The urgency-gating model, developed by Cisek, Puskas, and El-Murr (2009), proposes that decisions are driven not by accumulated evidence but by the product of momentary evidence and a time-increasing urgency signal. This architecture produces behavior equivalent to collapsing decision boundaries — the effective threshold for responding decreases over time — and naturally explains why decision makers become less selective as time pressure increases.
Model Formulation
u(t) = urgency signal (increasing with time)
e(t) = momentary evidence (not accumulated)
Respond when y(t) exceeds threshold
Collapsing Bounds
Traditional accumulator models assume fixed decision boundaries. The urgency-gating model effectively implements collapsing bounds: as the urgency signal grows, weaker evidence becomes sufficient to trigger a response. This produces faster but less accurate decisions under time pressure without explicitly changing the threshold. The model accounts for findings that are difficult for fixed-boundary models, including speed-accuracy tradeoff curves that do not asymptote and neural evidence showing urgency-like signals in premotor and parietal cortex that ramp up independently of stimulus information.