10 of the most famous animals in Psychology

Psychologists have long studied chimps and other animals with two principal, related aims: to find out the capabilities of the animal mind, and to discover what makes us truly unique, if anything. This is a challenging field. As any pet owner knows, it's tempting to project a human interpretation onto animal behaviour. Researchers, especially when they've spent many years studying the same animal, can fall victim to this very bias (you'll see a theme of this field is the powerful, close bonds frequently formed between psychologist and animal). At the same time, though, there is also a temptation to overestimate our human uniqueness. Which emotions and capabilities are exclusively human? Tool use, perspective taking and deceit were once contenders, but no more, and the list is getting shorter all the time.

This Digest feature post is a celebration of the contribution that animals have made to psychology, including eight that we've come to know on first-name terms:

Hans the Horse

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The extent to which animals are truly capable of human-like intelligence has dogged psychologists for over a hundred years. A horse nicknamed Clever Hans (Der Kluge Hans in his native tongue) seemed to answer that question in dramatic fashion through his public performances in Berlin in early 1900s. Trained by a maths teacher Wilhelm Von Ofsten for four years, Hans appeared not only capable of simple arithmetic and telling the time, but by using hoof taps to correspond to letters, he performed even more astonishing feats, like identifying artists from their paintings or the composers of melodies. The German board of Education launched an 18-month long enquiry and found no evidence of fraud. However, the psychologist Oscar Pfungst eventually deduced that Hans must be reading tell-tale cues from whomever was questioning him because he could only answer correctly when his interrogator was visible.

This revelation highlighted some of the problems that have plagued animal psychology research ever since. Animals are highly receptive to human cues and many animal behaviours that seem impressive on the surface – and which seem to reveal complex animal cognition – may often have a simpler explanation (though Hans' ability to read cues, even when humans tried to conceal them, remains an incredible feat in itself). Unfortunately, the story ends sadly. Hans was recruited into the German war effort and, depending on which account you believe, was killed in action or eaten by hungry soldiers.

Pavlov's Dogs

I'm cheating a little with this (and the final) entry by including a group of famous animals rather than an individual, but it only seems right to mention the dogs studied by the Russian physiologist Ivan Pavlov given their contribution to psychology. The reason Pavlov's dogs feature in almost every introductory psychology class and textbook is because they revolutionised our understanding of learning, especially the principle of classical conditioning (detailed in a classic paper from 1927). Pavlov discovered classical conditioning almost by accident, when he noticed that his research dogs salivated when they heard cues that indicated to them that dinner was on the way. Pavlov soon found that he could get the dogs to salivate in response to almost any kind of previously meaningless cue, such as a bell, simply by pairing the bell repeatedly with the arrival of food. A challenge for later psychology research has often been to show that something more than basic learning processes, such as classical conditioning, are at play when animals perform apparently impressive feats of human-like intelligence.

See also 'The kingdom of dogs'

Washoe the Chimp

A long-running question in animal psychology has been whether human language can be taught to animals. Early in the last century, one idea was that our primate cousins might well be capable of human language if only they were raised in human culture. This prompted the wife and husband team of Luella and Winthrop Kellogg to raise the chimp Gua in their home alongside their son. It ended in failure of course, with Gua unable to speak. Decades later – it's strange it took so long – animal researchers realised non-human primates would never speak because of the anatomy of their mouth and vocal chords.

Recognition of this anatomical fact led to an intense period of several decades of work that attempted to teach apes sign language and, later, communication by symbols on a picture board. The first chimp to be taught sign language was Washoe (hence why I've chosen her for this list, rather than other famous research chimps including Kanzi and Nim Chimpsky). Washoe hailed from West Africa and was adopted by another spousal psychologist team, Allen and Beatrix Gardner. Washoe eventually learned to use over 250 different signs (her obituary in the New York Times in 2007 was headlined: Washoe, a Chimp of Many Words, Dies at 42). There is disagreement over whether Washoe ever really invented new words, such as the time she allegedly signed "water", "bird" at the sight of a swan. However, witnessing this apparent linguistic improvisation was according to at least one commentator (Harvard psychologist Roger Brown) "like getting an SOS from outer space".

Koko the Gorilla

Most of the ape language studies have involved chimps, but one particularly famous exception is Koko the Gorilla, who has been taught sign language (and exposed to spoken English) for decades by the psychologist Francine "Penny" Patterson. A few years ago Koko made headlines around the world when it was alleged by the Gorilla Foundation in California that she was mourning the passing of actor and comedian Robin Williams, who she'd met for an afternoon in 2001. A YouTube clip of their encounter (see above) has been viewed over three million times. Koko has also starred in her own books, including a children's book, Koko's Kitten, and been the subject of several film documentaries, most recently a BBC programme, Koko: The Gorilla Who Talks To People. "What we can really learn from this extraordinary science experiment turned love affair?" asks the film, highlighting in a nutshell one key problem with this entire field – the emotional closeness between researchers and the animals they study, challenging the pursuit of scientific objectivity.

The sad thing about the story of Koko and the other apes made famous by their part in psychological study is that the whole field has crashed, not only because of methodological criticism (most notably a devastating critique published in Science in 1979 by Herbert Terrace, leader of the Nim Chimpsky project, in which he argued that ape language is not human-like and doesn't feature real syntax), but also amid accusations of animal mistreatment. A recent Slate article summed up the situation: "No new studies have been launched in years, and the old ones are fizzling out. A behind-the-scenes look at what remains of this research today reveals a surprisingly dramatic world of lawsuits, mass resignations, and dysfunctional relationships between humans and apes." Similarly, a major new paper in Annual Reviews of Anthropology by Don Kulick says, "The threadbare field left today is an alarming not-so-funhouse of intrigue, betrayal, accusation, threats, litigation, dismissals, obese apes (unsurprising when most of their signing seems to be concerned with obtaining food rewards), dead apes, mass resignations, and even, inevitably, sex."

Peter the Dolphin

Sex is also a surprising theme of dolphin research that took place in the 1960s at a lab known as Dolphin House, built on the Caribbean island of Saint Thomas. There, John Lilley and his wife conducted investigations into whether dolphins are capable of mimicking human speech, and later into the effects of LSD on dolphins (to their surprise, the drug seemed to have no effect). As part of the language research, a woman called Margaret Howe Lovatt moved into a specially designed dolphinarium with a young male dolphin called Peter, living there more or less 24 hours a day in an office that overhang his water tank. The idea was that with constant human contact, it would perhaps be possible for a dolphin to fully grasp and imitate human language.

One problem: the pup's burgeoning sexual needs began to interrupt the language lessons. At first Peter was intermittently relocated to spend time with female dolphins in another tank, but Lovatt found that this interfered too much with her research and the bond she was trying to establish. So she began to satisfy Peter's needs herself. "It wasn't sexual on my part. Sensuous perhaps," she told Christopher Riley, the producer and director of the BBC documentary The Girl Who Talked To Dolphins. "It seemed to me that it made the bond closer," she continued. "Not because of the sexual activity, but because of the lack of having to keep breaking. And that's really all it was. I was there to get to know Peter. That was part of Peter."

This isn't just an odd tale, but a sad one. As Lovatt's experiment was coming to an end, news came that funding was being withdrawn from the lab (Riley says this is because of wider concerns about the welfare of all the resident dolphins). The following year, Dolphin House lab was forced to close. The story goes that after being moved to claustrophobic surroundings in Miami, Peter took his own life.

Alex the Parrot

Language skills and a keen intelligence are not only the preserve of apes and dolphins, as shown – to many experts' surprise at the time – by the remarkable achievements of the African Grey parrot Alex (an acronym for "Avian Learning Experiment"), who was studied for 30 years by the psychologist Irene Pepperberg, until the parrot's death in 2007 at the age of 31.

Pepperberg, who bought Alex from a pet store in 1977, was apparently inspired to study Alex because she'd read about the linguistic achievements of Washoe (see above) and other animals. As well as being famous for his one liners, Alex apparently learned over 100 words, could name over 50 objects and knew his colours and shapes. He starred in several BBC and PBS documentaries. Like many of his ape peers in the research world, Alex also received notable obituaries upon his death. The Economist referred to him as science's "best known parrot". The New York Times ran with "Brainy Parrot Dies, Emotive To The End", in reference to the fact that Alex's last words to Pepperberg the night he died were "You be good, see you tomorrow. I love you."

Compared with his ape peers, it seems that Alex contributed to research that is more likely to stand the test of time. He featured in dozens of quality peer-reviewed papers by Pepperberg (by contrast, it's over 20 years since the on-going Koko project published a significant language paper in a peer-reviewed journal, and that was in the Russian Journal of Foreign Psychology). In his recent review of human-animal communication, anthropologist Don Kulick wrote the "… emphasis on cognition and downplaying of language seem to have protected Pepperberg's studies [of Alex] from the sort of critical onslaught that pulverized ape-language research".

Betty the Crow

Alex is far from being the only smart bird in town. Betty, the New Caledonian crow, though less famous than the parrot, made headlines around the world in 2002 when it was reported that she had shown the ingenuity to make a hook out of a straight piece of wire, to reach food in a plastic tube (another crow had taken off with the hook provided by the researchers). This was considered a big deal because, as one of the researchers told the BBC, "Although many animals use tools, purposeful modification of objects to solve new problems, without training or prior experience, is virtually unknown". In fact, the researchers claimed Betty's tool-making was more impressive than the tool use seen among chimps.

However, as is usually the way with animal research of this kind, doubts have since been raised about the way Betty's feat was interpreted. Last year, a different team of researchers studied 18 New Caledonian crows as they made tools with the branches they use in the wild. Crucially, the researchers observed that most of the birds performed the same final modification – to create a hook shape – as seen by Betty in the lab. In other words, Betty's feat was not entirely spontaneous, but probably part of her species' natural repertoire. Meanwhile, while we're talking about corvids, an honourable mention should go to psychologist Nicky Clayton's scrub-jays, who have been observed demonstrating many behaviours previously considered uniquely human, such as advanced deceit. For instance, a jay will re-hide her food stash if a potential thief was nearby when she first hid it.

Chaser the Border Collie

Not to be outdone by the birds and the apes, a dog named Chaser the Border Collie can reportedly recognise over 1000 words, having been trained extensively through play by the psychologists Alliston Reid and John Pilley. "We have found that play is infinitely greater than food [for training]. It's not as distracting and dogs don't satiate on play" says Pilley in a promotional video (see above) for his New York Times best-selling book, Chaser: Unlocking the Genius of The God Who Knows a Thousand Words. Are Chaser's skills an example of true animal intelligence? Pilley thinks so: "These kind of findings definitely show that lower animals, especially dogs, are not machines with blood. They have emotions, they have mental processes." But again, anyone watching Pilley with his research subject will see the common problem of an emotional bond between scientist and animal, potentially blurring objectivity and making it difficult to interpret research findings. That said, in the formal published paper detailing Chaser's achievements, Pilley claims to have ruled out the possibility that Chaser relies on visual cues, "Clever Hans style".  Chaser's fame continues to grow through regular documentary appearances, including on 60 Minutes and National Geographic and on the BBC.

Echo the Elephant

Echo the elephant died in 2009 at the age of 64 having been filmed and observed in Kenya's Amboseli National Park for several decades, making her the world's most studied elephant (although, strictly speaking she was the subject of ethological rather than psychological study). Echo, who was her tribe's matriarch for about 36 years, starred in at least four documentaries, including David Attenborough's Echo: An Unforgettable Elephant. The principal researcher was ethologist Cynthia Moss who, like many of the other researchers mentioned in this list, formed a powerful emotional bond with Echo. Moss learned from Echo and the other elephants of Amboseli about their emotional lives, their transmission of cultural practices and their capacity for future planning and teamwork. This is illustrated in the clip above, in which Echo marshals the support of her tribe's adult females to execute an apparently daring rescue of her daughter, Ebony, who had been kidnapped by a rival tribe.

Harlow's Monkeys

I'm going to cheat again for this last entry and rather than name a specific creature, include a group of animals who helped us better understand a fundamental fact about ourselves.

The importance of physical touch between mother and baby is today widely recognised, but back in the 1950s this wasn't the case, thanks in part to the influence of Freud and his ideas that an infant bonds with her mother primarily because she satisfies her basic needs of thirst and hunger. The American psychologist Harry Harlow's research in the 1950s with rhesus monkeys changed this. Though ethically controversial, it provided a powerful demonstration of the importance of physical contact in mother-infant attachment.

Inspired by his observation that monkeys separated from their mothers grew highly attached to and possessive of their blankets, Harlow created two forms of surrogate mother: one made of wire that provided milk, another warm and soft that provided comfort but no milk. Given the choice, infant monkeys spent the majority of their time with the soft, warm version. However, without their mothers, even the monkeys who clinged to the cloth-covered surrogates developed serious behavioural problems later, lending graphic evidence to support the British psychologist John Bowlby's claims about the importance of early maternal care.

Which animals would you have included on this list and why? Answers via comments or tweet us @ResearchDigest #famouspsychologyanimals