. Author manuscript; available in PMC: 2016 Apr 27.

Published in final edited form as: Decision (Wash D C ). 2015 Apr 27;2015:10.1037/dec0000030. doi: 10.1037/dec0000030

Table 1. Mean Parameter Values and SD's Across Subjects for the Numerosity Discrimination Experiment.

	Trial group	a	T_er	η	s_z	p₀	s_t	v_E	v_D	χ²
Mean	1-80	0.126	0.409	0.171	0.050	0.010	0.161	0.321	0.106	25.1
	81-160	0.114	0.411	0.157	0.051	0.006	0.158	0.401	0.128	22.2
	161-240	0.118	0.400	0.138	0.051	0.009	0.172	0.383	0.127	24.5
	1-160	0.119	0.402	0.162	0.050	0.007	0.161	0.314	0.100	29.6
	161-320	0.114	0.398	0.145	0.051	0.009	0.171	0.340	0.115	33.0
	1-320	0.118	0.395	0.155	0.053	0.008	0.182	0.317	0.114	34.1
	321-640	0.114	0.382	0.145	0.063	0.008	0.174	0.324	0.108	34.6
	1-1200	0.112	0.374	0.126	0.064	0.007	0.180	0.282	0.107	50.4
SD	1-80	0.032	0.058	0.076	0.036	0.023	0.087	0.113	0.058	10.5
	81-160	0.036	0.052	0.073	0.037	0.015	0.091	0.147	0.076	10.6
	161-240	0.032	0.043	0.070	0.043	0.018	0.080	0.150	0.081	11.4
	1-160	0.026	0.047	0.075	0.036	0.019	0.078	0.107	0.039	11.0
	161-320	0.031	0.042	0.078	0.034	0.021	0.076	0.126	0.052	15.0
	1-320	0.027	0.039	0.067	0.031	0.018	0.064	0.093	0.038	13.1
	321-640	0.029	0.041	0.061	0.027	0.015	0.058	0.104	0.035	12.0
	1-1200	0.023	0.035	0.047	0.021	0.011	0.049	0.076	0.033	20.7
Mean	Simulation Parameters	0.11	0.375	0.13	0.06		0.16	0.30	0.10
SD	Simulation Parameters	0.03	0.05	0.08	0.01		0.10	0.10	0.05
Mean	Hierarchical simulation parameters: two subject groups	0.20	0.53	0.13	0.06		0.16	0.10	0.00
SD	Hierarchical simulation parameters: two subject groups	0.02	0.03	0.08	0.01		0.10	0.05	0.025

Note. a=boundary separation, z=starting point, T_er=nondecision component of response time, η =standard deviation in drift across trials, s_z=range of the distribution of starting point (z), s_t = range of the distribution of nondecision times, v_E and v_D are the drift rates for the easy and difficult conditions respectively, and χ² is the chi-square goodness of fit measure. For the data, the number of degrees of freedom for the fits to data was 30 and the critical value of chi-square at the .05 level was 43.8. In the simulations, the drift rates were correlated. The same random number was used to generate both drift rates with half the value added to the lower drift rate. The following were lower limits on parameter values: a, 0.07; η, 0.02; T_er, 0.25; s_t, 0.04, and an upper limit on s_z of 0.9a. Separate sets of simulations were conducted with p_o 0 or 0.04.