The aversion to saccharin persisted for over a month despite the fact that it was acquired after a single pairing of saccharin with radiation.Īn observation that immediately struck Garcia was that the rats seldom avoided the compartments in which radiation was delivered, and if they did, such avoidance took longer to establish and was less stable than taste aversion. As expected, when the irradiated rats were tested later, they strongly suppressed intake of the saccharin solution compared to a control group that had not been irradiated after consuming saccharin. Garcia tested this idea by giving rats a novel sweet-tasting saccharin solution during radiation exposure. Garcia and his colleagues speculated that the plastic containers may have given the water a novel taste that the rats associated with the subsequent sickness. The same rats would drink the water if it was provided in glass bottles. He noted that rats given water in plastic bottles prior to the induction of radiation sickness subsequently avoided drinking water from those bottles. Early in 1951, Garcia left graduate school at the University of California, Berkeley, and began working at the US Naval Radiological Defense Laboratory at Hunters Point in San Francisco, where he used the rat as a model to study the effects of exposure to radiation on living systems. In the 1950s, John Garcia demonstrated conditioned taste aversion under quite different laboratory conditions and came to realize that the phenomenon represented much more than a potential means of improving pest control. Julian Rzóska, one of the investigators in the research effort, surmised that the animals learned that the base food in which the poison was embedded made them sick and then they avoided the food on subsequent exposures.
This same strategy in the field would have the rats and mice avoiding foods associated with poison, but they would persist by living off other available foods.
After recovering from this toxicosis, the rodents stopped consuming the poisoned baits. This reluctance served to protect the rodents from death, but did not spare them from a rather intense poison-induced illness. In these studies, the rodents would often sample the baits but they would eat only small amounts. In an attempt to develop procedures for the eradication of rats and mice from foxholes and beachheads, Elton and his fellow researchers observed the consequences when rats and mice consumed poisoned baits. One of the first of these investigations was conducted in support of the British war effort by Charles Elton of the Bureau of Animal Population. Studies of what would later be termed conditioned taste aversions date back to at least the 1940s.
Our group and others are still exploring the implications of those findings today. Those results shook the foundations of psychology as it existed at the time, and led to a paradigm shift in thinking about how humans and other animals learn in general, and about the conditions under which learning occurs. What makes the connection between a novel taste and illness so strong that it can override these other types of experiences?Īnswers to these questions, as well as evidence for the reality of the phenomenon itself, were found not in anecdotes but in the results of experiments. Why are we so quick to place the blame for sickness on a novel-tasting food instead of blaming many other equally plausible possibilities? You may be thinking that blaming the unfamiliar food is the most logical response, but why does it seem that way? We’ve eaten new things many times before without becoming ill, and we’ve become ill before without eating anything new. No doubt many of us have had this type of experience.