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- Title
A Two-Stage Process Model of Sensory Discrimination: An Alternative to Drift-Diffusion.
- Authors
Peng Sun; Landy, Michael S.
- Abstract
Discrimination of the direction of motion of a noisy stimulus is an example of sensory discrimination under uncertainty. For stimuli that are extended in time, reaction time is quicker for larger signal values (e.g., discrimination of opposite directions of motion compared with neighboring orientations) and larger signal strength (e.g., stimuli with higher contrast or motion coherence, that is, lower noise). The standard model of neural responses (e.g., in lateral intraparietal cortex) and reaction time for discrimination is drift-diffusion. This model makes two clear predictions. (1) The effects of signal strength and value on reaction time should interact multiplicatively because the diffusion process depends on the signal-to-noise ratio. (2) If the diffusion process is interrupted, as in a cued-response task, the time to decision after the cue should be independent of the strength of accumulated sensory evidence. In two experiments with human participants, we show that neither prediction holds. A simple alternative model is developed that is consistent with the results. In this estimate-then-decide model, evidence is accumulated until estimation precision reaches a threshold value. Then, a decision is made with duration that depends on the signal-to-noise ratio achieved by the first stage.
- Subjects
SENSORY discrimination; STIMULUS &; response (Biology); DRIFT diffusion models; PSYCHOPHYSICS; REACTION time
- Publication
Journal of Neuroscience, 2016, Vol 36, Issue 44, p11259
- ISSN
0270-6474
- Publication type
Article
- DOI
10.1523/JNEUROSCI.1367-16.2016