Punishment is defined as a consequence that follows an operant response that decreases (or attempts to decrease) the likelihood of that response occurring in the future.
If you stroke a cat's fur in a manner that the cat finds unpleasant, the cat may attempt to bite you. Therefore, the presentation of the cat's bite will act as a positive punisher and decrease the likelihood that you will stroke the cat in that same manner in the future.
In an attempt to decrease the likelihood of a behavior occurring in the future, an operant response is followed by the removal of an appetitive stimulus. This is negative punishment.
When a child "talks back" to his/her mother, the child may lose the privilege of watching her favorite television program. Therefore, the loss of viewing privileges will act as a negative punisher and decrease the likelihood of the child talking back in the future.
A behavior (operant response) is sometimes less likely to occur in the future as a result of the consequences that follow that behavior. Events that decrease the likelihood of a behavior occurring in the future are called punishers.
A positive punisher is an aversive event whose presentation follows an operant response. The positive punisher decreases the likelihood of the behavior occurring again under the same circumstances.
Click here for an example of a positive punisher.
A negative punisher is an appetitive event whose removal follows an operant response. The negative punisher decreases the likelihood of that behavior occurring again under the same circumstances.
Click here for an example of a negative punisher.