September 2021
Volume 21, Issue 9
Open Access
Vision Sciences Society Annual Meeting Abstract  |   September 2021
Estimating decision time in perceptual decision making
Author Affiliations
  • Ying Lin
    University of Rochester
    Center for Visual Science
  • Duje Tadin
    University of Rochester
    Center for Visual Science
Journal of Vision September 2021, Vol.21, 2694. doi:
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      Ying Lin, Duje Tadin; Estimating decision time in perceptual decision making. Journal of Vision 2021;21(9):2694.

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      © ARVO (1962-2015); The Authors (2016-present)

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Decision-making research almost exclusively relies on reaction times (RT) to estimate decision time. RTs, however, also capture processes not involved in determining decisions (perceptual encoding and motor planning) and necessitate the use of models such as the drift-diffusion model (DDM; Ratcliff & McKoon, 2008) to estimate decision time. Here, we report experiments that support a more direct measure of perceptual decision time: duration threshold, defined as the shortest stimulus presentation duration sufficient to accurately make a perceptual decision. First, we conducted both RT and duration threshold experiments with a widely used task in the perceptual decision-making literature, the random dot motion task (Newsome & Pare, 1988; Roitman & Shadlen, 2002; Hawkins et al., 2015). Twelve participants completed both experiments for six coherence levels (10%-100%). We found that the pattern of duration thresholds over motion coherences closely followed the pattern of DDM-derived decision times and coherence-dependent changes in DDM drift rate. Second, we tested the generalizability of the duration threshold approach using a static orientation discrimination task (N=12) with 8 contrast levels (2.1%-100%). We found that contrast affected performance in a different way than coherence. However, once again, duration thresholds demonstrated a similar pattern as DDM-derived decision times. Lastly, we examined our overall hypothesis in the context of a more complex phenomenon: surround suppression. We used a motion direction discrimination task consisting of two contrasts and three sizes. Participants (N=8) showed elevated duration thresholds for large, high contrast stimuli, replicating previous results of contrast-dependent surround suppression (Tadin et al., 2003). Notably, DDM-derived decision times and not the overall RTs exhibited this contrast-dependent surround suppression. In summary, we show a close correspondence between DDM-derived decision times and duration thresholds in three separate experiments. Evidently, duration thresholds can be used as a direct estimate of perceptual decision time.


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