“Choosing the lesser of two evils”: The neural mechanisms of outcome evaluation in mixed intertemporal choices

Mixed intertemporal choice involves health, economic, and social domains, but the neural mechanisms underlying the evaluation of mixed intertemporal choices have not been fully elucidated. This study employed event-related potential (ERP) technique and recruited 46 college students to explore the neural mechanisms underlying the evaluation of mixed intertemporal choices (i.e.,smaller and sooner loss, larger and later gain (SSL-LLG) and smaller and sooner gain, larger and later loss (SSG-LLS)) through two experimental conditions: separate evaluation conditions (n = 24) and joint evaluation conditions (n = 22). The results showed that negative loss feedbacks elicited a more negative FRN amplitudes than positive gain feedbacks, and the P300 amplitudes triggered by negative loss feedbacks was significantly lower than that induced by positive gain feedbacks (Experiment 1). The FRN amplitude for SSL-LLG choices was more negative than that for SSG-LLS choices, while P300 amplitude differences between these two conditions were not significant.(Experiment 2). In summary, loss choices elicited stronger loss perception and reduced cognitive resource allocation; emotional experience and cognitive resource engagement in outcome evaluation of mixed gain-loss options were similar to those of pure loss intertemporal choices. Loss perception was greater in SSL-LLG than SSG-LLS conditions, eliciting stronger negative emotions, though cognitive resource use did not differ significantly between this two choices. This explains individuals’ preference for SSG-LLS choices as a strategy of “choosing the lesser of two evils”. Therefore, understanding the neural mechanisms of loss perception holds practical significance for encouraging more rational decision-making behavior.