The effect of time pressure on decision making
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1
University of Washington, Department of Physiology and Biophysics, NPRC, United States
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2
University of Washington, HHMI, Department of Physiology and Biophysics, NPRC, United States
The accuracy of many decisions can be improved by acquiring additional information, albeit at the cost of time. When a human or monkey is asked to decide the direction of motion in a noisy display, accuracy improves with viewing duration in a manner that is consistent with perfect integration of independent samples of evidence - at least up to a point. One idea is that decisions end when the accumulated evidence reaches a threshold level, or bound. This idea explains the tradeoff between speed and accuracy of many decisions. However, it does not explain how a decision maker would incorporate a time pressure (or cost) that changes dynamically. We hypothesized that, under time pressure, subjects adjust their criterion for terminating decisions in a time-dependent manner. To test this we manipulated the cost of elapsed time during a simple perceptual decision. Human subjects discriminated the direction of dynamic random dot motion in a choice-reaction time paradigm. They indicated their decisions by making an eye movement whenever ready. Two directions and 6 motion strengths were randomly interleaved. Subjects gained and lost points for correct and incorrect choices, respectively. After each trial they received feedback about their total score and their average rate (points per minute). After 16-20 sessions, we introduced a manipulation that was unknown to the subject: a fraction of trials were terminated prematurely by the experimenter, as if the computer had sensed a fixation error. The manipulation caused subjects to make faster, less accurate decisions. A drift-diffusion model with stationary bounds explained the choices and mean reaction time (RT) for correct choices. To explain the RT on incorrect choices and the shape of the RT distributions, we incorporated a time-dependent stopping rule - that is, collapsing bounds. The rate of this collapse was significantly faster when subjects experienced the premature terminations of trials. These results underscore a flexible termination strategy for decisions. This flexibility is influenced by the subjective cost of decision time.
Acknowledgements: We thank R. Kiani for software and advice. This work was supported by HHMI, EY011378, DA022780, and RR000166. S. Kira was supported by a Nakajima Foundation Predoctoral Fellowship.
Conference:
Computational and Systems Neuroscience 2010, Salt Lake City, UT, United States, 25 Feb - 2 Mar, 2010.
Presentation Type:
Poster Presentation
Topic:
Poster session I
Citation:
Kira
S and
Shadlen
MN
(2010). The effect of time pressure on decision making.
Front. Neurosci.
Conference Abstract:
Computational and Systems Neuroscience 2010.
doi: 10.3389/conf.fnins.2010.03.00029
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Received:
18 Feb 2010;
Published Online:
18 Feb 2010.
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Correspondence:
Shinichiro Kira, University of Washington, Department of Physiology and Biophysics, NPRC, Seattle, United States, shinkira@u.washington.edu