Cognitive uncertainty is evidenced across learning, memory, and decision-making tasks. Uncertainty has also been examined in studies of positive affect and preference by manipulating stimulus presentation frequency. Despite the extensive research in both of these areas, there has been little systematic study into the relationship between affective and cognitive uncertainty. Using a categorization task, the present study examined changes in cognitive and affective uncertainty by manipulating stimulus presentation frequency and processing focus (i.e., promotion v. prevention focus). Following training, participants categorized stimuli and provided ratings of both typicality and negative affect. Results indicated that cognitive uncertainty was influenced by a categorical representation of stimuli whereas affective uncertainty was also influenced by exemplar presentation frequency during training. We additionally found that when the training was framed in terms of the avoidance of errors (i.e., a prevention focus), categorization performance was affected across the stimulus continuum whereas affective ratings remained unchanged.