During the experiment, the researchers offered both groups of rats access to morphine-spiked water, which was sweetened enough to overcome the bitter taste that would normally make rats avoid such a beverage. They also had access to plain water. But while the caged rats lapped up the morphine draught, the Rat Park residents mainly refused. Under some conditions, the caged rats took 19 times more morphine than the rats that had companions and space to explore. Even when all of the rats were made physically dependent on morphine and taught that drinking it could relieve withdrawal symptoms, the
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