Tests Show Radiation Causes Abnormal Fear

Grad Student's Experiments Prove Unusual Panic Follows Exposure

In the event of atomic war, what would be the reaction of irradiated combat personnel?

From the work of Ogden R. Lindsley, student at the Graduate School of Arts and Sciences, has come the first partial answer to this question. The answer also represents the first stop towards a new, behavioral test for radiation sickness.

In experiments on dogs, Lindsley has found that two hours after radiation the animals exhibit marked anxiety and fear, and are often unable to perform their accustomed tasks.

If the situation is the same for humans as present evidence indicates a soldier irradiated from the blast of an atom bomb or artillery shall, or contaminated by the radioactive dust scattered by the blast, would panic or "freeze" in a fearful battle-ground situation.

He would appear physiologically normal in all respects. His perception would remained unchanged. But he would be able to defend himself poorly, if at all.

Lindsley's findings are not all gloomy, however. The same fear that can be disastrous on the battlefield can also give the first indication of radiation sickness, days in advance of chemical tests and clinical symptoms.


With prompt identification and immediate treatment, the way may be open to the saving of thousands of lives.

Lindsley, who is a student in the Department of Experimental Psychology, carried on his experiments at the Atomic Energy Commission laboratories, directed by Dr. W. W. Jetter of the Boston University Medical School. His basic tool in these experiments was a device known as the "Skinner Box." This is a small, cubby-hole sort of enclosure, in which the dog is placed. Inside the box are a feeding trough, a metal lever, and several electrical appliances, such as lights, buzzers, and horns that can be regulated from the outside. When the box is closed, it provides a perfectly controlled environment, by which the experimenter can test a particular segment of the dog's behavior.

Lindsley's method in these experiments was an adaptation of the technique developed by B. F. Skinner, professor of Psychology, and inventor of the "Box" which bears his name. Through the study of pigeons and rats, Skinner and other experimental psychologists, have discovered means for controlling an animal's behavior, and certain laws to which that behavior conforms. It was found that an animal, who has to perform a certain task for his food will work at a highly constant pace, when he is rewarded with food at an arbitrary, erratic rate.

Skinner Box

Lindsley placed his dogs in the Skinner Box, and taught them to press the lever in order to get food. He rewarded them intermittently, however. A dog would sometimes obtain food for one or two lever presses; other times, it would take a few hundred to do the trick.

By such a procedure, Lindsley got his dogs to work at a constant rate, each pressing the lever an average of over 3,000 times an hour. The next step was to break up the hour a day during which each dog worked into parts where the dog would sometimes not get paid off, no matter how much pressing he did on the lever. For the first 15 minutes, everything continued as before--the dog worked at a constant rate, and was rewarded at erratic intervals. Then came 10 minutes where the animal would not get paid off at all. During these 10 minutes, a light in the box flashed. All the dogs eventually learned that the light was a signal that work would go unrewarded. Thus, the dogs immediately ceased pressing the lever when the light went on. Next came another 15-minute period of constant response from the dog, provoked by the arbitrary reward schedule. Following this was five minutes during which a buzzer sounded. The dogs would be fed as before if they continued to work. The dogs were not initially frightened by the buzzer, and worked while it operated. Later during the last five seconds of the buzzing, however, an extremely loud horn was turned on. Not one dog worked during the horn, even though they could get food by pressing the lever while the horn was blaring. The sounding of the horn was a fear stimulus to the dogs.

In subsequent work periods, the majority of the dogs did not work during the buzzer, which, by association with the horn, had become a learned fear stimulus.

Stabilized Behavior

By such a procedure, Lindsley had produced highly stabilized and regular behavior in the dogs, and had conditioned the animals' behavior to certain factors--when the light was on, the dogs would remain idle, when the buzzer sounded, the animals refused to work. With such stability and consistent performance, any changes in the dogs' behavior due to radiation could be observed.

One hour after irradiation, the dogs were placed in the Skinner Box for their usual hour work-period. The canines discriminated the light as before, remaining idue during the 10 minutes it was on. What followed next, though, was singular and unexpected. Not only would the animals refuse to work during the buzzer's blaring, but either stopped work before the buzzer sounded, or did not go to work after it stopped.

Heightened Fear

This shows a heightening of the fear response, both during and beyond the presence of the fear stimulus. In human terms, this would mean that irradiated soldiers would show fear not only during an air raid, for example, but also after the danger had passed.

Of those that continued to work through the buzzer as before, each dog manifested fear in some form. Their hair bristled, their tails went between their legs, or they worked at a decreased rate.

Five days after this first fear reaction, which had never been observed before, came a second stage similar to the first, this time lasting a day or two. Only once before this stage had been observed. It was not until the final, clinical stage, occurring 10 to 15 days after irradiation, that the traditional signs of the illness were evident. In this stage, the animals developed fever, the white corpuscle count went down, they lost appetite and weight.

On the heels of the clinical stage, came death to 30% of the irradiated dogs.

Effect on Soldiers

It is the first stage that interests Lindsley, as psychologist, because of its obvious strategic importance with respect to increased anxiety and fear of combat personnel following even sub-lethal doses of radiation. "The results obtained from these experiments with dogs are based on laws of animal behavior learned through the study of pigeons," says Lindsley. "Most probably a human's reaction to irradiation would be the same as a dog's--for it's a bigger phylogenetic jump from the pigeon to the dog than from the dog to man." Also significant is the fact that many people irradiated in the treatment of cancer have reported nervousness and anxiety in the two-hour period following treatment.

The next step that must be taken, according to Lindsley, is the development of medicine that will counteract the fear following irradiation. Just as important, is the establishment of a predictive correlation between the severity of the anxiety in the first stage, and the severity of the clinical stage. Such a development would afford a means for quick and efficient diagnosis of radiation sickness, and would clear the way for its prompt treatment.

Lindsley notes that his experiments are not classified, in keeping with the Atomic Energy Commission's determination to allow free circulation of results which might benefit humanity. Lindsley hopes his experiments will contribute to that end.