Advice-taking as a bridge between decision neuroscience and mental capacity.

A person's capacity to process advice is an important aspect of decision making in the real world. For example, in decisions about treatment, the way patients respond to the advice of family, friends and medical professionals may be used (intentionally or otherwise) as a marker of the "use or weigh" requirement of decision-making capacity. Here we explore neuroscientific research on decision-making to identify features of advice-taking that help conceptualize this requirement. We focus on studies of the neural and computational basis of decision-making in laboratory settings. These studies originally investigated simple perceptual decisions about ambiguous stimuli, but have more recently been extended to more complex "value-based" decisions involving the comparison of subjective preferences. Value-based decisions are a useful model system for capacity-related decision-making as they do not have an objectively 'correct' answer and are instead based on subjective preferences. In this context, advice-taking can be seen as a process in which new evidence for one or other option is integrated, leading to altered behaviour or choices. We use this framework to distinguish between different types of advice-taking: private compliance consists of updating one's privately held beliefs based on new evidence, whereas in the case of public compliance, people change their behaviour at a surface level without shifting their privately-held beliefs. Importantly, both types of advice-taking may lead to similar outcomes but rely on different decision processes. We suggest that understanding how multiple mechanisms drive advice-taking holds promise for targeting decision-making support and improving our understanding of the use and weigh requirement in cases of contested capacity.