A Movement-Independent Signature of Urgency during Human Perceptual Decision-Making.

How does the brain adjust its decision processes to ensure timely decision completion? Computational modeling and electrophysiological investigations have pointed to dynamic "urgency" processes that serve to progressively reduce the quantity of evidence required to reach choice commitment as time elapses. In humans, such urgency dynamics have been observed exclusively in neural signals that accumulate evidence for a specific motor plan. Across three complementary experiments in humans (male and female), we characterize an electrophysiological signal that traces dynamic urgency and exhibits unique properties not observed in effector-selective signals. Firstly, it provides a representation of urgency alone, growing only as a function of time and not evidence strength. Secondly, when choice reports must be withheld until a response cue, this signal peaks and decays long before response execution, mirroring the early termination dynamics of a motor-independent evidence accumulation signal. These properties suggest that the brain may use urgency signals not only to expedite motor planning but also to hasten cognitive deliberation. These data demonstrate that urgency processes operate in a variety of perceptual choice scenarios and that they can be monitored in a model-independent manner via noninvasive brain signals.