Contextual Valence Influences The Neural Dynamics Of Time And Magnitude Representation During Feedback Evaluation

Contextual valence is an important dimension during value-based decision making.Previous research has found behavioral and neural mechanism asymmetries between gain and loss contexts,as evidenced by the stronger psychological impact of losses.All other things being equal,individuals are more willing to overcome probability costs and effort costs to avoid losses than to acquire the equivalent rewards.This gain-loss asymmetry has received extensive attention and research in the processing of two important reward dimensions,time and magnitude,in different contexts.The subjective value of the outcome is devalued over the delay time,and this delay discount is stronger in reward contexts than in loss contexts,known as the sign effect.Since previous studies have rarely investigated information processing in loss contexts,it is of great scientific and practical importance to compare the cognitive mechanisms and neural basis of the temporal discounting phenomenon in gain and loss contexts under the same research framework.The present study investigates the effect of contextual valence on the neural dynamics of two information dimensions,magnitude and time,during feedback evaluation by means of an event-related potentiation technique that has high temporal resolution.Experiment 1 recruited 42 enrolled university students and recorded their EEG data by completing a modified gate selection task simultaneously.The participants’ EEG data was analyzed for the representation of temporal and magnitude information during the feedback phase of the experiment.It was revealed that in the gain context,both the reward positivity(RewP)and the P3 component encoded temporal and magnitude information together,showing smaller amplitudes for delayed rewards and larger amplitudes for large magnitude rewards.While the loss context was found to process temporal information first on the RewP and P3 components,the amplitudes of delayed loss were significantly smaller than immediate loss,and then the magnitude information was processed on the LPP component.These findings provide preliminary support for the separation of information processing patterns under contextual valence.Experiment Ⅱ,based on Experiment Ⅰ,changed the temporal and magnitude information into parametric variation,still recording their EEG activity simultaneously during the completion of the gate selection task.Experiment Ⅱ results revealed that both contextual valences showed a preference for short delay outcomes at reward positivity(RewP),with amplitude decreasing as delay time increased.The P3 component found significant three-dimensional interactions between contextual validity,delay time,and magnitude,specifically a temporal discounting phenomenon in which the salience of magnitude rewards diminished with increasing delay time in the reward context.In contrast,no relevant effect was found for P3 in the loss context.The LPP component encodes both temporal and magnitude information in the reward context,whereas the loss context processes only magnitude information.Together,these results validate that there are significant differences in the neural mechanisms of processing temporal and magnitude information in different contexts.The results indicate that the reward context adopts a parallel processing mode,integrating the encoding and processing of both temporal and magnitude information,while the loss context is in a serial processing mode,first encoding temporal information followed by the processing of magnitude information.The present study used a series of experiments to explore the information processing patterns in different contexts,which not only helps to understand the asymmetry of the loss and gain contexts,but also helps us to better understand the internal mechanisms of related psychiatric disorders,including depression,schizophrenia,and substance abuse.