Monetary Incentives Reduced Some Cannabis Task Deficits Without Removing Dose-Related Impairment

A 1975 study found that monetary incentives were associated with smaller cannabis effects on some tasks, while dose-related impairment remained evident across most of the battery. Motivation and pharmacological tolerance were not the same question.

Motivated and comparison groups were tested

Experienced and previously naive participants smoked placebo and two cannabis dose levels. Their performance across five tasks was compared with matched groups without the monetary incentive. This design examined whether consequences for performance changed the observed drug response.

The benefit was selective

Four of five tasks showed dose-related impairment. Three suggested that motivated participants were less affected than non-motivated participants. The abstract does not establish complete restoration, and an incentive effect in some tasks should not be expanded to every cognitive function.

Experience did not provide the expected group advantage

The study found no difference between naive and experienced participants in the reported performance comparison. That null result does not establish that use history never matters, but it prevents attributing this experiment's incentive-related differences to demonstrated user tolerance.

The findings show that effort, incentives and drug effects can jointly influence a test score. Better performance under incentive does not prove the drug has stopped acting or establish fitness for driving. The relevant assessment should identify the task, dose and conditions motivating the participant.

Related: interpreting cannabis tolerance claims.

Research cited

Casswell S. Cannabis intoxication: effects of monetary incentive on performance, a controlled investigation of behavioural tolerance in moderate users of cannabis. Perceptual and motor skills (1975). doi:10.2466/pms.1975.41.2.423. Findings discussed from the study abstract.