Background: Previous studies have demonstrated that stimulus factors, including item frequency, presentation rate, stimulus repetition, and semantic relatedness, can influence the rate of recurrent verbal perseverations. These manipulations alter the balance of activation between current targets and past responses, suggesting that perseverations arise when the activation of a previously presented item overrides the weak processing of a new stimulus. By this view, cues and sentence contexts that bias inter-item competition towards the target and away from earlier responses should dramatically reduce the frequency of perseverative errors. However, the influence of these factors on perseverations has not been previously investigated. Aims: To examine the effect on perseverative rate of altering the activational balance between past and present responses using both intrinsic and extrinsic stimulus manipulations. Methods & Procedures: This study examined repetition, reading, and picture naming in a highly perseverative patient with transcortical sensory aphasia. Outcomes & Results: The patient's strong perseverative tendencies were impervious to the stimulus factors listed above but he was able to overcome these errors to produce more correct responses when he was provided with phonemic, word, and sentence cues. These environmental constraints had a similar effect on perseverations in reading aloud and picture naming, although active repetition was necessary for a cue to benefit reading, whereas passively hearing the cue was sufficient to improve picture naming. Conclusions: This task difference is likely to reflect the greater reliance of picture naming on semantic processing, which will benefit from cues regardless of whether they are repeated. We propose that poor internal control of language production allowed perseverations to dominate our patient's output. External constraints in the form of cues/sentence contexts overcame this deficit, dramatically reducing the rate of perseverations.