Gallistel argues that the reason the group learning curves look to be smooth and gradual is that there are large individual differences between subjects in terms of when the onset latency of the step-wise curves begin (Gallistel et al. 2004: 13125); in other words, different animals take different amounts of time for the learning to commence. The differences between individual subject’s learning curves are predicated on when the steps begin and not by the speed of the individual animal’s learning process. All individuals appear to show rapid rises in learning, but since each begins their learning at a different time, when we average over the group, the rapid step-wise learning appears to look like slow, gradual learning (Gallistel et al. 2004: 13124).