Author information Copyright and License information Disclaimer 1This research was supported in part by Grant G from the National Science Foundation to Harvard University, and was carried out while the senior author was a National Institutes of Health predoctoral fellow. This article has been cited by other articles in PMC. Abstract The key pecking of two pigeons was reinforced on a variable-interval schedule of reinforcement during the presentation of each of two stimuli. In various phases of the experiment, punishment followed every response emitted in the presence of one of the stimuli.
The distension of the rectum and the disruption of the peristasis reinforce this effect. The foreign body may cause infections, destroying the intestinal wall. Depending on the location of the perforation, this may lead to a peritonitis due to the feces or an abscess in the retroperitoneal space. Smaller objects that injure the intestinal wall, but do not perforate it, may be encapsulated by a foreign body granuloma.