Stimulus-specific information stored in visual working memory (VWM) is systematically biased by subsequent visual inputs, particularly when those inputs physically resemble the remembered information. Although these memory biases have traditionally been attributed to passive interference triggered by physical feature overlap, recent work suggests that explicitly comparing VWM contents to new perceptual inputs may actively modulate the magnitude of these biases. Here, we tested this modulation hypothesis by examining whether VWM representations are more strongly biased by a novel perceptual input when observers explicitly compare the input to a VWM item than when they ignore the input (Experiment 1) or maintain the input in VWM alongside the target item (Experiment 2). Across both experiments, VWM reports revealed larger attraction biases toward the perceptual input following explicit perceptual comparisons relative to the control conditions. Furthermore, these attraction biases were selectively amplified when participants judged the perceptual input to be similar, rather than dissimilar, to the remembered item, even after controlling for physical feature distance and baseline memory precision across task conditions. Together, these findings demonstrate that perceptual comparisons actively modulate memory biases induced by new visual inputs above and beyond passive stimulus-driven interference.