The Dissociable Effects of Induced Positive and Negative Moods on Cognitive Flexibility

This study investigates how different valences of induced moods modulate cognitive flexibility in a task-switching paradigm. Forty-eight participants aged 19-25 years performed task switching after watching emotional film clips to induce an emotion (neutral, positive, or negative emotions). Two indicators of flexibility were evaluated: (1) the performance decrement reflected by increased reaction time (RT) or errors on the task-switch trial relative to a task-repetition trial, which is known as the "switching cost," and (2) the performance improvement reflected by decreased RT or errors when switching from a task-switching context to a single-task context, which is known as the "fade-out" effect. These indicators reflect cognitive flexibility on short and long time scales, respectively. The results show that negative moods reduced switching costs, particularly in incongruent trials. In addition, negative moods were found to cause a prolonged fade-out effect compared with neutral and positive moods, indicating that participants required more trials to adjust to the single-task condition after experiencing the task-switching context. The result suggests that only negative moods and not positive moods modulated both the short and long time scales of cognitive flexibility but with dissociable effects. Possible explanations are discussed.