• Background
  • Instructions
  • Stimulus Settings
  • Method Settings
  • Experiment
  • Results
  • Quiz

Background

On July 3, 1988, Iran Air Flight 655 was shot down by a U. S. missile from the navy vessel, the U.S.S. Vincennes. The missile killed all 290 passengers and crew, including 66 children. Though the United States has never apologized to Iran, the US government gave $61 million to the relatives of the victims of the attack. The incident took place at a time in which there was heavy tension between the United States and Iran, and Iranian jets had previously attacked US navy vessels. However, in this case, the radar on the Vincennes mistakenly judged the civilian airplane, an Airbus A300, to be an incoming Iranian F-14 fighter. Why had the U.S. Navy made such a terrible mistake?

Consider the radar specialist examining the screen that depicted incoming objects. He or she must decide based on the information available on the radar screen if the incoming object is an enemy warplane (Iran had F-14s) or a harmless jetliner (Airbus A300). How does one tell the difference? In a war-zone with an object approaching you at 600 miles per hour, decisions must be made quickly.

From the U.S. Navy’s standpoint, there are two types of errors that can be made. The Navy could mistake a civilian airplane for a military jet (as they did in this case), or they could mistake a military jet for a civilian airplane. Both of these errors could have fatal consequences for innocent people. In psychophysical terms, the navy’s actual error is called a false alarm, in which a harmless signal is perceived as dangerous. The other error is called a miss, in which a harmful signal is perceived as harmless. In one case, the danger is to innocent civilians aboard the aircraft, whereas in the other case, the danger is to equally innocent personnel aboard the US Navy ship.

In such a situation, there are also two potential correct responses. A correct rejection is when a harmless signal is perceived as harmless, and a “hit” occurs when a harmful signal is correctly perceived as dangerous. In this case, the correct response should have been a correct rejection.

In this experiment, you will play the role of the radar operator. You will look at a circular screen. You will see several dots. Most of these dots will be harmless civilian aircraft, but on some trials you will see one, flying faster (or moving faster across your screen). This faster dot is the target aircraft. You only have a brief period of time. After a few seconds, the screen will go blank, and you must make your decision.