Presentation

Gabriel Cler¹, Samantha Bartolo¹; ¹University of Washington

Developmental language disorder (DLD) is a common neurodevelopmental disorder characterized by unexplained deficits in expressive and/or receptive components of language. One ongoing question about this language difference is what underlying domains of memory and learning might be affected, and what these differences would imply about expected neural differences. Two prominent theories suggest there are deficits in all procedural learning (Ullman et al., 2020; Ullman & Pierpont, 2005) or just sequence-based procedural learning (Gerken et al., 2021; Hsu & Bishop, 2014) in DLD. Individuals with DLD are also noted to have poorer fine and gross motor skills (Diepeveen et al., 2018; Hill, 2001). Importantly, the tasks used to assess learning commonly rely on motor skills both for acquiring and demonstrating learning, possibly muddying interpretation of the results. In this study, we used two sequence-based implicit learning tasks to explore the influence of manual motor output demands on learning. Participants completed two common sequential learning tasks, a serial reaction time (SRT) task and a visual statistical learning (VSL) task. The SRT task measured participants’ ability to implicitly learn a visually-presented, 10-element sequence via manual motor output (i.e., keystrokes on a keyboard). Learning was assessed by the difference in reaction time of correct keypresses in the final block of random presses and the final block of sequence presses. The visual statistical learning task required participants to monitor a stream of shapes that were organized into repeating triplets and then report which triplets seemed more familiar. We hypothesized that adults with DLD would perform worse on the motor-dependent sequential learning task when compared to adults without language difficulties, but would perform similarly on the sequential learning task in which manual motor output was not required. Adults age 18-45 completed language testing to determine language status (Fidler et al., 2011) before completing both tasks. Although online data collection is ongoing, visual inspection of our initial results (comparison group N=19; DLD group N=4) indicates that the DLD group performs worse on the SRT task and equivalently on the VSL task, consistent with our hypotheses. Once our dataset reaches the targeted recruitment based on a priori power analyses (N=21 per group), we will statistically evaluate group differences with t-tests. Results will add to our understanding of DLD regardless of the final statistical results. Significant differences on both SRT and VSL would be consistent with other sequence-based deficit hypotheses (Gerken et al., 2021; Ullman et al., 2020). Differences on only the SRT and not the VSL task would confirm our hypotheses and suggest that manual motor demands mediate (the interpretation of deficits in) implicit learning in adults with DLD. No group differences on both tasks would suggest that differences in sequential learning of these types, if any, were smaller than we were able to detect, and follow-up studies would be needed to explore the interaction of DLD and motor demands more fully. This study contributes to the existing literature by exploring the influence of motor demands on a common concern in DLD, sequential learning.

Topic Areas: Disorders: Developmental, Multisensory or Sensorimotor Integration