The effect of uncertainty on pain decisions for self and others.

Background: Estimating others' pain is a challenging inferential process, associated with a high degree of uncertainty. While much is known about uncertainty's effect on self-regarding actions, its impact on other-regarding decisions for pain have yet to be characterized.

Aim: The present study exploited models of probabilistic decision-making to investigate how uncertainty influences the valuation and assessment of another's pain.

Materials & Methods: We engaged 63 dyads (43 strangers and 20 romantic couples) in a task where individual choices affected the pain delivered to either oneself (the agent) or the other member of the dyad. At each trial, agents were presented with cues predicting a given pain intensity with an associated probability of occurrence. Agents either chose a sure (mild decrease of pain) or risky (50% chance of avoiding pain altogether) management option, before bidding on their choice. A heat stimulation was then issued to the target (self or other). Decision-makers were then asked to rate the pain administered to the target.

Results: We found that the higher the expected pain, the more risk-averse agents became, in line with findings in value-based decision-making. Furthermore, agents gambled less on another individual's pain (especially strangers) and placed higher bids on pain relief than they did for themselves. Most critically, the uncertainty associated with expected pain dampened ratings made for strangers' pain. This contrasted with the effect on an agent's own pain, for which risk had a marginal hyperalgesic effect.

Discussion & Conclusion: Overall, our results suggested that risk selectively affects decision-making on a stranger's suffering, both at the level of assessment and treatment selection, by (1) leading to underestimation, (2) privileging sure options and (3) altruistically allocating more money to insure the treatment's success.

Significance: Uncertainty biases decision-making but it is unclear if it affects choice behavior on pain for others. In examining this question, we found individuals were generally risk-seeking when faced with looming pain, but more so for self; and assigned higher monetary values and subjective ratings on another's pain. However, uncertainty dampened agents' assessment of a stranger's pain, suggesting latent variables may contradict overt altruism. This bias may underlie pain underestimation in clinical settings.