negative reinforcement
occurrence of a response produces the removal, termination, reduction or postponement of a stimulus which leads to an increase in the future occurrence of a response.
escape contingency
a response terminated an ongoing stimulus
avoidance contingency
a response prevents or postpones the presentation of a stimulus
free operant avoidance
avoidance BX is free to occur at any time and will delay presentation of a stimulus
discriminated avoidance
responding in the presence of a signal prevents the onset of a stimulus from which escape is a reinforcer.