The ``less is more'' hypothesis suggests that one reason adults and children differ in their language acquisition abilities is that they also differ in other cognitive capacities. According to one version, children's relatively poor memory may make them more likely to over-regularize inconsistent input (Hudson Kam & Newport 2005, 2009). This paper investigates this hypothesis experimentally and computationally. Experiments in which adults were placed under a high cognitive load during a language-learning task reveal that in adults, increased load does not result in increased over-regularization. A computational model offers a possible explanation for these results, demonstrating that over-regularization should occur only in the presence of memory limitations as well as a strong prior bias for over-regularization. Taken together, these findings suggest that the difference in over-regularization between adults and children may not be attributable solely to differences in memory capacity between the two groups.