Figure 2.

Various forms of dynamic diffusion models. The Weibull cumulative distribution function can generate decision boundaries that collapse at early (left) or late (middle right) stages of processing or gradually throughout processing (middle left). Orange lines indicate strong (left) and complete (middle left, middle right) collapse of the upper and lower boundaries, which imposes a hard deadline on processing. Blue lines represent a milder form of collapsing boundary that do not meet at the midpoint $\left(\frac{1}{2}a\right)$. Right, Two illustrative urgency signal paths, which are applied as a gain (i.e., multiplicative) function on drift rates according to Equation 2. The orange and blue paths show rapid and delayed urgency signals, respectively, which are functionally similar to early and late collapsing boundaries.