the full acoustic structure of spontaneous laughter. In other words, they were fake-laughing.

This happened more often in more newly formed colonies, where, perhaps, the individuals were less familiar with one another. With your spouse of 25 years, you can simply stare at him stony-faced when he tells you his favorite “funny” story yet again.

“Do sheep (Ovis aries) categorize plant species according to botanical family?” in Animal Cognition (2011).

Type “Is the tom...” into Google, and the search engine, presuming that you are beset with the same burning question that has plagued so many, offers to finish your query for you: “Is the tomato a fruit or a vegetable?” Given that we humans are still puzzled by the botanical status of one of our most common vegetables, er, fruits, the performance of the 12 lambs described in this study is humbling.

After learning that eating sainfoin, but not fescue, was followed by a stomachache, the lambs knew to pick cocksfoot over alfalfa when given the choice in the future. Have no idea what this means? In non-lamb terms, if a pasture legume caused indigestion (thanks to lithium chloride added by the researchers) but a grass found in pastures did not, the lambs, when facing a later choice between a different legume and a different grass, opted for the grass over the legume. In other words, the lambs demonstrated an ability to form a generalization about the relative digestibility of families of plants. (Lest sheep let these findings go to their heads, note that recent research found that some plants communicate with each other to raise defenses against herbivores.)

“Are Birds Smarter Than Mathematicians? Pigeons (Columba livia) Perform Optimally on a Version of the Monty Hall Dilemma,” in the Journal of Comparative Psychology (2010).

The old game show “Let’s Make a Deal” inspired a famous probability puzzle. A contestant has three doors to choose from: one hides a spectacular prize; the other two each hide something considered undesirable, like a goat. Once the contestant makes a choice, the host, Monty Hall, reveals a goat behind one of the unchosen doors, and offers the contestant the chance to switch his choice to the third door.

On the show, few people switched. But famously, probability shows that it is much better to switch. We humans are reluctant to accept this: in laboratory studies, subjects switch only a third of the time. We perform only slightly better if we get a chance to play the game dozens of times or if the probability is explained to us beforehand.

But pigeons that were offered a version of Monty Hall’s choice aced the test. The experiment involved pecking keys and winning “mixed grain,” instead of selecting doors hiding unknown prizes. After training in the game, the pigeons switched 96 percent of the time. The lesson? Take a pigeon with you if you’re going to be on this game show (now back on television).

“Rooks Use Stones to Raise the Water Level to Reach a Floating Worm,” in Current Biology (2009).

One of Aesop’s fables tells the tale of a crow who quenches his thirst by filling a nearly empty pitcher with stones until the water level rises high enough to drink. Displacement is an insightful solution — could a bird really come up with it? After all, one can easily imagine humans failing to do so (say, reality-show contestants who, faced with an immobile glass and a “no hands” rule, contort themselves futilely).

In this study, four rooks (a type of bird) faced an Aesopian task: confronted with a vial partly filled with water and holding a floating worm, could they extract this bounty?

Easy. After considering the problem, they collected and dropped into the tube just enough stones to bring the worm within snatching distance. Look for this challenge to be included in the next season of “Fear Factor.”

There is no need to be either frightened or overly excited by these findings. The animals won’t be taking over anytime soon, and there is very little chance you can train your parrot to help your child get into the right kindergarten (even animal cognition has its limits). And there is still one notable area of behavior in which animals have shown no sign of matching us: they appear to be not at all interested in running experiments testing our cognition.

Smart animals.


Davila-Ross M, Allcock B, Thomas C, Bard KA (2011) Aping Expressions? Chimpanzees Produce Distinct Laugh Types When Responding to Laughter of Others. Emotion DOI: 10.1037/a0022594

Humans have the ability to replicate the emotional expressions of others even when they undergo different emotions. Such distinct responses of expressions, especially positive expressions, play a central role in everyday social communication of humans and may give the responding individuals important advantages in cooperation and communication. The present work examined laughter in chimpanzees to test whether nonhuman primates also use their expressions in such distinct ways. The approach was first to examine the form and occurrence of laugh replications (laughter after the laughter of others) and spontaneous laughter of chimpanzees during social play and then to test whether their laugh replications represented laugh-elicited laugh responses (laughter triggered by the laughter of others) by using a quantitative method designed to measure responses in natural social settings. The results of this study indicated that chimpanzees produce laugh-elicited laughter that is distinct in form and occurrence from their spontaneous laughter. These findings provide the first empirical evidence that nonhuman primates have the ability to replicate the expressions of others by producing expressions that differ in their underlying emotions and social implications. The data further showed that the laugh-elicited laugh responses of the subjects were closely linked to play maintenance, suggesting that chimpanzees might gain important cooperative and communicative advantages by responding with laughter to the laughter of their social partners. Notably, some chimpanzee groups of this study responded more with laughter than others, an outcome that provides empirical support of a socialization of expressions in great apes similar to that of humans.

Ginane C, Dumont B (2011) Do sheep (Ovis aries) categorize plant species according to botanical family? ANIMAL COGNITION 14(3): 369-376, DOI: 10.1007/s10071-010-0371-4

The ability of grazing herbivores to assign food types to categories by relying on certain relevant criteria could considerably reduce cognitive demand and increase their foraging efficiency when selecting among many different plant items. Grasses and legumes differ functionally in vegetation communities as well as in nutritive value. We aimed to determine whether sheep can generalize an aversion they learnt for a grass or a legume species to another species of the same functional type and consequently whether botanical family is a potential level of categorization. Over four successive weeks, 12 lambs were conditioned against either a freshly cut grass (tall fescue—Festuca arundinacea, N = 6) or legume species (sainfoin—Onobrychis viciifolia, N = 6) using a negative post-ingestive stimulus (lithium chloride) on day 1. Preference of all lambs between another grass (cocksfoot—Dactylis glomerata) and another legume (alfalfa—Medicago sativa) was assessed on day 3 by measuring their relative consumptions. Preference for alfalfa progressively became lower for lambs that were conditioned against sainfoin than against tall fescue, indicating that lambs generalized the aversion between species along some perceptual gradient and classed the considered grasses and legumes in distinct categories. Beyond this original result, the question now is to identify which specific plant characteristics or functional traits the animals rely on in order to form categories.

Herbranson WT, Schroeder J (2010) Are birds smarter than mathematicians? Pigeons (Columba livia) perform optimally on a version of the Monty Hall Dilemma. Journal of Comparative Psychology, 124(1): 1-13. doi: 10.1037/a0017703

The “Monty Hall Dilemma” (MHD) is a well known probability puzzle in which a player tries to guess which of three doors conceals a desirable prize. After an initial choice is made, one of the remaining doors is opened, revealing no prize. The player is then given the option of staying with their initial guess or switching to the other unopened door. Most people opt to stay with their initial guess, despite the fact that switching doubles the probability of winning. A series of experiments investigated whether pigeons (Columba livia), like most humans, would fail to maximize their expected winnings in a version of the MHD. Birds completed multiple trials of a standard MHD, with the three response keys in an operant chamber serving as the three doors and access to mixed grain as the prize. Across experiments, the probability of gaining reinforcement for switching and staying was manipulated, and birds adjusted their probability of switching and staying to approximate the optimal strategy. Replication of the procedure with human participants showed that humans failed to adopt optimal strategies, even with extensive training

Bird CD and Emery NJ (2009) Rooks Use Stones to Raise the Water Level to Reach a Floating Worm. Current Biology 19(16): 1410-1414 doi:10.1016/j.cub.2009.07.033

In Aesop's fable “The Crow and the Pitcher,” a thirsty crow uses stones to raise the level of water in a pitcher and quench its thirst. A number of corvids have been found to use tools in the wild [1,2,3,4], and New Caledonian crows appear to understand the functional properties of tools and solve complex physical problems via causal and analogical reasoning [5,6,7,8,9,10,11]. The rook, another member of the corvid family that does not appear to use tools in the wild, also appears able to solve non-tool-related problems via similar reasoning [12]. Here, we present evidence that captive rooks are also able to solve a complex problem by using tools. We presented four captive rooks with a problem analogous to Aesop's fable: raising the level of water so that a floating worm moved into reach. All four subjects solved the problem with an appreciation of precisely how many stones were needed. Three subjects also rapidly learned to use large stones over small ones, and that sawdust cannot be manipulated in the same manner as water. This behavior demonstrates a flexible ability to use tools, a finding with implications for the evolution of tool use and cognition in animals.

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