Lateralized readiness potential interpret the effects of task difficulty on decision making

It is assumed that the network of cortical brain area associated with task difficulty may dynamically allocate resources for difficult decisions. As a result, it could play an indispensable role during the process of decision making. Recently, the lateralized readiness potential (LRP) is reinterpreted as a new way to study the evidence accumulation process during decision making. Therefore, we use LRP to investigate the effects of task difficulty on decision making. A motion detection experiment with three difficulty levels was conducted by 11 subjects. Both the EEG data and behavior data were recorded. The results show that the LRP was much more likely to appear before subjects make a response for a more difficult task. In addition, the reaction time was longer for a more difficult task. The drift diffusion model (DDM) fitting result also revealed that there had an apparently lower drift rate for the more difficult task (r=-0.463, p=0.01). These results suggest that the task difficulty would affect the quality of accumulated evidence and increase the motor preparation time, which leads to an increased decision time.