Temporal Processing in Auditory Perceptual Grouping and Decision-Making
How do perceptual decision-making and auditory perceptual grouping interact on a perceptual, computational, and neural level? The work in this dissertation lays the groundwork to investigate the neural basis for auditory perceptual decisions by examining the perceptual and computational effects of the temporal structure of an auditory stimulus. I examined the role of auditory perceptual grouping on auditory perceptual judgments by asking whether the presentation rate of a stimulus sequence, which can affect the perceptual grouping of the stimulus, affects how sensory evidence converted into a decision. I devised a task that allows us to test, under different grouping conditions, whether the observed performance was consistent with changes in the representation of sensory evidence used to make the perceptual judgment or in the process by which the sensory evidence is converted into the decision. Subjects made a judgment on the frequency changes over time of a tone sequences while the interburst interval (IBI), or the time between tones of the stimulus, was varied across trials. I examined how subjects processed the sensory evidence to form their decisions as well as modeled the effect of IBI on their decision-making process. The results show that subjects accumulated sensory evidence over time to form their judgment and while IBI and perceived grouping did not affect the accumulation rate, subjects accumulated less total sensory evidence for long IBIs consistent with a collapsing decision boundary. By understanding how the brain converts sensory stimuli into a perceptual decision with our task, we can better understand the computational principles and the neural implementation of how auditory percepts are formed.