Experiments were carried out on cats fitted with a gastric fistula. In one group of 6 cats basal gastric secretion, and in another group of 7 cats pentagastrin induced gastric secretion was collected two or three times a week during a 2 hr session. The sessions were conducted either in a "harness" situation where the cat's movements were restricted, or in a "cage" situation where the cat was unrestricted and could move freely. It was found that in four of 6 cats in the basal secretion group and in five of 7 cats in the pentagastrin induced secretion group, gastric acid output was significantly higher in sessions in harness than in sessions in cage. These differences in acid output were due to acidity rather than volume of secretion. It was hypothesized that restriction of the animal's movements in the harness could evoke a "reflex of freedom" which, however, could not be accomplished because of the confinement. This could evoke a neural conflict eventually leading to functional disturbances in the autonomic system. This, in turn, resulted in changes in gastric acid secretion.