Abstract
Decisions are often made by accumulating ambiguous evidence over time. The brain’s arousal systems are activated during such decisions. In previous work in humans, we showed that evoked responses of arousal centers during decisions are reported by rapid dilations of the pupil, and predict a suppression of biases in the accumulation of decision-relevant evidence (de Gee et al. 2017). Here, we show that this arousal-related suppression in decision bias acts on both conservative and liberal biases, and generalizes across species (humans / mice), sensory systems (visual / auditory), and domains of decision-making (perceptual / memory-based). In challenging sound-detection tasks, the impact of spontaneous or experimentally induced choice biases was reduced under high arousal. Similar bias suppression occurred when evidence was drawn from memory. All these behavioral effects were explained by reduced evidence accumulation biases. Our results pinpoint a general principle of the interplay between phasic arousal and decision-making.
Footnotes
↵# lead contact
We rewrote the manuscript to consistently interpret the pupil response in terms of phasic arousal. We also conducted one new experiment in which we systematically manipulated signal probability, and found that, within the same subjects, phasic arousal flexibly reduces both conservative and liberal accumulation biases in a context-dependent manner. Finally, we replicated the pupil-predicted suppression of biases of both signs in a large sample of human subjects performing a memory task; bringing in yet another mode of decision-making (memory-based decisions) further generalized our claim.
