Where does prepotency come from on developmental tests of inhibitory control?

Understanding the processes that make responses prepotent is central to understanding the role of inhibitory control in cognitive development. The question of what makes responses prepotent was investigated using the two most widely studied measures of preschoolers' inhibitory control. Across two experiments, 80 children were tested either on a series of stimulus-response compatibility (SRC) tasks or on a series of Go/No-go tasks. Results indicated that high levels of prepotency on SRC tasks (such as the Day/Night task) occur only under specific conditions; making a verbal response can be highly prepotent if the stimulus and response are associated with each other (e.g., saying "cup" to a cup) but is less prepotent when they are unassociated (e.g., saying "cup" to a doorstop). Action responses (e.g., lifting a cup to your mouth) show little prepotency irrespective of whether the stimulus and response are associated. In contrast, with Go/No-go tasks, a much wider variety of behaviors are highly prepotent regardless of whether the stimulus and response are associated. These data suggest that prepotency arises in very different ways, depending on the type of task used. Although both Go/No-go tasks and SRC tasks can make inhibitory demands, they do so for fundamentally different reasons.