Non-monotonic Temporal-Weighting Indicates a Dynamically Modulated Evidence-Integration Mechanism

PLoS Comput Biol. 2016 Feb 11;12(2):e1004667. doi: 10.1371/journal.pcbi.1004667. eCollection 2016 Feb.

Abstract

Perceptual decisions are thought to be mediated by a mechanism of sequential sampling and integration of noisy evidence whose temporal weighting profile affects the decision quality. To examine temporal weighting, participants were presented with two brightness-fluctuating disks for 1, 2 or 3 seconds and were requested to choose the overall brighter disk at the end of each trial. By employing a signal-perturbation method, which deploys across trials a set of systematically controlled temporal dispersions of the same overall signal, we were able to quantify the participants' temporal weighting profile. Results indicate that, for intervals of 1 or 2 sec, participants exhibit a primacy-bias. However, for longer stimuli (3-sec) the temporal weighting profile is non-monotonic, with concurrent primacy and recency, which is inconsistent with the predictions of previously suggested computational models of perceptual decision-making (drift-diffusion and Ornstein-Uhlenbeck processes). We propose a novel, dynamic variant of the leaky-competing accumulator model as a potential account for this finding, and we discuss potential neural mechanisms.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Choice Behavior / physiology*
  • Computational Biology
  • Decision Making / physiology*
  • Humans
  • Models, Biological*
  • Task Performance and Analysis

Grant support

This research was supported by the ICORE Program of the Planning and Budgeting Committee and The Israel Science Foundation (grant no. 51/11 and grant no. 743/12 to MU). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.