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. 2021 Mar 13;1(1):5–15. doi: 10.1016/j.bpsgos.2021.02.001

Figure 2.

Figure 2

Simulated data that illustrate the behavioral manifestations of differences in efficiency of evidence accumulation (EEA). Response time (RT) data from 10,000 trials were simulated with the diffusion decision model implemented in the R package rtdists (149) while varying drift rate (v = 2, 1, 0.5) and holding other diffusion decision model parameters constant (a = 1, z = 0.5, Ter = 0.300). Blue histograms represent simulated correct RTs, while red histograms represent simulated error RTs. As EEA (v) decreases, accuracy rates are reduced and both the mean and standard deviation of RT increase. However, analysis of RTs with the ex-Gaussian distribution, a statistical model that allows Gaussian and exponential components of RT distributions to be indexed separately, reveals that the mean (μ) and Gaussian variability (σ) stay relatively constant, while exponential RT variability (τ; positive skew) substantially increases at lower levels of EEA. Therefore, as demonstrated in previous large-scale simulation studies (91), EEA primarily affects RT distributions’ level of exponential RT variability, with larger τ estimates (i.e., greater levels of positive skew) providing a behavioral hallmark for reduced EEA.