Stimulus over-selectivity refers to the phenomenon whereby behavior is controlled by a subset of elements in the environment at the expense of other equally salient aspects of the environment. The experiments explored whether this cue interference effect was reduced following a surprising downward shift in reinforcer value. Experiment 1 revealed that a downward shift in reinforcer value reduced over-selectivity in non-clinical adults under-taking a concurrent cognitive task. Experiments 2 and 3 ruled out a generalization decrement account of this effect; through manipulating the color of the stimuli across phases, we failed to find a reduction in over-selectivity, except for when the nature of the stimuli in one task changed in the context of another one that remained the same. Experiment 4 explored whether a reduction in over-selectivity is a function of the reinforcer and not the stimuli and failed to find a differential effect of reinforcer quality. Taken together, the results extend earlier findings of an attenuation of blocking following a surprise downward shift in reinforcer value to an over-selectivity paradigm in human subjects. Such work has important implications for remediation of over-selectivity. (Contains 2 tables and 6 figures.)