When a single perceptual object provides two different reasons for a particular decision (by containing two qualitatively different targets), detailed analyses of the response-time distributions have shown that the two different reasons are jointly responsible for the final decision. The question is whether this coactivation occurs because the two targets contained by the object were from separate dimensions (e.g., color and shape) or were parts of the same perceptual object. Early work argued in favor of dimensions, implying that the types of information being processed is critical, as opposed to their sources; more recent work has argued in favor of objects. Experiment 1 in the present paper corrected for a potential bias in the design of some recent studies and found additional evidence in favor of objects. Two additional experiments directly manipulated whether redundant targets would be perceived as parts of one or two perceptual objects (while holding all else constant) and produced the strongest evidence to date that coactivation requires that the redundant targets be parts of one object. This reverses the original conclusion and suggests that the sources of information are critical, as opposed to the types. Two specific versions of the objectbased model are discussed.Keywords Divided attention . Perceptual dimensions . Perceptual objects People must often make rapid decisions in situations where there is more than one piece of relevant information. These situations vary from the mundane, such as deciding between paper or plastic at the supermarket checkout (where both convenience and environmental impact are relevant), to the highly stressful, such as deciding whether to swerve to the left or the right when faced with a deer in the road (where both traction and on-coming traffic are relevant). One of the most basic questions that arise in the study of how rapid decisions are made is the manner in which multiple pieces of information are processed. Is all of the evidence in favor of a particular behavior combined in some way, or does one piece of evidence take near-total control, in something akin to a winner-take-all? Or it is not as simple as one or the other -does the manner in which multiple pieces of information are processed depend on the sources or the types of information? These questions can all be addressed by the use of the redundant-targets detection task (for an introduction, see Miller, 1982, or Mordkoff & Yantis, 1991. The answers to these questions tell us much about the functional architecture of the human informationprocessing system, as well as how to design and build better devices to provide information to people who are faced with time-limited decisions.Within the information-processing literature, the idea that multiple pieces of redundant information are somehow combined to activate a single decision is known as the coactivation model (e.g., Miller, 1982;Schwarz, 1989). The alternative idea, under which the strongest or fastest piece of information is wholly responsible fo...