The aim of the current study was to compare both incidental and explicit auditory learning of second language derivational morphology by measuring the accuracy and the reaction time of a grammaticality judgment task. Furthermore, the study was set up to examine the nature of acquired knowledge using subjective measures of awareness during the testing phases and postexperimental verbal reports. The delayed effects of learning were investigated by testing participants immediately after the learning and 1 week later also. The results showed a significant learning effect for the incidental and explicit learners immediately after exposure, but only the explicit learners maintained the learning effects a week later. Both types of learners showed no significant difference in the reaction time. Incidental learners primarily developed implicit knowledge, while explicit learners relied on explicit knowledge to a large extent, part of which became unconscious later. The differences of learning under incidental and explicit learning conditions are discussed in terms of the maintenance of knowledge.
