International audience When humans carry out actions in response to external stimulation, they acquire associations between the stimulus and the action it triggered. Previous research suggests that visuomotor integration and S-R learning is modulated by positive and negative action eVects. We present an experiment corroborating this notion. Participants switch between two semantic classiWcation tasks. In one task, correct responses triggered presentation of a positive or negative emotionally arousing picture. When the same target items were later on presented in the other task, performance was more impaired for stimuli previously followed by a positive picture than for stimuli previously followed by a negative picture. This suggests that the association between the stimulus and the task previously performed in response to the stimulus was stronger in the former than in the latter case, resulting in stronger conXict when the stimulus was presented in a new task context. Implications of this result for research on visuomotor integration and S-R learning are discussed.