Response times

Our experiences from the recent past, even if no longer relevant, can powerfully shape our current choices. Such “serial dependence” has been observed ubiquitously in various cognitive phenomena [1]. Recent work suggests a causal role of the PPC in mediating serial dependence in rodents [2]; similar evidence in humans is correlative at best [3]. Does the PPC causally mediate serial dependence in humans? We analyzed data from participants (n=26) performing a spatially cued change detection task [4]. Participant received either 40-Hz transcranial alternating current stimulation (tACS) over the

…In mice, errors and biased responses cluster in time rather than occurring randomly, indicating that animals transition into and out of disengaged states over the course of an experimental session. What neural and physiological processes trigger these state transitions? Here, we investigated the role of pupil-linked arousal, as relatively high or low levels of arousal are associated with poor task performance, and there is evidence that the activity of ascending arousal systems triggers larges

Bayesian computations are intractable and expensive, but this is rarely accounted for in existing Bayesian observer models. In this work, we propose that a) the brain can only compute imprecise (noisy) estimates of likelihoods and posteriors, and, b) since computations are expensive, the brain actively chooses which computations to perform to refine such estimates. We call our framework approximate inference through active sampling (AIAS) and study its implications in N-alternative categorization. While it is common in Bayesian observer models to assume that the agent makes noisy measurements

Electrophysiological recordings during perceptual decision tasks in monkeys suggest that the degree of confidence in a decision is based on a simple neural signal produced by the neural decision process. Attractor neural networks provide an appropriate biophysical modeling framework, and account for the experimental results very well. However, it remains unclear whether attractor neural networks can account for confidence reports in humans. We present the results from an experiment in which participants are asked to perform an orientation discrimination task, followed by a confidence judgment.

Perceptuo-motor sequences that underlie our everyday skills from walking to language have higher-order dependencies such that the statistics of one sequence element depend on a variably deep window of past elements. We used a non-parametric, hierarchical, forgetful, Bayesian sequence model to characterize the multi-day evolution of human participants’ implicit representation of a serial reaction time task sequence with higher-order dependencies. The model updates trial-by-trial, and seamlessly combines predictive information from shorter and longer windows onto past events, weighting the windo

Previous work with complex memory span tasks, in which simple choice decisions are imposed between presentations of to-be-remembered items, shows that these secondary tasks reduce memory span. It is less clear how reconfiguring and maintaining various amounts of information affects decision speeds. We documented and replicated a non-linear effect of accumulating memory items on concurrent processing judgments, showing that this pattern could be made linear by introducing "lead-in" processing judgments prior to the start of the memory list. With lead-in judgments, there was a large and consiste

Our research investigates how processes of attention, visual working memory (VWM), and decision-making combine to translate perception into action. Within this framework, the role of VWM is to form stable representations of transient stimulus events that allow them to be identified by a decision process, which we model as a diffusion process. In psychophysical tasks, we find the capacity of VWM is well defined by a sample-size model, which attributes changes in VWM precision with set-size to differences in the number evidence samples recruited to represent stimuli. In the first part of the tal