Cannabis, Tablet Tests and the Tradeoff Between Speed and Accuracy
A normal or improved accuracy score after cannabis use can coexist with slower performance. In a tablet-based study, daily users took longer on a gap-acceptance task while improving their success rate. Looking at either speed or accuracy alone would leave out part of the result.
How the study separated use patterns
Brooks-Russell and colleagues studied 86 adults: 32 who were not currently using cannabis, 23 occasional users and 31 daily users. Participants completed reaction-time, gap-acceptance and shape-memory tasks before and after the testing interval. Cannabis users consumed their own flower products rather than a uniform, experimentally assigned dose.
The non-use group provided a comparison for changes associated with repeating the tests. That matters because practice can improve performance even without a drug effect. The analyses compared changes from baseline while adjusting for age and gender.
Different tasks revealed different patterns
Occasional users showed worse reaction-time and shape-memory changes than non-users. Daily users did not show the same pattern on those outcomes. However, their gap-acceptance completion time increased, while the other groups completed the task more quickly at retesting.
The daily-use group also improved its gap-task success ratio relative to the non-use group. The overall group test for that accuracy outcome was marginal at p = 0.05, and the daily-versus-non-use comparison was significant. The result warrants reporting as a speed–accuracy pattern, without declaring either global impairment or global preservation.
Why the result is not a roadside clearance test
The groups were not randomized to become occasional or daily users. Their histories, baseline performance and self-administered exposure could differ. A tablet task also does not reproduce the full demands of driving, and a blood measurement cannot make unequal doses equivalent.
The journal later corrected the competing-interest disclosure to identify an author’s editorial role; the notice did not report a change to the outcome data. See the published correction.
For a case involving apparently normal performance, the useful question is which function was measured and what tradeoff the scoring system allowed. Our analysis of finger tapping and balance after cannabis concentrates illustrates another reason that one preserved task cannot stand in for a complete functional assessment.
Primary research
Effects of acute cannabis inhalation on reaction time, decision-making, and memory using a tablet-based application. DOI: 10.1186/s42238-024-00215-1.
