CSTM_TX

dCSTM_TX

pCSTM_TX

rCSTM_TX

Density (PDF), distribution function (CDF), and random sampler for a custom time- and evidence-dependent (CSTM_TX) drift diffusion model.

Calculate the probability density functions (PDFs) for two threshold evidence
accumulation models (EAMs). These are defined using the following Stochastic
Differential Equation (SDE), dx(t) = v(x(t),t)*dt+D(x(t),t)*dW, where x(t) is
the accumulated evidence at time t, v(x(t),t) is the drift rate, D(x(t),t) is
the noise scale, and W is the standard Wiener process. The boundary conditions
of this process are the upper and lower decision thresholds, represented by b_u(t)
and b_l(t), respectively. Upper threshold b_u(t) > 0, while lower threshold b_l(t) < 0.
The initial condition of this process x(0) = z where b_l(t) < z < b_u(t). We
represent this as the relative start point w = z/(b_u(0)-b_l(0)), defined as
a ratio of the initial threshold location. This package generates the PDF using
the same approach as the 'python' package it is based upon, 'PyBEAM' by Murrow and Holmes
(2023) <doi:10.3758/s13428-023-02162-w>. First, it converts the SDE model into the
forwards Fokker-Planck equation dp(x,t)/dt = d(v(x,t)*p(x,t))/dt-0.5*d^2(D(x,t)^2*p(x,t))/dx^2,
then solves this equation using the Crank-Nicolson method to determine p(x,t). Finally,
it calculates the flux at the decision thresholds, f_i(t) = 0.5*d(D(x,t)^2*p(x,t))/dx
evaluated at x = b_i(t), where i is the relevant decision threshold, either upper (i = u)
or lower (i = l). The flux at each thresholds f_i(t) is the PDF for each threshold,
specifically its PDF. We discuss further details of this approach in this package
and 'PyBEAM' publications. Additionally, one can calculate the cumulative distribution
functions of and sampling from the EAMs.

Raphael Hartmann

ream

Density, Distribution, and Sampling Functions for Evidence
Accumulation Models

Matthew Murrow

CSTM_TX function

<dl><dt>rt</dt>
<dd>vector of response times</dd>
<dt>resp</dt>
<dd>vector of responses ("upper" and "lower")</dd>
<dt>phi</dt>
<dd>parameter vector in your specified order</dd>
<dt>x_res</dt>
<dd>spatial/evidence resolution</dd>
<dt>t_res</dt>
<dd>time resolution</dd>
<dt>n</dt>
<dd>number of samples</dd>
<dt>dt</dt>
<dd>step size of time. We recommend 0.00001 (1e-5)</dd></dl>

Arguments

Raphael Hartmann &amp; Matthew Murrow

Author

Custom Time- and Evidence-Dependent Drift Diffusion Model — CSTM_TX

<dl>

<dt>rt</dt>
<dd>vector of response times</dd>


<dt>resp</dt>
<dd>vector of responses ("upper" and "lower")</dd>


<dt>phi</dt>
<dd>parameter vector in your specified order</dd>


<dt>x_res</dt>
<dd>spatial/evidence resolution</dd>


<dt>t_res</dt>
<dd>time resolution</dd>


<dt>n</dt>
<dd>number of samples</dd>


<dt>dt</dt>
<dd>step size of time. We recommend 0.00001 (1e-5)</dd>

</dl>

CSTM_TX: Custom Time- and Evidence-Dependent Drift Diffusion Model

Description

Usage

Value

Arguments

Author

References