Which of the following is a factor that can decrease responses over time?

A punisher is a factor that can lead to a decrease in responses over time because it introduces an unpleasant consequence following a behavior, making it less likely for that behavior to be repeated. When an individual experiences a punisher after engaging in a specific action, it serves as a deterrent, thereby reducing the frequency of that action in the future. This principle is central to operant conditioning, where the outcomes of a behavior influence its occurrence.

In contrast, positive reinforcers tend to increase the likelihood of a behavior being repeated by providing a rewarding outcome. A neutral stimulus typically does not affect behavior directly, as it does not carry any inherent positive or negative consequences. Response cost, which involves removing a reinforcing stimulus as a consequence of a specific behavior, can also lead to a decrease in that behavior. However, it is important to note that a punisher is specifically designed to reduce behaviors by introducing a negative consequence, while response cost focuses on the removal of positive factors.