Defining Embodied Characteristics of Decision Making in Attention Deficit Hyperactivity Disorder

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ABSTRACT Attention deficit hyperactivity disorder (ADHD) is well-characterized in terms of cognitive deficits (e.g., executive function and cognitive control), but defects in perceptual and motor functions are also frequent characteristics of the condition. These functions present an important avenue for research because perception and action occur upstream and downstream, respectively, of canonical high-level impairments. Basic research to date has provided the methodological and theoretical foundations necessary to study these integrated processes, and several paradigms now exist under an embodied choice framework—describing the processes by which decision making computations can be revealed through, and retroactively influenced by, movement characteristics (e.g., during reaching movements towards competing choices). Many individuals with ADHD exhibit motor hyperactivity and other motor symptoms (e.g., reaction time variability), making this study well-suited for a better understanding of the cognition-action pathways underlying psychopathology. Additionally, it has been shown by work in my co-sponsor’s laboratory (Dr. Julie Schweitzer) that movement can confer cognitive benefits to children with ADHD performing cognitive control tasks. Aim 1 is an investigation into the potential benefit of movement conveyed to adults with ADHD during a temporal discrimination task (i.e., a two-alternative forced choice long/short discrimination of a range of durations). A previous study in our laboratory utilized this paradigm and showed that healthy young volunteers benefited from concurrent movement during temporal discrimination. In this Aim, bridging work from my sponsors’ laboratories (Drs. Joiner and Schweitzer), we hypothesize that the beneficial effect of movement will be larger in individuals with ADHD. In Aim 2, we will observe how movement reflects the parallel evaluation of two integrated stimulus dimensions that converge on a single choice in a four- alternative forced choice task. Here the stimulus dimensions map directly onto physical dimensions; the targets are arranged in a square array equidistant from the start location. This novel task design will allow us to observe in real-time (via the movement trajectory) the way that stimulus uncertainty and viewing time guide choice. Each stimulus will always have one high-certainty dimension (i.e., easy) and one low-certainty (i.e., difficult) dimension (within-subject). We hypothesize that initial movement directions will reflect prioritization of the high-certainty dimension (i.e., biased toward the relevant Cartesian axis). The task will first be developed in healthy controls before its application to the ADHD and matched control groups from Aim 1. In the matched ADHD and control task, we hypothesize that individuals with ADHD will be less effective at prioritizing high-certainty information, and thus, initial movements will be less likely to cluster around the high certainty axis. This interdisciplinary project will use methods from motor control and clinical psychology to probe the integrated processes of sensory, decisional, and motoric characteristics of ADHD that are typically studied in isolation, and may inform diagnostic and treatment methods to improve the quality of life for people affected by this condition.