compute mean exit (decision) time conditional on exit point (chosen alternative) of a diffusion process

Description

Given a boundary separation, a starting point, and a drift rate, this function computes the mean exit time/exit time variance of a one dimensional diffusion process under constant drift on an interval with absorbing boundaries, conditioned on the point of exit. Used as a model of information accumulation, it is gives the mean decision time/decision time variance of responses in a speeded two-alternative forced choice (2AFC) response time task, conditional on what alternative was decided upon.

Usage

EZ2.cmrt(nu, z, a, s = 0.1)
EZ2.cvrt(nu, z, a, s = 0.1)

Arguments

Details

This model of information accumulation and decision is a simplified version of 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).

Value

EZ2.cmrt returns the mean exit/decision time(s) EZ2.cvrt returns the exit/decision time variance(s) The return value has the attribute "gradient" attached: the gradient with respect to each of the parameters.

Note

Author(s)

Raoul Grasman

References

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

See Also

EZ2-package, EZ2.mrt, EZ2.vrt

Examples

    EZ2.mrt( 0.1, 0.08, 0.12, Ter=0.25)
    EZ2.vrt( 0.1, 0.08, 0.12)