dRTM_grid: Generate Grid for PDF of the Rational Threshold Model

In ream: Density, Distribution, and Sampling Functions for Evidence Accumulation Models

Generate Grid for PDF of the Rational Threshold Model

Description

Generate a grid of response-time values and the corresponding PDF values. For more details on the model see, for example, dRTM.

Usage

dRTM_grid(rt_max = 10, phi, x_res = "default", t_res = "default")

Arguments

rt_max	maximal response time <- max(rt)
phi	parameter vector in the following order: Non-decision time (t_{nd}). Time for non-decision processes such as stimulus encoding and response execution. Total decision time t is the sum of the decision and non-decision times. Relative start (w). Sets the start point of accumulation as a ratio of the two decision thresholds. Related to the absolute start z point via equation z = b_l + w*(b_u - b_l). Stimulus strength (\mu). Strength of the stimulus and used to set the drift rate. For changing threshold models v(x,t) = \mu. Noise scale (\sigma). Model noise scale parameter. Initial decision threshold location (b_0). Sets the location of each decision threshold at time t = 0. Amount of decision threshold collapse (\kappa). Semi-saturation constant (t_{0.5}). The semi-saturation constant is the value of time at which the boundaries have collapsed by half \kappa. Contamination (g). Sets the strength of the contamination process. Contamination process is a uniform distribution f_c(t) where f_c(t) = 1/(g_u-g_l) if g_l <= t <= g_u and f_c(t) = 0 if t < g_l or t > g_u. It is combined with PDF f_i(t) to give the final combined distribution f_{i,c}(t) = g*f_c(t) + (1-g)*f_i(t), which is then output by the program. If g = 0, it just outputs f_i(t). Lower bound of contamination distribution (g_l). See parameter g. Upper bound of contamination distribution (g_u). See parameter g.
x_res	spatial/evidence resolution
t_res	time resolution

Value

list of RTs and corresponding defective PDFs at lower and upper threshold

Author(s)

Raphael Hartmann & Matthew Murrow

References

Churchland, A. K., Kiani, R., & Shadlen, M. N. (2008). Decision-making with multiple alternatives. Nature Neuroscience, 11(6), 693-702.

Hanks, T. D., Mazurek, M. E., Kiani, R., Hopp, E., & Shadlen, M. N. (2011). Elapsed Decision Time Affects the Weighting of Prior Probability in a Perceptual Decision Task. The Journal of Neuroscience, 31(17), 6339-6352.

Voskuilen, C., Ratcliff, R., & Smith, P. L. (2016). Comparing fixed and collapsing boundary versions of the diffusion model. Journal of Mathematical Psychology, 73, 59-79.

ream documentation built on Oct. 7, 2024, 1:20 a.m.