Multiphasic Value Biases in Fast-Paced Decisions

Includes raw data, analysis and modelling code from Corbett, Martinez-Rodriguez, Judd, O'Connell & Kelly (2023), Multiphasic Value Biases in Fast Paced Decisions, Elife 12, e67711. 

Perceptual decisions are biased toward higher-value options when overall  gains can be improved. When stimuli demand immediate reactions, the  neurophysiological decision process dynamically evolves through distinct  phases of growing anticipation, detection and discrimination, but how  value biases are exerted through these phases remains unknown. Here, by  parsing motor preparation dynamics in human electrophysiology, we  uncovered a multiphasic pattern of countervailing biases operating in  speeded decisions. Anticipatory preparation of higher-value actions  began earlier, conferring a “starting point”-advantage at stimulus  onset, but the delayed preparation of lower-value actions was steeper,  conferring a value-opposed buildup rate bias. This, in turn, was  countered by a transient deflection toward the higher value action  evoked by stimulus detection. A neurally-constrained process model  featuring anticipatory urgency, biased detection, and accumulation of  growing stimulus-discriminating evidence, successfully captured both  behavior and motor preparation dynamics. Thus, an intricate interplay of  distinct biasing mechanisms serves to prioritise time-constrained  perceptual decisions.