dDMC_grid {ream} | R Documentation |
Generate Grid for PDF of Diffusion Model of Conflict Tasks
Description
Generate a grid of response-time values and the corresponding PDF values.
For more details on the model see, for example, dDMC
.
Usage
dDMC_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) .
Coherence parameter (s ). Sets stimulus coherence. If s = 1 , coherent condition;
if s = 0 , neutral condition; if s = -1 , incoherent condition.
Automatic process amplitude (A ). Max value of automatic process.
Scale parameter (\tau ). Contributes to time automatic process. Time to max
t_{max} = (\alpha – 1)*\tau .
Shape parameter (\alpha ). Indicates the shape of the automatic process. Must
have value more than 1 (\alpha > 1 ).
Drift rate of the controlled process (\mu_c ).
Noise scale (\sigma ). Model noise scale parameter.
Decision thresholds (b ). Sets the location of each decision threshold. The
upper threshold b_u is above 0 and the lower threshold b_l is below 0 such that
b_u = -b_l = b . The threshold separation a = 2b .
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
Ulrich, R., Schröter, H., Leuthold, H., & Birngruber, T. (2015). Automatic
and controlled stimulus processing in conflict tasks: Superimposed diffusion
processes and delta functions. Cognitive psychology, 78, 148-174.
[Package
ream version 1.0-5
Index]