The effects of ageing on false-belief reasoning abilities: an EEG study with older and younger adults

A critical part of our day-to-day lives is our ability to understand the mental states (beliefs, desires, knowledge) of the people we interact with, often referred to as possession of a ‘Theory of Mind’ (ToM). One of the litmus tests of ToM is understanding of false-beliefs –awareness that another individual is in possession of an incorrect belief, and would be expected to act in a manner consistent with this. Prior research with young adults has shown key differences in how true-belief versus false-belief stories are processed; however, it is not currently clear whether this differentiation continues across the lifespan. This study explored how true and false-belief situations are processed by younger (18-35 years) and older (65+ years) adults. Electroencephalography (EEG) measures were taken whilst participants listened to short stories in which a character is described as having a true or false-belief about an object’s location, before acting in a manner consistent or inconsistent with their belief-state (i.e. where they look for an object). Analysis revealed that when the character held a true-belief about an object’s location, the N400 waveform was more negative-going for belief-inconsistent versus belief-consistent actions, in both younger and older adults. However, when the character held a false-belief about an object’s location, older adults showed the opposite pattern, with more negative-going waveforms for belief-consistent than belief-inconsistent actions, which was not the case for the younger adults. Results suggest potential differences in the processes underlying belief-reasoning across the lifespan.