Perceptual decision making in less than 30 milliseconds

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In perceptual discrimination tasks, a subject's response time is determined by both sensory and motor processes. Measuring the time consumed by the perceptual evaluation step alone is therefore complicated by factors such as motor preparation, task difficulty and speed-accuracy tradeoffs. Here we present a task design that minimizes these confounding factors and allows us to track a subject's perceptual performance with unprecedented temporal resolution. We find that monkeys can make accurate color discriminations in less than 30 ms. Furthermore, our simple task design provides a tool for elucidating how neuronal activity relates to sensory as opposed to motor processing, as demonstrated with neural data from cortical oculomotor neurons. In these cells, perceptual information acts by accelerating and decelerating the ongoing motor plans associated with correct and incorrect choices, as predicted by a race-to-threshold model, and the time course of these neural events parallels the time course of the subject's choice accuracy.

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Figure 1: Sequence of events in the compelled-saccade task.
Figure 2: Oculomotor execution during the compelled-saccade task.
Figure 3: Behavioral and model performance in the compelled-saccade task.
Figure 4: Five trials of the race-to-threshold model.
Figure 5: Behavioral and model performance in the motor-bias experiment.
Figure 6: Oculomotor activity during the compelled-saccade task.
Figure 7: Sensory information accelerates oculomotor activity.


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Research was supported by the National Institutes of Health/National Eye Institute grant R01 EY12389 to T.R.S.

Author information

T.R.S. conceived the task, supervised all experiments and data analyses, and co-wrote the manuscript; S.S. contributed to the collection, analysis and modeling of the behavioral data; D.P.M. contributed to the design of the experiments and to the collection of behavioral data; M.G.C. contributed to the collection of behavioral data and to the collection and analysis of neural data; E.S. developed the race model, contributed to the experimental design and data analysis and co-wrote the manuscript.

Correspondence to Emilio Salinas.

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The authors declare no competing financial interests.

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Supplementary Figures 1–5 and Supplementary Notes 1–7 (PDF 220 kb)

Supplementary Movie 1 (AVI 4774 kb)

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Stanford, T., Shankar, S., Massoglia, D. et al. Perceptual decision making in less than 30 milliseconds. Nat Neurosci 13, 379–385 (2010) doi:10.1038/nn.2485

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