Sources of individual differences in the speed of naming objects and actions: the contribution of executive control

We examined the contribution of executive control to individual differences in response time (RT) for naming objects and actions. Following Miyake et al., executive control was assumed to include updating, shifting, and inhibiting abilities, which were assessed using operation span, task-switching, and stop-signal tasks, respectively. Experiment 1 showed that updating ability was significantly correlated with the mean RT of action naming, but not of object naming. This finding was replicated in experiment 2 using a larger stimulus set. Inhibiting ability was significantly correlated with the mean RT of both action and object naming, whereas shifting ability was not correlated with the mean naming RTs. Ex-Gaussian analyses of the RT distributions revealed that updating ability was correlated with the distribution tail of both action and object naming, whereas inhibiting ability was correlated with the leading edge of the distribution for action naming and the tail for object naming. Shifting ability provided no independent contribution. These results indicate that the executive control abilities of updating and inhibiting contribute to the speed of naming objects and actions, although there are differences in the way and extent these abilities are involved.