Press the "Subject" button to start the experiment. You will see a stationary filled circle (the target) and a moving open circle (the bug). Try to move the bug to the target. You can do this by pressing the space bar to change the direction of the bug's movement. When the bug hits the target the computer will display the bug's path to the target and a measure of "efficiency" which is the distance the bug would have had to travel if it had moved directly to the target divided by the distance it actually traveled; the longer the distance actually travelled, the lower the efficiency.
Conventional psychology says that responses are selected by their consequences. This task shows that when you control you are selecting the consequences of your responses (bar presses).
The consequences that are supposed to be selecting responses are called reinforcements . A reinforcement is something (like money) that increases the probability of the response that produces it. In this study reinforcement is movement of the bug relative to the target: movement away from the target is strongest reinforcement because it results in the largest increase in the probability of the response (bar press) that produces it and movement toward the target is the weakest reinforcement because it results in no increase in the probability of the response that produced it.
In this task the reinforcing consequences of bar pressing are random: the consequence of any bar press is as likely to be a strong as a weak reinforcement. If your responses were selected by their consequences then your bar pressing would be random and the bug would wander around the screen hitting the target only by accident. The behavior of the bug that is being moved by responses that are selected by their consequences can be seen by pressing the "Reinforcement" button.
In fact, when you press the bar you are actually selecting the consequences (bug movements) that you prefer. You keep pressing the bar, changing the bug's movement, until the bug moves in the direction that you select. In this way you are able to select the ultimate consequence of your bar presses: bug on target. You press the bar to select the consequences (reinforcements) you want; reinforcements don't select the bar presses they want. The behavior of a bug that is being moved by responses (like yours) that are made to select consequences can be seen by pressing the "Control" button.
When you are able to press the bar to move the bug to the target, notice that you are pressing in order to get the bug moving toward the target. You press until the bug moves in a direction that you find to be satisfactory: you select the bug movement you want; the bug movement doesn't select your presses.
When the bug hits the target the computer prints the bugs path to the target. It also prints a measure of the efficiency of movement to the target. Efficiency is defined as the ratio of the distance that the bug would travel if it went straight to the target (the white line in the graphs of the bug's path to the target) over the distance the bug actually traveled. Perfect efficiency is 100%; this would only happen if, by chance, the bug started out moving directly to the target and keot moving in that direction.
When you are the subject, try to press the bar a quickly as possible when the bug is moving in the wrong direction. This is especially important at the start of the task in order to prevent the bug from running off the screen. If the bug does run off the screen just restart the task by pressing the "Subject" button.