In the real world, it is very rare for a single target suddenly to pop into view. In general, there are many potential stimuli that compete for our attention, and the decision to select one of them is the result of competitive interactions between multiple LATER units (Mackay, Cerf et al. 2012, Tatler, Brockmole et al. 2017). But before we deal with this kind of spatial complexity, we need to consider a particular aspect of temporal complexity. How do targets interact when presented sequentially rather than simultaneously?