Evidence and Urgency Related EEG Signals during Dynamic Decision-Making in Humans

Abstract

A successful class of models link decision-making to brain signals by assuming that evidence accumulates to a decision threshold. These evidence accumulation models have identified neuronal activity that appears to reflect sensory evidence and decision variables that drive behavior. More recently, an additional evidence-independent and time-variant signal, called urgency, has been hypothesized to accelerate decisions in the face of insufficient evidence. However, most decision-making paradigms tested with fMRI or EEG in humans have not been designed to disentangle evidence accumulation from urgency.Here we use a face-morphing decision-making task in combination with EEG and a hierarchical Bayesian model to identify neural signals related to sensory and decision variables, and to test the urgency-gating model. Forty females and 34 males took part (mean age, 23.4 years). We find that an evoked potential time locked to the decision, the centroparietal positivity, reflects the decision variable from the computational model. We further show that the unfolding of this signal throughout the decision process best reflects the product of sensory evidence and an evidence-independent urgency signal. Urgency varied across subjects, suggesting that it may represent an individual trait. Our results show that it is possible to use EEG to distinguish neural signals related to sensory evidence accumulation, decision variables, and urgency. These mechanisms expose principles of cognitive function in general and may have applications to the study of pathologic decision-making such as in impulse control and addictive disorders.

As within, so without, as above, so below: Common mechanisms can support between- and within-trial category learning dynamics.

“…Using variants of AARM that instantiated different modes of simplicity bias, Galdo et al (2021) provided evidence that humans tend toward low-dimensional representations as they learn. One interpretation of these findings is that while humans strive to achieve high accuracy in a task setting, they concurrently seek to reduce time and resource expenditure on individual trials (Boureau et al, 2015; Cisek et al, 2009; Thura et al, 2012; Yau et al, 2021).…”

Pupillary dynamics reflect the impact of temporal expectation on detection strategy

“… 16 , 17 Like the conceptual framework of SAT, temporal expectation has been implemented through an urgency signal which biases the decision variable toward earlier responses. 11 , 12 , 18 , 19 , 20 Intriguingly, recent experimental evidence interprets urgency as a multiplicative factor which amplifies sensory evidence, leading to faster decisions 21 , 22 as well as impacting evidence-independent motor preparation. 12 Overall, how experimental manipulations of subjects’ temporal expectation impact internal urgency is still a matter of debate.…”

Temporal dynamics of decision making: A synthesis of computational and neurophysiological approaches

“…Moreover, a recent study that tested various parameters in a prior-cued perceptual discrimination task found strong support for an urgency signal across all tested combinations of task demands and evidence (Kelly et al, 2020). Other new work further corroborates the urgency gating model, showing that the buildup of evidence accumulation signals in parietal cortex correlates more strongly with the temporal profile of evidence accumulation predicted by the urgency gating model than by a constant evidence accumulation model (Yau et al, 2021). Thus, rather than decision makers simply adjusting the physiological value of the response-triggering threshold to allow for speeded responding, a number of other adjustments might occur.…”