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Abstract:
ObjecPve: The arbitraPon between a Pmely decision and extended informaPon gathering involves a nontrivial
speed-accuracy tradeoff (Henmon, 1911; MarPn and Müller, 1899). SequenPal informaPon
gathering tasks are commonly used to invesPgate this arbitraPon; that it is impaired in psychiatric
disorders such as schizophrenia or obsessive-compulsive disorder (Hauser et al., 2017; Moutoussis et al.,
2011), suggests that its neurocogniPve mechanisms merit beSer understanding. Methods: We
invesPgated the role of dopamine and noradrenaline in a sequenPal informaPon gathering task
("informaPon sampling task" [IST]; Hauser et al., 2017) using a double-blind, placebo-controlled,
between-subjects drug study. Three groups of 20 subjects each received either a noradrenaline betareceptor
antagonist (40mg propranolol), a dopamine D2/3 receptor blocker (400mg amisulpride) or a
placebo. Subjects were allowed to gather as much informaPon as they wanted before making a decision
about which of two colours was more plenPful in a set of 25 hidden cards. We used a recently developed
Bayesian computaPonal model (Hauser et al., 2017) to invesPgate the cogniPve processes driving this
informaPon gathering behaviour. Results: Noradrenaline blockade led to reduced informaPon gathering,
whether sampling was costly or cost-free. No effect was observed for dopamine blockade.
ComputaPonal modelling suggested that subjects exhibited a subjecPve urgency to make a decision as
sampling progressed; i.e., subjects applied progressively more liberal criteria or a collapsing bound on
the evidence. This urgency increased in a non-linear manner and its onset varied across parPcipants. We
found that the noradrenaline group expressed a significantly earlier urgency onset than the placebo
group. Conclusions: Our results show that noradrenaline plays a criPcal role in informaPon gathering and
that blocking noradrenaline leads to more impulsive responses due to an increased urgency to decide.
Our findings thus provide important insight into the neurocogniPve mechanisms of informaPon
gathering, which may also help beSer understand psychiatric disorders that show impairments in informaPon gathering.
