People who scored higher in sensation seeking worked more for d-amphetamine under a laboratory reinforcement procedure. That behavioral outcome is related to, but distinct from, reporting that a drug feels pleasant.
The study compared ten high sensation seekers with ten low sensation seekers matched on several characteristics. Participants first sampled placebo and 8- and 16-mg d-amphetamine doses. In later sessions they could work for the previously sampled dose using a modified progressive-ratio procedure.
As response requirements increase, the procedure assesses how much effort someone will expend for the drug under those conditions. It is an experimental measure of reinforcement, rather than a clinical diagnosis of dependence.
D-Amphetamine functioned as a reinforcer and produced typical stimulant-like subjective effects, performance changes and increased heart rate. High sensation seekers were more sensitive to reinforcing effects and some subjective effects than low sensation seekers.
The word “some” matters: a difference on a reinforcement measure should not be assumed to occur on every physiological or performance endpoint. Nor are pleasantness ratings and willingness to work interchangeable measurements.
The investigators matched groups on factors including age, education and drug use. Nevertheless, the groups could differ in unmeasured characteristics. Sensation-seeking status itself was not experimentally assigned.
The small sample and the particular task, doses and opportunities constrain generalization. Laboratory willingness to work for a dose does not establish what an individual will do in an unrestricted environment.
The findings suggest one pathway through which individual differences may relate to drug-taking vulnerability. They do not demonstrate that every high sensation seeker will develop misuse or that a low score prevents it.
The paper also provides no measure of driving impairment. Reinforcing effects, performance effects, cardiovascular responses and drug concentrations remain separate parts of an assessment, each requiring evidence appropriate to its question.
Related reading: Why faster responses can accompany more errors.