Motivating operations (MOs) may affect behavior in two ways; A) an MO momentarily alters the frequency of behavior for which a particular consequence has served as reinforcement (evocative-effect) and B) an MO momentarily alters the behavioral effects of the relevant consequence (value-altering effect). Many studies have empirically demonstrated the evocative function of MOs, however, few if any studies have attempted to systematically manipulate and measure the value-altering effect. The focus of this study was to investigate the value-altering effect by measuring choice and response allocation across two alternative tasks. Participants were two female girls diagnosed with autism. During conditioning sessions, experimenters created a history for the children in which clicking on a moving square on a computer monitor produced a small piece of edible. Prior to some conditions, the participants were allowed 5 min of free-access to the edibles, and in other sessions, access to edibles prior to session was restricted. During these sessions, the square was either red or blue depending on the condition type (pre-access or restricted-access). During probe sessions, both colored squares were concurrently available and participants were allowed to allocate their responding to whichever square they chose. One participant preferred the square associated with restricted-access, which may support the notion of the value-altering effect. Difficulties during conditioning sessions interfered with the ability to run sufficient probes with the other participant to evaluate a value-altering effect. Results suggest that the use of these procedures may be useful to differentiate evocative and function-altering effects of MOs.