Our interest in interval timing includes both the cognitive components (e.g., clock, memory, and decision stages) and neural substrates underlying these components and uses normal control (children, college students, and aged) and patient populations. Although research with normal participants is important for specifying the characteristics of the normal internal clock, work with patient populations who may show interval timing deficits offers the potential to further expand our understanding of the internal clock mechanisms.

One issue with studies of cognitive processing in patient populations, however, is whether or not performance deficits are actually a consequence of a failure to understand and follow task instructions. Such concerns also sometimes extend to studies of the very old or the very young. Recently, we have also been using interval-timing tasks in which participants are not explicitly instructed to time. In some cases the task requires a behavioral response (e.g., the Stop Reaction Time task) and in others it does not (e.g., pre-attentive interval timing). During pre-attentive timing, participants attend to some foreground task such as watching a silent movie while in the background a sound sequence with a regular temporal structure is played. Occasionally, the regular temporal structure is violated and whether not the brain detects this violation can be determined using electrophysiological and event-related optical brain imaging measures. These electrophysiological and optical brain imaging measures therefore provide a means to determine the characteristics of the timing system at a very early processing level.