EVIDENCE LIBRARY
Does Alcohol Affect Recognizing Old Images Differently From Rejecting New Ones?
A 90-person study found alcohol effects depended on age, dose and whether images were old or new. Why selected benefits and null findings cannot establish driving fitness.
Yes. In a 90-person experiment, alcohol’s effects on visual working-memory performance depended on age, dose and whether an image had appeared before. Older adults at the lower target dose showed better performance on some previously seen-image measures, while the higher target dose was associated with poorer correct-rejection efficiency compared with placebo. The findings do not support a blanket claim that alcohol either uniformly improves memory or uniformly impairs every task.
Boissoneault and colleagues’ 2014 primary study helps explain why a driver’s successful recognition response cannot stand in for a complete assessment of cognition. Recognizing an old image and correctly rejecting a new one are distinct response categories.
Who was tested and what alcohol values meant
The investigators studied 39 older social drinkers aged 55–70 and 51 younger drinkers aged 25–35. Participants were randomly assigned to placebo or beverages targeting breath-reported concentrations of 0.04 or 0.065 g/dL in a double-blind, between-person design.
The exposure readings came from breath testing, including an Intoxylizer 400PA. These were not serial whole-blood ethanol assays. The dose targets should not be confused with each person’s achieved concentration. The paper reports that breath values were higher around working-memory testing than around the earlier Trail Making Test, and five participants received active booster beverages under the protocol.
Thus, the two cognitive tasks were not necessarily performed at identical exposure levels. Serum/plasma, urine and longer-window biomarkers were not interchangeable measures of the alcohol concentration during these tasks.
Old-image recognition and new-image rejection
Participants viewed faces and scenes and were instructed to remember one type while ignoring the other. After a delay, they judged whether a probe image had appeared in the preceding sequence. Correctly endorsing an old image was a hit; correctly identifying a new image as absent from the sequence was a correct rejection.
The researchers examined accuracy, response time and efficiency calculated as accuracy divided by response time. An efficiency score can change because accuracy changes, speed changes or both. It cannot be interpreted as a direct anatomical measure of memory or a validated driving-impairment score.
Some apparent improvements require qualification
Older participants in the lower target-dose group showed higher hit efficiency than older placebo participants in a planned comparison (p = .03). But the overall age-by-dose interaction for that hit-efficiency outcome was only trend-level (p = .09), rather than significant at .05.
That distinction matters. The subgroup comparison is a reported result, but it is not proof of a robust general age-specific enhancement. Hit accuracy findings also included borderline or trend-level comparisons, while hit reaction time showed no significant alcohol effect. Younger participants did not show significant dose effects on hit efficiency.
Possible attentional narrowing was discussed as an explanation, not directly established. Nothing in this selected laboratory advantage demonstrates improved awareness of road hazards or safer driving after alcohol.
Rejecting new images produced a different pattern
The age-by-dose interaction for correct-rejection efficiency was significant (p = .02). Older adults in the higher target-dose group were less efficient than older placebo participants (p = .04). Some younger-group comparisons showed different or trend-level patterns depending on whether participants were remembering faces or scenes.
Across age groups, correct-rejection accuracy was lower at the higher target dose: approximately 88.6%, compared with 94.8% for placebo and 93.2% at the lower target dose. Not every speed difference was significant. In particular, the paper’s age-by-dose interaction for correct-rejection reaction time was trend-level, not a definitive alcohol-related slowing effect.
The supported conclusion is task- and outcome-dependent performance, not a universal loss of memory and not a universal protective effect of younger age.
Trail making also resisted a simple impairment label
The lower target dose was associated with faster performance on the simpler Trail Making Part A across age groups. For the more complex Part B, older participants at the higher target dose were slower than older participants at the lower dose, but the comparison with older placebo participants was not significant.
Reporting only the higher-versus-lower dose difference would conceal the null placebo comparison. These results illustrate why choosing one favorable or unfavorable comparator can distort a scientific account.
Limits of the experiment
Different people received the different doses, leaving more room for individual variation than a within-person crossover. Dose groups also differed on some background measures. Medication use was permitted under eligibility conditions and was more common among older participants. Sleep and some other possible influences were not measured.
Several findings followed trend-level interactions or planned subgroup comparisons without additional multiplicity correction. The recognition task was relatively simple and susceptible to ceiling effects. Participants did not provide confidence ratings needed for the more comprehensive signal-detection analysis the authors considered.
The study did not test driving, quantify crash risk or establish an individual diagnostic threshold. Its average age differences cannot justify declaring a particular older driver impaired or a younger driver unaffected.
How to apply it to DUI observations
Identify what a person actually recognized, rejected, remembered or did, rather than treating “memory” as a single all-or-nothing ability. Separate errors from response time and distinguish observed test results from concentration estimates.
The finding complements the distinction between overall Stroop slowing and an unchanged interference score. Different outcomes within a task can lead to different conclusions. Neither an isolated success nor a group-level deficit settles a driver’s functional state or legal status.
Primary source
Boissoneault J, Sklar A, Prather R, Nixon SJ. Acute effects of moderate alcohol on psychomotor, set shifting, and working memory function in older and younger social drinkers. Journal of Studies on Alcohol and Drugs. 2014;75:870–879. https://doi.org/10.15288/jsad.2014.75.870.