"...events, operations, and stimulus conditions with value-altering motivating effects that are unlearned" (Michael, as cited in Cooperet al, 2007, p. 377).

Surrogate CMOs replace and have the same effect as the motivating operation that it was previously paired with.

Reflexive CMOs create a circumstance in which its own removal serves as the reinforcement.

Transitive CMOs make other stimuli more effective reinforcers.

"A stimulus in the presence of which responses of some type have been reinforced and in the absence of which the same type of responses have occurred and not been reinforced; this history of differential reinforcement is the reason an SD increases the momentary frequency of the behavior" (Cooper et al, 2007, p. 694).

"An environmental variable that (a) alters (increases or decreases) the reinforcing or punishing effectiveness of some stimulus, object, or event; and (b) alters (increases or decreases) the current frequency of all behavior that has been reinforced or punished by that stimulus, object, or event" (Cooper et al., 2007, p. 699).

"...motivating variables that alter the reinforcing effectiveness of other stimuli, objects, or events, but only as a result of an organism's learning history..." (Cooper et al, 2007, p. 384)

"Any stimulus that systematically precedes the onset of painful stimulation becomes a CMO-R (reflexive- CMO), in that its occurrence will evoke any behavior that has been followed by such reinforcement" (Cooper et al., 2007, p. 385).

"When an environmental variable is related to the relation between another stimulus and some form of improvement, the presence of that variable functions as a transitive CMO, or CMO-T, to establish the second condition's reinforcing effectiveness and to evoke the behavior that has been followed by that reinforcer" (Cooper et al., 2007, p. 387).

Surrogate CMO's are stimuli that have been paired with another motivating operation and "acquired a form of behavioral effectiveness by being paired with a behaviorally effective stimulus" (Cooper et al., 2007, p. 384).