In preview search a new target is difficult to detect if it carries a feature shared with the old distractors [Braithwaite, J. J., Humphreys, G. W., & Hodsoll, J. (2003). Color grouping in space and time: Evidence from negative color-based carry-over effects in preview search. Journal of Experimental Psychology: Human Perception and Performance, 29(4), 758–778.] Two experiments are presented which examined whether this negative color carry-over effect is dependent on an attentional-set to ignore old, irrelevant distractors. Consistent with this, the data show that the negative carry-over effect is greatly reduced if the attentional-set to ignore the old preview items is removed and replaced by a set to prioritize the old items instead. The findings demonstrate that preview search, and the carry-over effect, are at least partly determined by a top-down intentional bias against old, irrelevant information.