This article examines the possibility that the visal system treats dynamic cues a instances of new perceptual objects undersome circumstances. Using the contingent capture paradigm (C. L. Folk, R. W. Remington, & J. C. Johnston, 1992), the author compared luminance change cues of different magnitude for their ability to capture attention when participants were set for new objects. Wheras small luminance changes failed to produce attentional capture, large luminance changs indeed captured attention, suggesting that they were treated as compatible with the participants' attentional set for new objects. It is argued that sufficiently large luminance transients led to a disurption of spatiotemporal object continuity and precipitated the emergence of a new perceptual object.