It was probably just as well that there were no animal rights activists picketing Dr. Howard Liddell's psychophysiology laboratory during his long career at Cornell University.
As it was, outside visitors might well have been appalled at what the man often referred to as "the father of American Psychopathology" was trying to accomplish with his research. Whether in his Cornell laboratory or at a research farm near Ithaca, New York (informally known as the "Behavior Farm" at Cornell), the experimental set-up was still the same. After attaching an electrical wire to one of the various research animals that he used (including pigs, sheep, and lambs), the animal was placed in a small chamber and received an electrical jolt immediately after a light flashed. The idea of the study was to teach the animal to associate the light with the electric shock. Since there was no way to avoid receiving the shock, the point of the research was to see how the animal responded to being in a situation where an aversive stimulus is unavoidable, essentially a learned helplessness scenario.
Dr. Liddell found that animals (usually sheep) receiving hundreds of unavoidable shocks tended to display an unusual set of symptoms. Along with twitching and jerking, the sheep often became rigid and stared at the floor. Even when returned to pasture, they behaved abnormally and avoided other sheep as much as possible. Inspired by the similar behaviour shown by humans with mental health issues, Dr. Liddell suggested that the shocked animal was displaying the equivalent of a human stress neurosis. The researcher coined the term experimental neurosis to describe how his shocked animals responded to unavoidable stress situations. He also attempted to reverse the neurosis by placing his traumatized sheep in the test chamber and flashing lights without a subsequent shock. Although the experimental neurosis could be completely reversed, it typically took numerous trials before the animal unlearned the fear responses.
There also seem to be significant differences between animal species with pigs being able to learn and unlearn fear responses much faster than sheep and goats. Dr. Liddell and his associates experimented with different stimuli (including metronome beats) and physiological effects of the experimental neurosis paradigm such as animal heart rate, respiration, and in the case of at least one dog, loss of sexual interest even when presented with a female dog in heat.
Who Was Howard Liddell?
Howard Liddell was born in 1895 and began his graduate work at the University of Michigan. He completed his training at Cornell University with joint interests in psychology and physiology. Inspired by a 1923 lecture at Cornell by one of Ivan Pavlov's former assistants, he developed what would be a lifelong interest in classical conditioning. That interest would be reinforced by two visits to Pavlov's Leningrad laboratory in 1926 and 1934. He was a major fan of Pavlov and even referred to him as "the psychiatrist of the future". Along with replicating Pavlov's experiments on a range of different species of animals, including dogs, sheep, goats and rabbits, Dr. Liddell also developed a fascination with the possible role that Pavlovian conditioning might play in mental illness.
By 1941, Dr. Liddell and his associates had completed numerous experimental studies on experimental neurosis, most of them carried out at the Ithaca research farm. Many of these studies dealt with lambs and kids and how they dealt with experimentally-induced stress, with or without the mother present and provided one of the first experiments on the role that mothers played in protecting their young from psychic stress. Along with his research, Dr. Liddell was also an active force for promoting the profession of psychology by serving on the editorial board of Psychosomatic Medicine as well as serving as president of the American Psychopathological Society and the Pavlovian Society of America (he was president-elect at the time of his death).
Although he impressed friends and colleagues with his genial manner and affable appearance, the publicity surrounding the Liddell experiments gave him an unfortunate reputation with the local press. According to one reporter describing one of Dr. Liddell's goat experiments in a 1950 article of Parade magazine:
When the shock comes, the animal jumps. Shocks, without advance warning, can go on indefinitely without giving him "nerves". But when the warning signal is introduced - that's when the trouble starts. At the sound of the bell, or the flashing of the light, he builds up tension or anxiety. When this kind of thing happens regularly he has a breakdown. Like the nervous clerk, who had been having anxieties and shocks in his job, the goat was stumped and confused, couldn't sleep nights. He became neurotic, shy, shunned other goats, became over-excitable.
However Dr. Liddell justified his research and the potential insights into why people became neurotic, it probably wasn't surprising that journalists nicknamed his Ithaca research facility as the "heebie jeebie farm". Many of the research animals there acquired their own nicknames and became stars in their own right (including Achilles the Neurotic Pig and Homer the Neurotic Goat). Despite local concerns about the fate of the various research animals on the farm, one Associated Press article describing the opening of the farm in 1937 stressed that the animals would "imitate man's artificial civilization to discover the cause and cure of nerves, psychoses and delinquency".
The Bikini Connection
As it happened, Dr. Liddell's research with psychoneurotic goats attracted military attention as well. Much of the early interest in experimental neurosis was inspired by the "combat fatigue" observed in soldiers during wartime. Liddell actually suggested that the experimental neuroses he produced in animals was equivalent to the "war neuroses" that soldiers huddling in foxholes or bomb shelters often faced. Military researchers were exploring the various medical and psychological effects that the newly-developed atomic bomb could have on soldiers facing nuclear explosions for the first time. Since they were reluctant to use actual soldiers in their atomic tests, Dr. Liddell's psychoneurotic goats seemed an acceptable substitute. In planning the ambitious Operations Crossroads nuclear tests carried out at Bikini Atoll in 1946, the Pentagon requested a number of the most neurotic goats that the Behavior Farm could provide to join the hundreds of test animals stationed on target ships (Liddell's goats were placed on board the USS Niagara anchored just two miles from the planned ground zero of the blast).
To record the reaction of the goats for posterity, researchers deployed a camera to watch as one of the goats reacted to being caught in the July 1, 1946 explosion. Although the USS Niagara actually sustained only minimal damage, the blast was later found to have killed ten per cent of all the animals on the test ships. Ironically, the neurotic goats were largely unaffected by the blast and researchers concluded that nuclear blasts weren't as traumatic as they had initially feared. Although medical officers later admitted that most of the animals involved in the test blast later died of radiation poisoning, the actual fate of Dr. Liddell's goats is still a mystery.
The Liddell Legacy
Dr. Howard Liddell died unexpectedly in 1963, just a few days after leading a section on animal behavior at the First International Symposium on Comparative Medicine. According to a tribute published in Psychosomatic Medicine by his friend and colleague James D. Block, "the personal force of Dr. Liddell was considerable. Impatient as he was of trifling obstacles, his presence in the laboratory swept everyone to fresher, stronger efforts. Of boundless energies, he nevertheless could spend hours of silent observation in the laboratory, the classroom, or the field- able immediately afterwards to extract and describe in extraordinary detail the most important facets of an animal's behavior".
Dr. Liddell's experimental neurosis research inspired a generation of researchers including cognitive behaviour therapy pioneers Joseph Wolpe, Arnold Lazarus, Eleanor Gibson, and Martin Seligman. Joseph Wolpe's early research was carried out following Howard Liddell's methods (although he used cats instead of goats). Based on his efforts to reverse the effects of experimental neurosis in animals, Wolpe first developed the method he termed "systematic desensitization" which has since become one of the standard therapy tools use by behaviour therapists to treat phobias and social anxiety. As for Martin Seligman, much of his early research with animals was carried out following Dr. Liddell's research methods and his theory of learned helplessness was heavily influenced by Liddell's work on experimental neurosis.
Would Howard Liddell's experimental neurosis research pass muster in a modern era of animal rights activism and ethical review boards? Probably not. Still, the value of Dr. Liddell's research as a way of understanding human psychopathology cannot be underestimated. What he accomplished with his research animals provides an important clue into why long-term stress can have a dramatic impact on human mental health and how it can be successfully treated.
All in all, an interesting legacy to leave for the future.