This study explores communication differences between older and younger users with a task-oriented spoken dialogue system. Previous analyses of the MATCH corpus show that older users have significantly longer dialogues than younger users and that they are less satisfied with the system. Open questions remain regarding the relationship between information recall and cognitive abilities. This study documents a length annotation scheme designed to explore causes of additional length in the dialogues and the relationships between length, cognitive abilities, user satisfaction, and information recall. Results show that primary causes of older users’ additional length include using polite vocabulary, providing additional information relevant to the task, and using full sentences to respond to the system. Regression models were built to predict length from cognitive abilities and user satisfaction from length. Overall, users with higher cognitive ability scores had shorter dialogues than users with lower cognitive ability scores, and users with shorter dialogues were more satisfied with the system than users with longer dialogues. Dialogue length and cognitive abilities were significantly correlated with information recall. Overall, older users tended to use a human-to-human communication style with the system, whereas younger users tended to adopt a factual interaction style.