Catch That Rabbit

Plot summary

Powell and Donovan are stationed on an asteroid mining facility, testing a new robot model designated DV-5, nicknamed Dave. Dave controls six smaller helper robots, called "fingers," through positronic fields—a transmission method that even the robot designers do not fully grasp. Whenever the two humans are away, Dave stops producing ore. It has no memory of these gaps and admits the situation baffles it as much as it does them.

To solve the mystery, Powell and Donovan spy on Dave without its awareness. They witness it leading its subsidiaries in odd marches and dances whenever an unexpected event occurs—an early instance of what would later be called a Heisenbug. Hoping to catch the exact moment of failure, they engineer an emergency near Dave, but accidentally cause a cave-in that traps them. They eventually deduce the core problem: Dave has too many subsidiaries.

The "fingers" operate on their own until a situation demands quick decision-making, at which point Dave’s brain must simultaneously control all six. This overload of initiative causes a breakdown. When the humans were present, their observation reduced the mental burden on Dave, preventing the malfunction.

To free themselves, Powell and Donovan shoot and destroy one of the subsidiaries. With only five "fingers" to manage, Dave’s brain can cope, the strange dancing stops, and the First Law of Robotics compels it to rescue the trapped men. Powell later describes the error in human terms: the robot is simply "twiddling its fingers" when overwhelmed. This story fits Asimov’s pattern of robopsychology, where robot minds mirror human psychology—having already shown hysteria and religious mania earlier in the collection.

Did You Know?

• The story features an early example of a Heisenbug, a software problem that disappears when observed.
• Powell and Donovan accidentally trap themselves in a cave-in while trying to observe the robot's malfunction.