PT  - JOURNAL ARTICLE
AU  - Corbett, Elaine A.
AU  - Martinez-Rodriguez, L. Alexandra
AU  - Judd, Cian
AU  - O’Connell, Redmond G.
AU  - Kelly, Simon P.
TI  - Multiphasic value biases in fast-paced decisions
AID  - 10.1101/2021.03.08.434248
DP  - 2022 Jan 01
TA  - bioRxiv
PG  - 2021.03.08.434248
4099  - http://biorxiv.org/content/early/2022/12/02/2021.03.08.434248.short
4100  - http://biorxiv.org/content/early/2022/12/02/2021.03.08.434248.full
AB  - 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.Competing Interest StatementThe authors have declared no competing interest.