PROJECT SUMMARY Developmental language disorder (DLD) describes the idiopathic disorder(s) of language that occurs in approximately 7% of the population. Although DLD is understudied in adulthood, it is clear that the communication challenges in DLD extend beyond adolescence. The barriers to educational and vocational achievement for adults with DLD include persistent difficulties in learning and memory. Recent work suggests that these difficulties with learning and memory include deficits in overnight memory consolidation. Thus, an effective support for learning and memory function in adults with DLD must include strategies for both overcoming initial challenges in learning, as well as in mitigating a deficit in consolidation of learned information. In this project, we combine insights from the neurobiology of learning and memory, chronobiology, and speech perception, to determine the optimal training schedule for perceptual memory retention in adults with and without DLD. We have two Aims in this project: First, we will recruit 240 adults (120 with/120 without DLD) to participate in a speech-perceptual training to take place in one of six different training schedules over 24 hours. We predict that our manipulation of training schedules will interact with circadian preference and timing relative to overnight consolidation, such that we may discover the optimal practice schedule for speech sound retention for adult learners with & without DLD. Our focus on speech-sound information will allow us to track the learning and memory of linguistic form that is relatively independent from preexisting knowledge; moreover, speech perception is also a known difficulty for individuals with DLD. Under our second aim, we will recruit an additional 300 adults (150 with/150 without DLD) in order to determine how optimal training schedules interact with reflexive and reflective learning strategies in adults with and without DLD. We will achieve this aim by tracking the time course of learning and retention in adults participating in reflexive and reflective categorization training in one of six training schedules. This will provide us with generalizable insights into optimal training schedules for learning targets beyond the speech domain. The knowledge to be gained from this work will contribute to the basic science of learning and memory in adults with and without DLD. In addition, the factors that influence the successful retention of speech have substantial implications for intervention practices for other developmental disorders in which speech representations are implicated (speech sound disorder, dyslexia).