"...antecedent stimuli that increase the probability of a desired response" (Piazza, & Roane, 2014, p. 256).

"...transfer stimulus control from therapist delivered prompts to stimuli in the natural environment that should evoke appropriate responses" (Walker, 2008 cited in Fisher, Piazza, & Roane, 2014, p. 412).

"...those in which some property of the criterion stimulus is altered, or other stimuli are added to or removed from the criterion stimulus" (Etzel & LeBlanc, 1979 cited in Fisher, Piazza, & Roane, 2014, p. 256).

"...addition of some behavior on the part of an instructor to evoke the desired learner behavior" (Fisher, Piazza, & Roane, 2014, p. 256).

"A sequence of responses in which each response produces a stimulus change that functions as conditioned reinforcement for that response and as a discriminative stimulus for the next response in the chain" (Cooper et al, 2007, p. 691).

"Reinforcement for the last response in a chain maintains the reinforcing effectiveness of the stimulus changes produced by all previous responses in the chain" (Cooper, Heron, & Heward, 2007, p. 691).