Abstract

Most psychological models of perceptual decision making are of the accumulation-to- threshold variety. The neural basis of accumulation in parietal and prefrontal cortex is therefore a topic of great interest in neuroscience. In contrast, threshold mechanisms have received less attention, and their neural basis has usually been sought in subcortical structures. Here I analyze a model of a decision threshold that can be implemented in the same cortical areas as evidence accumulators, and whose behavior bears on two open questions in decision neuroscience: (1) When ramping activity is observed in a brain region during decision making, does it reflect evidence accumulation? (2) Are changes in speed-accuracy tradeoffs and response biases more likely to be achieved by changes in thresholds, or in accumulation rates and starting points? The analysis suggests that task-modulated ramping activity, by itself, is weak evidence that a brain area mediates evidence accumulation as opposed to threshold readout; and that signs of modulated accumulation are as likely to indicate threshold adaptation as adaptation of starting points and accumulation rates. These conclusions imply that how thresholds are modeled can dramatically impact accumulator-based interpretations of this data.

Publisher

Frontiers Research Foundation

Publication Date

6-21-2012

Publication Title

Frontiers in Psychology

Department

Neuroscience

Document Type

Article

DOI

10.3389/fpsyg.2012.00183

Keywords

Decision, Threshold, Accumulator, Integration, Switch, Reward, Sequence

Document Version

published

Language

English

Format

text

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