The National Institute of Mental Health keeps reward and low mood in separate research domains, and people who can’t simply decide to feel better aren’t lacking willpower or gratitude, they’re dealing with a symptom that responds more slowly than sadness

That distinction sits underneath a claim now circulating in shortened form: that people who cannot simply decide to feel better are not failing at effort or gratitude. Der-Avakian and Markou, reviewing that literature in Trends in Neurosciences in 2012, set out reward processing as motivation, consumption, and learning. Across their development samples the two scales correlated between minus 0.12 and minus 0.23, which the authors called invariably low. A 2020 secondary analysis by Gabriela Khazanov and colleagues, also in Behaviour Research and Therapy, complicates the picture in a useful direction. Reward research also sits in an area with well-documented replication problems, and this literature is not exempt.