EVIDENCE LIBRARY
Can Alcohol Slow Word Decisions Without a Clear Increase in Errors?
A 22-person crossover study found slower word decisions after alcohol, with no clear accuracy effect. Brain-signal changes concerned meaning retrieval and response conflict, not a direct measurement of conversational competence.
Yes. In a 22-person crossover experiment, alcohol slowed decisions about words even though the overall accuracy change did not reach conventional significance. Brain recordings also changed during meaning retrieval and response selection. Correct answers alone therefore did not capture every alcohol-related effect.
The word task required competing response rules
Marinkovic and colleagues tested eleven men and eleven women, all healthy social drinkers. Each completed alcohol and placebo sessions in counterbalanced order. The alcohol dose was 0.60 grams per kilogram for men and 0.55 for women.
Participants pressed one button for ordinary real words and another when the word named an animal. They withheld responses to nonwords. This required recognizing meaning, applying a special category rule and choosing or withholding a response.
The task began approximately thirty-eight minutes after drinking. Mean breath-derived BAC-equivalent readings were approximately 0.044% before and after testing. These group averages were breath estimates, not laboratory blood measurements or proof of an identical concentration curve in every person.
Speed changed more clearly than accuracy
Mean reaction time was 811 milliseconds after alcohol and 777 after placebo, a significant overall slowing. Accuracy was only marginally lower overall, with the reported p value below .09 rather than below .05. Alcohol-placebo accuracy comparisons within individual stimulus conditions were not significant.
Animal-category trials were less accurate than the other conditions overall. That task-difficulty effect should not be mistaken for a demonstrated alcohol-specific increase in animal-word errors.
Participants rated task difficulty similarly across beverages. Their impression that the task remained manageable did not exclude the measured slowing.
The brain findings concerned task-related theta activity
Researchers recorded magnetoencephalography, or MEG, alongside limited scalp EEG. MRI-based anatomical information constrained estimates of the brain sources of theta-frequency activity.
Real words produced different theta responses from pronounceable pseudowords. Alcohol reduced several task-related responses, including signals associated with meaningful-word processing and with the additional response conflict imposed by animal words.
These were estimated sources of electrical activity, not direct recordings from electrodes within those brain regions. Localization assumptions and the wavelet method’s temporal smearing limit how precisely the activity can be placed in space and time.
What correct-response recordings can and cannot show
The main imaging analysis included correct trials and equalized their number across conditions. That helped comparisons, but it means the reported neural pattern was not a direct analysis of the mechanism of mistakes.
No systematic change in prestimulus theta explained the task-related findings. Reduced event-related activity therefore should not be relabeled as proof that all resting brain activity was suppressed or that a person had a general EEG disorder.
Relevance to instructions and DUI interpretation
Understanding an instruction and responding efficiently can involve several processes beyond giving the eventual correct answer. This experiment supports that distinction in a constrained word task.
It did not test ordinary conversation, roadside instructions, road-sign reading or driving. It cannot establish that a specific person misunderstood an instruction or was unable to drive. The small selected sample and participants’ awareness of beverage contents also limit generalization and leave expectancy effects incompletely separated.
The site’s speech-listening experiment examines a different language-related demand. Word decisions on a screen and selecting speech from competing input require separate evidence.
Primary source
Marinkovic K, Rosen BQ, Cox B, Kovacevic S. Event-related theta power during lexical-semantic retrieval and decision conflict is modulated by alcohol intoxication: anatomically constrained MEG. Frontiers in Psychology. 2012;3:121. https://doi.org/10.3389/fpsyg.2012.00121.