Below are summaries of the some major research projects on which I have worked. Most of these studies have been completed. If you are looking for current opportunities to participate in research, please visit my “Current Research Page.”
1) Information Search Behaviors Associated with Symptoms of OCD
Recent theoretical models of obsessive-compulsive disorder (OCD) have emphasized a fundamental role for decision making deficits in the disorder, and emerging neurobiological findings suggest that OCD is associated with functional abnormalities in the way the brain processes decision-relevant information. Prior studies have found that OCD is associated with a tendency to defer decisions until a greater quantity of decision-relevant information has been acquired. This study sought to assess the effects of information cost on information acquisition and to model information purchases using simple decisional heuristics drawn from the cognitive science literature. Participants with varying levels of obsessive-compulsive (OC) symptoms completed a multiattribute decision making task in which they could purchase decision-relevant information from 5 differentially-useful sources. Higher OC symptoms were associated with more errors, inconsistent choices, and a random response style. OC symptoms also were associated with reduced cue order perseveration and increased search order reorganization, particularly during later training blocks; these findings remained statistically significant even after controlling for differences in indecisiveness, intolerance of uncertainty, perfectionism, and total errors. OC symptoms were unrelated to total earnings, information purchases, cue deliberation times (i.e., latencies), or the number of decisions consistent with one-reason decision making. Moreover, OC symptoms were unrelated to the acquisition of cue orders that reflected environmental validity, discrimination, or success ratios. Overall, the Tally Swap heuristic obtained the best fit for participant data. Higher OC symptoms were associated with poorer fit of the Tally Swap heuristic for predicting information purchases during later decision trials; no group differences in fit were observed for the Take the Last, Tally, or Validity heuristics. Finally, higher OC symptoms were associated with greater indecision, intolerance of uncertainty, perfectionism, and a greater tendency to maximize ideal outcomes and avoid regret. Potential neurocognitive explanations for these findings (e.g., selective attention, working memory, planning, underlying neural circuitry) are discussed. This study advances our understanding of multiattribute decision making in obsessive-compulsive disorder and provides some of the first evidence linking individual differences in information search behavior to psychopathology.
2) Social Information Processing Laboratory, Indiana University
A) Obsessive-compulsive personality characteristics relate to differences in associative learning during a visual discrimination-conditioning paradigm. Although many of the hallmark features of OCD are cognitive in nature, recent empirical evidence suggests that these symptoms might emerge from alterations in basic learning processes. Individual differences in learning that have been implicated in OCD include: 1) an enhanced ability to form associations to neutral stimuli, and 2) abnormalities in the ability to discriminate between different types of stimuli (e.g., “safe” and “unsafe” stimuli). This study was an empirical investigation of how well individuals who exhibit elevated OCD-like characteristics are able to discriminate between simple visual stimuli. Our results suggest that OCD is associated with intact discrimination conditioning initially during training, but the ability to discriminate between stimuli becomes impaired as training progresses.
B) Infrared and electromyogram measures of the eyeblink response: A search for convergence. There is a general lack of consensus regarding the most appropriate methodological tool for quantifying basic psychophysiological processes (e.g., classical conditioning) and responses (e.g., the acoustic startle response). This study compared the usefulness of infrared (IR) versus electromyogram (EMG) recording techniques for quantifying human eyeblink responses. The results of this study suggest that EMG is a more sensitive tool for detecting eyeblink responses, but IR may be preferable for characterizing changes in response amplitudes.
3) Personality and Affect Laboratory, University of Miami
Psychopathy has been associated with abnormalities in the processing of affective stimuli; these differences have been particularly pronounced within the context of environmental rewards and punishments. In this study, we recorded the startle responses of individuals exposed to acoustic probes during the presentation of positive, negative, and neutral picture stimuli. We found that individuals exhibiting elevated psychopathic characteristics showed a blunted immediate threat response in comparison to controls.
4) Department of Anatomy and Neurobiology, Washington University
One goal of neuroscience is to better understand the cellular and molecular mechanisms involved in neural development and plasticity. This study assessed one activity-independent mechanism thought to guide neural migration. Using biochemical assays including PAGE electrophoresis and Western blotting, we studied the process by which slit-mediated axonal repulsion takes place.
5) Mood and Dating Study, University of Miami
Social relationships have been shown to moderate symptoms of psychopathology. In this study, we used indicators of social functioning to predict anxiety and depression in adolescents. We found a significant association between positive relationships (i.e., positive friendships and dating relationships) and reduced social anxiety. Furthermore, affiliation with a high-status peer crowd was associated with reduced depressive symptoms.