Our research interests center on brain mechanisms of perception, attention and decision making. We use a combination of psychophysics, electrophysiology, functional imaging and computational modeling to study these mechanisms in the human brain.
Our focus is on paradigm development and basic research findings, but we continually deploy our paradigms and dependent measures to studies of neurological and psychiatric disorders through several active clinical collaborations.
Our current research questions and projects include:
Neural mechanisms of decision making: Almost all of our interactions with the environment boil down to a series of decisions, involving sensing and accumulating “evidence” and preparing and executing appropriate actions that further our goals. In collaboration with Redmond O’Connell of Trinity College Dublin, we have developed paradigms that allow us to isolate neural signals responsible for each of several levels of neural processing that engage in forging simple decisions. We are now building on these paradigm innovations to study a range of fundamental aspects of decision making, such as how we adapt to different environmental contingencies, how different kinds of evidence are integrated in forming decisions, and how brain mechanisms of attention and motor preparation interact with the process of evidence accumulation. We also examine how the relative value of competing options is represented and factored into mechanisms of very rapid decision making in dynamic contexts.
Neural mechanisms of attention: when you know something about a sensory event before it happens, you’re better at parsing that event to get the information you need, for the situation you’re in. This ability is known as selective attention. We know that the underlying brain mechanisms involve alteration of activity in the brain’s sensory hardware, but the details of this alteration remain a mystery. For example, under what special conditions will attention cause a change in neural activity at the very moment sensory information hits the cortex? We are currently resolving these details through quantitative characterization of behavior and careful manipulation of task demands, drawing on principles of sensory physiology and computational models of perceptual decision making.
Even when doing simple tasks, behavioral performance fluctuates and errors occur. Sometimes the brain’s sensory analyzers are just not good enough. Other times, we just drift off the task through mind-wandering or simply because we momentarily loosen our focus. What’s going on in the brain when this happens, and to what degree does it depend on the nature of the task at hand?
Neural signals of the visual system: Even the most basic aspects of visual processing are extremely difficult to parse in noninvasively measured neuro-electric signals on the human scalp. We develop paradigms and simple signal-analysis approaches based on basic principles of sensory physiology to allow derivation of reliable and specific indices of visual encoding. We apply these paradigms to examine basic mechanisms of contrast and feature perception, contextual interactions, and the impact of task-dependent, top-down attention on visual representations.