| EZ2.pe {EZ2} | R Documentation |
Computes the probability of exit through the lower bound of a univariate diffusion process with constant drift on an interval with absorbing boundaries. Used as a model of information accumulation, it is gives the probability of an error response in a speeded two-alternative forced choice (2AFC) response time task.
EZ2.pe(nu, z, a, s = 0.1)
nu |
Drift rate. |
z |
Starting point. |
a |
Boundary separation |
s |
Scaling parameter (Ratcliff's convention is s = 0.1, the default) |
This process as a model of information accumulation and decision is Ratcliff's diffusion model (1978). It can be used e.g., to compute the mean response times of the correct responses in a lexical decision time, given the drift rate, the bias (start point), and criterion (boundary separation).
EZ2.pe returns the exit probability through lower end of the interval (0,a)
The return value has the attribute "gradient" attached: the gradient with respect to each of the parameters.
Raoul Grasman
Ratcliff. Theory of Memory Retrieval. Psychological review (1978) vol. 85 (2) pp. 59-108
Grasman et al. EZ2: An extension of teh EZ-diffusion model for Response Time and Accuracy. Journal of Mathematical Psychology (2007) submitted
EZ2-package, EZ2.cmrt, EZ2.cvrt, EZ2.mrt, EZ2.vrt
EZ2.pe(.1, .08, .12)