Negative reinforcement the likelihood of a behavior being repeated, and punishment the likelihood of a behavior being repeated.

Negative reinforcement increases the likelihood.

Punishment decreases the likelihood.

Explanation:

In Operant Conditioning, reinforcements and punishments are mainly used. Both can be either positive (adding) or negative (removing).

A reinforcement tends to increase the likelihood of a behavior being repeated since, as the name states, it reinforces the individual's behavior; he/she will keep behaving a certain way in order for an aversive stimulus to be taken away. This is what we understand as negative reinforcement. A punishment decreases the likelihood of a behavior being repeated since the individual tends to avoid behaving a certain way in order to avoid being disciplined about it and receiving an aversive stimulus.