James Sorenson

Katharina Kircanski, Renee J Thompson, James Sorenson, Lindsey Sherdell, Ian H Gotlib (2017)

Rumination and worry are two perseverative, negatively valenced thought processes that characterise depressive and anxiety disorders. Despite significant research interest, little is known about the everyday precipitants and consequences of rumination and worry. Using an experience sampling methodology, we examined and compared rumination and worry with respect to their relations to daily events… Show more

Katharina Kircanski, Renee J Thompson, James Sorenson, Lindsey Sherdell, Ian H Gotlib (2017)

Rumination and worry are two perseverative, negatively valenced thought processes that characterise depressive and anxiety disorders. Despite significant research interest, little is known about the everyday precipitants and consequences of rumination and worry. Using an experience sampling methodology, we examined and compared rumination and worry with respect to their relations to daily events and affective experience. Participants diagnosed with Major Depressive Disorder (MDD), Generalized Anxiety Disorder (GAD), co-occurring MDD–GAD, or no diagnosis carried an electronic device for one week and reported on rumination, worry, significant events, positive affect (PA), and negative affect (NA). Across the clinical groups, occurrences of everyday events predicted subsequent increases in rumination, but not worry. Further, higher momentary levels of rumination, but not worry, predicted subsequent decreases in PA and increases in NA. Thus, in these clinical groups, rumination was more susceptible to daily events and produced stronger affective changes over time. We discuss implications for theory and clinical intervention.

Show less

Major Depressive Disorder (MDD) is a psychiatric mood disorder that is associated with abnormal cognitive processes, including overgeneral memory (OGM) for autobiographical events. When asked to produce memories from their own lives, depressed individuals produce fewer specific memories than do their nondepressed peers. The neural basis of OGM in MDD, however, is not yet clear. Specifically, we do not know if depressed individuals exhibit normal memory-related neural activation during encoding;… Show more

Major Depressive Disorder (MDD) is a psychiatric mood disorder that is associated with abnormal cognitive processes, including overgeneral memory (OGM) for autobiographical events. When asked to produce memories from their own lives, depressed individuals produce fewer specific memories than do their nondepressed peers. The neural basis of OGM in MDD, however, is not yet clear. Specifically, we do not know if depressed individuals exhibit normal memory-related neural activation during encoding; we also do not know if individuals with MDD show neural signatures that have been found to be related to retrieval of content, i.e. cortical reinstatement. To address these questions, depressed and nondepressed adults completed a standard measure of autobiographical memory specificity and, inside a Magnetic Resonance Imaging (MRI) scanner, a paired-associates learning task. At the behavioral level, depressed individuals showed evidence of decreased specificity of autobiographical memory relative to healthy controls, but did not exhibit impairment in associative learning. At the neural level... compared to their nondepressed peers, depressed individuals showed less activity in the right prefrontal cortex during the successful retrieval of images. In addition, and also counter to hypotheses, there was robust evidence of cortical reinstatement of image category information in both depressed and nondepressed individuals. Together, these findings suggest that OGM in MDD is not related to an inability to reactivate visual information or to an inability to form or encode associative memories. Instead, it seems that if OGM in MDD is related to some systematic aberrant neural function, this abnormality is a subtle difference between depressed and nondepressed individuals in retrieval processes that is mediated by the prefrontal cortex. Show less

Major depressive disorder (MDD) is associated with biases in memory, including poor memory for positive stimuli. It is unclear, however, if this impaired memory for positive stimuli in MDD is related to difficulties in the initial processing of stimuli, or alternatively, reflects a decreased ability to draw on memories of positive stimuli after they have been formed. Using two versions of a word-matching task that featured a mixture of novel and practiced emotionally valenced words, we found… Show more

Major depressive disorder (MDD) is associated with biases in memory, including poor memory for positive stimuli. It is unclear, however, if this impaired memory for positive stimuli in MDD is related to difficulties in the initial processing of stimuli, or alternatively, reflects a decreased ability to draw on memories of positive stimuli after they have been formed. Using two versions of a word-matching task that featured a mixture of novel and practiced emotionally valenced words, we found that depressed individuals experienced greater difficulty learning positively valenced information than did their nondepressed peers. This difficulty seemed to be specific to initial encounters with the novel, but not the practiced, positive stimuli. These findings suggest that memory deficits for positive information associated with depression are related to how this information is initially processed. Implications of these findings for interventions are discussed and directions for future research are advanced. Show less

A/B testing is an important decision making tool in product development because can provide an accurate estimate of the average treatment effect of a new features, which allows developers to understand how the business impact of new changes to products or algorithms. However, an important assumption of A/B testing, Stable Unit Treatment Value Assumption (SUTVA), is not always a valid assumption to make, especially for products that facilitate interactions between individuals. In contexts like… Show more

A/B testing is an important decision making tool in product development because can provide an accurate estimate of the average treatment effect of a new features, which allows developers to understand how the business impact of new changes to products or algorithms. However, an important assumption of A/B testing, Stable Unit Treatment Value Assumption (SUTVA), is not always a valid assumption to make, especially for products that facilitate interactions between individuals. In contexts like one-to-one messaging we should expect network interference; if an experimental manipulation is effective, behavior of the treatment group is likely to influence members in the control group by sending them messages, violating this assumption. In this paper, we propose a novel method that can be used to account for network effects when A/B testing changes to one-to-one interactions. Our method is an edge-based analysis that can be applied to standard Bernoulli randomized experiments to retrieve an average treatment effect that is not influenced by network interference. We develop a theoretical model, and methods for computing point estimates and variances of effects of interest via network-consistent permutation testing. We then apply our technique to real data from experiments conducted on the messaging product at LinkedIn. We find empirical support for our model, and evidence that the standard method of analysis for A/B tests underestimates the impact of new features in one-to-one messaging contexts. Show less