Several sturdy animal cages are installed on Hydra Island. After his capture by the Others, Sawyer was held in one cage at the Hydra facility, and Karl was held in a cage opposite Sawyer's. After Karl's escape, Kate replaced Karl. ("A Tale of Two Cities") After Sawyer and Kate's escape from Hydra Island, Jack was held in Sawyer's cage. ("Stranger in a Strange Land")
Sawyer's cage is essentially a Skinner box, a device that delivers positive reinforcements and punishments to the test subject in response to the subject's choice of voluntary behaviors, with the goal of shaping behavior through operant conditioning (B.F. Skinner, after whom the Skinner box is named, was specifically mentioned in the Swan Orientation film). The automated nature of the interactive controls and consequences enable the shaping of such behavior without the direct intervention of the experimenters. ("A Tale of Two Cities")
Inside Sawyer's cage was a food and water dispenser with a red button labeled with a knife-and-fork symbol. When the Sawyer pushed the button, a recorded voice said "Warning". A second push gave the same result, and before his third attempt, Karl warned Sawyer that he shouldn't press it again. Sawyer pushed it anyway and was thrown across the cage by an electric shock. ("A Tale of Two Cities")
There are two other controls in the cage: a foot pedal on the floor in a corner, and a paddle-shaped control near a top corner of the cage. Pressing all three at the same time dispenses a fish biscuit, some kibble, and a stream of drinking water from the food dispenser, and the tinny speaker attached to the dispenser plays a short clip of triumphant march music. The water flows through a pipe leading into a trough.
After some experimentation, Sawyer discovered how he could effect the reward by placing a rock on the foot pedal and simultaneously operating the paddle by throwing a boot at it and pushing the button by hand. Sawyer ate some of the fish biscuit and later threw the remainder to Kate in the adjacent cage. ("A Tale of Two Cities")
Tom mentioned that it only took "the bears" two hours to figure out the device. ("A Tale of Two Cities") (Sawyer replied, "How many of 'em were there?") In conversation with Juliet, Sawyer explicitly referred to the cages as being used to contain polar bears. ("Through the Looking Glass")
Sawyer later attempted to use the "punishment" function of the system to electrocute Ben Linus, but when Sawyer put his plan into action, he found, to his frustration, that the Others had disabled the system.
The cages and the nearby surrounding area are constantly being monitored by video surveillance. Ben overheard some of Sawyer's conversations and watched Kate's escape attempt; Jack later observed Sawyer holding a naked Kate on one of the monitors. There are also "subject escape" alarms that can be activated, presumably from the survelliance room, and blared over the loudspeakers. The cages are located near to the Hydra facility's walkway. ("Every Man for Himself")