Bachelor of Science, University of Michigan Ann Arbor (2008)
Doctor of Philosophy, Vanderbilt University (2014)
Russell Poldrack, Postdoctoral Faculty Sponsor
Large-scale analysis of test-retest reliabilities of self-regulation measures.
Proceedings of the National Academy of Sciences of the United States of America
The ability to regulate behavior in service of long-term goals is a widely studied psychological construct known as self-regulation. This wide interest is in part due to the putative relations between self-regulation and a range of real-world behaviors. Self-regulation is generally viewed as a trait, and individual differences are quantified using a diverse set of measures, including self-report surveys and behavioral tasks. Accurate characterization of individual differences requires measurement reliability, a property frequently characterized in self-report surveys, but rarely assessed in behavioral tasks. We remedy this gap by (i) providing a comprehensive literature review on an extensive set of self-regulation measures and (ii) empirically evaluating test-retest reliability of this battery in a new sample. We find that dependent variables (DVs) from self-report surveys of self-regulation have high test-retest reliability, while DVs derived from behavioral tasks do not. This holds both in the literature and in our sample, although the test-retest reliability estimates in the literature are highly variable. We confirm that this is due to differences in between-subject variability. We also compare different types of task DVs (e.g., model parameters vs. raw response times) in their suitability as individual difference DVs, finding that certain model parameters are as stable as raw DVs. Our results provide greater psychometric footing for the study of self-regulation and provide guidance for future studies of individual differences in this domain.
View details for DOI 10.1073/pnas.1818430116
View details for PubMedID 30842284
Dopaminergic medication shifts the balance between going and stopping in Parkinson's disease
2018; 109: 262–69
The present behavioral study delineates the impact of Parkinson's disease (PD) and of dopaminergic medication on action control over voluntary behavior. Previous studies reported either prolonged responding or stopping latencies in PD compared to healthy controls (HC). Few studies investigated the effects of dopaminergic medication on these processes concurrently. We administered a stop-change task, an extended version of the stop task, that required (i) speeded responding to a go signal (i.e., going), (ii) inhibiting ongoing motor responses (i.e., stopping), and (iii) changing to an alternative response. PD performance (n = 33) was collected once during regular dopaminergic medication conditions (On state) and once after a medication washout period (Off state). A group of age-matched HC (n = 21) performed the stop-change task once. Response latencies to go signals were comparable between HC and PD Off, indicative of unimpaired going. Compared to HC, PD Off showed prolonged stopping latencies. Within the clinical group, stopping latencies significantly improved after taking dopaminergic medication. Interestingly, the shorter stopping latencies observed in the On state were paralleled by longer response latencies to go signals. The degree of the inhibition improvement observed in the medication state was correlated with the degree of response slowing. Change RT did not vary between groups or between medication states. These patterns of results are discussed in terms of a tradeoff between going versus stopping of motor responses in PD patients. Shifts of this tradeoff seem to be driven by dopaminergic medication, which has potential clinical implications.
View details for DOI 10.1016/j.neuropsychologia.2017.12.032
View details for Web of Science ID 000425202400027
View details for PubMedID 29269306
Identifying Stimuli That Cue Multiple Responses Triggers the Congruency Sequence Effect Independent of Response Conflict
JOURNAL OF EXPERIMENTAL PSYCHOLOGY-HUMAN PERCEPTION AND PERFORMANCE
2017; 43 (4): 677-689
According to most accounts of executive control, resisting distraction requires enhancing task-relevant processing, reducing task-irrelevant processing, or both. Consistent with this view, the congruency effect in Stroop-like tasks-a putative measure of distraction-is often smaller after highly distracting incongruent trials than after less distracting congruent trials. Competing accounts of executive control, however, differ on which aspect of an incongruent trial triggers this congruency sequence effect (CSE). The activation-suppression account posits the activation of an incorrect response. In contrast, the response cueing account posits identifying stimuli that cue multiple responses. To distinguish between these accounts, we conducted 2 experiments involving a modified prime-probe task wherein participants respond to the distracter in occasional catch trials. We found that the CSE is triggered by identifying stimuli that cue multiple responses, rather than by the activation of an incorrect response. Further, we observed this effect while ruling out an alternative "response conflict" trigger. These findings are more consistent with the response cueing account than with the activation-suppression account. (PsycINFO Database Record
View details for DOI 10.1037/xhp0000350
View details for Web of Science ID 000398914000005
View details for PubMedID 28095005
Applying novel technologies and methods to inform the ontology of self-regulation
Behaviour Research and Therapy
Self-regulation is a broad construct representing the general ability to recruit cognitive, motivational and emotional resources to achieve long-term goals. This construct has been implicated in a host of health-risk behaviors, and is a promising target for fostering beneficial behavior change. Despite its clear importance, the behavioral, psychological and neural components of self-regulation remain poorly understood, which contributes to theoretical inconsistencies and hinders maximally effective intervention development. We outline a research program that seeks to define a neuropsychological ontology of self-regulation, articulating the cognitive components that compose self-regulation, their relationships, and their associated measurements. The ontology will be informed by two large-scale approaches to assessing individual differences: first purely behaviorally using data collected via Amazon's Mechanical Turk, then coupled with neuroimaging data collected from a separate population. To validate the ontology and demonstrate its utility, we will then use it to contextualize health risk behaviors in two exemplar behavioral groups: overweight/obese adults who binge eat and smokers. After identifying ontological targets that precipitate maladaptive behavior, we will craft interventions that engage these targets. If successful, this work will provide a structured, holistic account of self-regulation in the form of an explicit ontology, which will better clarify the pattern of deficits related to maladaptive health behavior, and provide direction for more effective behavior change interventions.
View details for DOI 10.1016/j.brat.2017.09.014
View details for PubMedCentralID PMC5801197
Investigating motor initiation and inhibition deficits in patients with Parkinson's disease and freezing of gait using a virtual reality paradigm.
2016; 337: 153-162
Freezing of gait (FOG) is a common, disabling symptom of Parkinson's disease (PD) that is associated with deficits in motor initiation and inhibition. Understanding of underlying neurobiological mechanisms has been limited by difficulties in eliciting and objectively characterizing such gait phenomena in the clinical setting. However, recent work suggests that virtual reality (VR) techniques might offer the potential to study motor control. This study utilized a VR paradigm to explore deficits in motor initiation and stopping performance, including stop failure in PD patients with (Freezers, 31) and without (Non-Freezers, 23) FOG, and healthy age-matched Controls (15). The VR task required subjects to respond to a series of start and stop cues while navigating a corridor using ankle flexion/extension movements on foot pedals. We found that Freezers experienced slower motor output initiation and more frequent start hesitations (SHs) (initiations greater than twice a subject's usual initiation latency) compared to Non-Freezers and Controls. Freezers also showed more marked inhibitory impairments, taking significantly longer to execute motor inhibition, and experiencing an increased frequency of failed stopping in response to stop cues compared to Non-Freezers and Controls. Stopping impairments were exacerbated by stop cues requiring additional cognitive processing. These results suggest that PD patients with FOG have marked impairments in motor initiation and inhibition that are not prominent in patients without FOG, nor healthy controls. Future work combining such VR paradigms with neuroimaging techniques and intra-operative deep brain recordings may increase our understanding of these phenomena, promoting the development of novel technologies and therapeutic approaches.
View details for DOI 10.1016/j.neuroscience.2016.09.019
View details for PubMedID 27651150
The Dynamics of Functional Brain Networks: Integrated Network States during Cognitive Task Performance.
2016; 92 (2): 544-554
Higher brain function relies upon the ability to flexibly integrate information across specialized communities of brain regions; however, it is unclear how this mechanism manifests over time. In this study, we used time-resolved network analysis of fMRI data to demonstrate that the human brain traverses between functional states that maximize either segregation into tight-knit communities or integration across otherwise disparate neural regions. Integrated states enable faster and more accurate performance on a cognitive task, and are associated with dilations in pupil diameter, suggesting that ascending neuromodulatory systems may govern the transition between these alternative modes of brain function. Together, our results confirm a direct link between cognitive performance and the dynamic reorganization of the network structure of the brain.
View details for DOI 10.1016/j.neuron.2016.09.018
View details for PubMedID 27693256
View details for PubMedCentralID PMC5073034
The Experiment Factory: Standardizing Behavioral Experiments
FRONTIERS IN PSYCHOLOGY
The administration of behavioral and experimental paradigms for psychology research is hindered by lack of a coordinated effort to develop and deploy standardized paradigms. While several frameworks (Mason and Suri, 2011; McDonnell et al., 2012; de Leeuw, 2015; Lange et al., 2015) have provided infrastructure and methods for individual research groups to develop paradigms, missing is a coordinated effort to develop paradigms linked with a system to easily deploy them. This disorganization leads to redundancy in development, divergent implementations of conceptually identical tasks, disorganized and error-prone code lacking documentation, and difficulty in replication. The ongoing reproducibility crisis in psychology and neuroscience research (Baker, 2015; Open Science Collaboration, 2015) highlights the urgency of this challenge: reproducible research in behavioral psychology is conditional on deployment of equivalent experiments. A large, accessible repository of experiments for researchers to develop collaboratively is most efficiently accomplished through an open source framework. Here we present the Experiment Factory, an open source framework for the development and deployment of web-based experiments. The modular infrastructure includes experiments, virtual machines for local or cloud deployment, and an application to drive these components and provide developers with functions and tools for further extension. We release this infrastructure with a deployment (http://www.expfactory.org) that researchers are currently using to run a set of over 80 standardized web-based experiments on Amazon Mechanical Turk. By providing open source tools for both deployment and development, this novel infrastructure holds promise to bring reproducibility to the administration of experiments, and accelerate scientific progress by providing a shared community resource of psychological paradigms.
View details for DOI 10.3389/fpsyg.2016.00610
View details for Web of Science ID 000374735800001
View details for PubMedID 27199843
View details for PubMedCentralID PMC4844768
- Generalized motor inhibitory deficit in Parkinson's disease patients who freeze JOURNAL OF NEURAL TRANSMISSION 2015; 122 (12): 1693-1701