This narrative review traces how the scientific understanding of psychedelics has intersected with "reward processing" from before the Controlled Substances Act (CSA) era to the present, emphasizing how cultural and regulatory climates shaped what was viewed as an acceptable research question. Reward processing is treated as a family of partially overlapping phenomena: (1) reward-linked behavior (e.g., self-administration, conditioned place preference, reinstatement), (2) reward-circuit signals (e.g., mesolimbic dopamine dynamics, electrophysiology, human electroencephalography potentials), and (3) clinically relevant outcomes in substance use disorder (SUD) (e.g., withdrawal severity, consumption, relapse). Across these measures, the literature repeatedly adopts two framing logics: "liability framing," which prioritizes misuse potential and dependence risk, and "therapeutic framing," which treats psychedelics as tools for probing and potentially reconfiguring reward circuitry and learning. Organized by decade, the review shows that the 1960s already contained both motifs, with adjunctive therapeutic hopes alongside early reinforcement assays, while the CSA era increasingly systematized a hazard-first posture that defined the late 1970s through the 2000s, referred to as the "psychedelic dark age." Within those constraints, monoamine and receptor pharmacology (including serotonin-dopamine interactions) became a dominant tool for investigating reward, and ibogaine programs loudly reintroduced a therapeutically oriented anti-addiction narrative. In the 2000s, serotonergic control of dopaminergic reward systems and entactogen models, including social reward, broadened the mechanistic frame. In the 2010s and 2020s, the field's momentum shifted toward therapeutic models, circuit plasticity, computationally interpretable reward signals, and renewed clinical work in SUD. The review argues that a central bottleneck is not a lack of provocative acute findings but rather a lack of experimental programs that bridge behavior, circuit signals, and longitudinal clinical endpoints. We therefore propose that revisiting important concepts and findings discussed herein with recently developed technology and approaches (e.g., cue-evoked signals, learning parameters, photometry) across dose, time, and sex would advance the field. We highlight practical study shifts to move toward an integrated account of how psychedelics modulate reward-relevant brain activity and behavior.
