Individual differences in dopamine level modulate the ego depletion effect

• The ego depletion effect can be considered as a phenomenon similar to “switch costs”.
• Dopamine level and flexible switching shows an inverted-U-shaped relationship.
• Eye blink rate (EBR) provides a reliable behavioral measure of dopamine level.
• We found an inverted-U-shaped relationship between EBR and ego depletion.

Initial exertion of self-control impairs subsequent self-regulatory performance, which is referred to as the ego depletion effect. The current study examined how individual differences in dopamine level, as indexed by eye blink rate (EBR), would moderate ego depletion. An inverted-U-shaped relationship between EBR and subsequent self-regulatory performance was found when participants initially engaged in self-control but such relationship was absent in the control condition where there was no initial exertion, suggesting individuals with a medium dopamine level may be protected from the typical ego depletion effect. These findings are consistent with a cognitive explanation which considers ego depletion as a phenomenon similar to “switch costs” that would be neutralized by factors promoting flexible switching.