Three groups of adults (mean ages 22, 43, and 68 years) listened to a list containing 30 words that were repeated from zero to seven times each. The subjects were then tested for their sensitivity to differences in frequency of occurrence. Au groups were found to be equally sensitive to frequency information. Prior knowledge about the exact nature of the forthcoming test did not affect performance. These results are interpreted in light of a theory that suggests that performance is determined by at least two factors: the cognitive capacity that an individual has available, and the capacity demands imposed by the task.