OBJECTIVE: We investigate the impact of event uncertainty, decision support (DS) display format, and DS sensitivity on participants' behavior, performance, subjective workload, and perception of DS usefulness and performance in a classification task. BACKGROUND: DS systems can positively and negatively affect decision accuracy, performance time, and workload. The ability to access DS selectively, based on informational needs, might improve DS effectiveness. METHOD: Participants performed a sensory classification task in which they were allowed to request DS on a trial-by-trial basis. DS was presented in separated-binary (SB), separated-likelihood (SL), or integrated-likelihood (IL) formats. Access preferences, task performance, performance time, subjective workload, and perceived DS usefulness and performance were recorded. RESULTS: Participants accessed DS more often when it was highly sensitive, stimulus information was highly uncertain, or the DS cue and stimulus information were perceptually integrated. Effective sensitivity was highest with the integrated likelihood DS. Although the separated likelihood DS provided more information than the binary likelihood DS, it was accessed less often, leading to lower sensitivity. CONCLUSION: Participants are most likely to access DS when raw stimulus information is highly uncertain and appear to make effective use of likelihood DS only when DS cues are integrated with raw stimulus information within a display. APPLICATION: Results suggest that DS use will be most effective when likelihood DS cues and raw stimulus information are perceptually integrated. When DS cues and raw stimuli cannot be perceptually integrated, binary cues from the DS will be more effective than likelihood cues.