Table 2.

One-choice and two-choice diffusion model parameter estimates for experiment 1

					Easy	Medium	Difficult	Easy	Medium	Difficult
Task	Value	a	Ter	st	v1	v2	v3	η1	η2	η3	χ2
Simple (one-choice)	Mean	0.136	253	136	0.777	0.567	0.321	0.262	0.209	0.153	47.9
	SD	0.017	34	37	0.191	0.122	0.068	0.076	0.049	0.047	9.6
Two-choice	Mean	0.155	466	160	0.352	0.250	0.118	0.150			64.3
	SD	0.031	59	68	0.105	0.086	0.047	0.072			22.4

Note: χ², df = 50 for the simple RT task (critical value 71) and, df = 56 for the two-choice task (critical value 79). Variability in starting point (s_z) across trials in the two-choice task has estimated range 0.054 with SD 0.035. a, boundary setting; T_er, nondecision component of response time; η, SD in drift across trials; s_t, range of the distribution of nondecision times, and v₁, v₂, and v₃ are drift rates.