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Attention as a source of overall value effects in diffusion models

Blair Shevlin
Icahn School Of Medicine at Mount Sinai ~ Psychiatry
Prof. Ian Krajbich
University of California, LA ~ Psychology

Research has demonstrated that value-based decisions depend not only on the relative difference between options, but also on their overall value. In particular, response times tend to decrease as the overall value of the alternatives increase. Standard sequential sampling models such as the diffusion model can account for this fact by assuming that decision thresholds or noise vary with overall value. Alternatively, attention-based models that incorporate eye-tracking data produce this overall value effect as a direct consequence of the multiplicative relationship between attention and value. Using a non-attentional diffusion model fit to data simulated with an attention-based model, we find that parameters related to decision thresholds or noise vary as a function of overall value, even though these were not features of the data-generating process. We find additional evidence for misidentified parameters in a similar analysis using two empirical datasets. In both datasets, models that incorporated attention-based evidence accumulation provided superiors fits to the empirical data and led to different conclusions about value-based boundaries. Our results indicate that neglecting attentional effects can lead to mistaken conclusions about which decision parameters (e.g., noise or thresholds) are sensitive to overall value.



diffusion model
overall value effect
response time models


Cognitive Modeling
Decision Making
Reaction Times
Model Analysis and Comparison
Accumulator/Diffusion models

Thank you for this talk! I have a question about the simulations of aDDM. Is the within trial drift variability parameter S a separable parameter from the diffusion coefficient T, such that the instantaneous change in evidence E within a trial is described by the Wiener process dE/dt ~ N(Drift, T^2) ? I ask because we had previously found a...

Dr. Michael D. Nunez 2 comments

thanks for the nice talk! you mention that the attention effect is mediated by gaze, I would be surprised in the OV effect disappeared if participants were instructed to keep their eyes fixated. Luckily, shifting covert attention sequentially across options would also be expected to boost visual processing. The idea that attention would randoml...

Dr. Aline Bompas 1 comment
Cite this as:

Shevlin, B., & Krajbich, I. (2020, July). Attention as a source of overall value effects in diffusion models. Paper presented at Virtual MathPsych/ICCM 2020. Via