A pigeon is presented with a blue key and a red key alternatively. In the presence of the blue key, it earns food on a VI 30-sec schedule. In the presence of the red key, it earns food on a VI 15-sec schedule. The VI 30-sec schedule is then changed to a VI 60-sec schedule. As a result, the rate of response on the VI 15-sec schedule , illustrating a contrast effect.

As a result, the rate of response on the VI 15-sec schedule increases, illustrating a positive contrast effect.

Explanation:

A positive contrast effect is a type of behavioral contrast. A scenario is said to be positive contrast effect if the outcome is perceived to be better than its actual result. Actually it is compared with something worse.

In the above scenario, a pigeon is taken for test with a blue key and a red key alternatively. The pigeon is allowed to search for food with the keys alternatively. It earns food at different rate with different color keys. In this case, the rate of response on the schedule increases with the change in color of keys. This illustrates the positive contrast effect.

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