Visual navigation is affected by low-dose alcohol use: Not in perception but in visuomotor control

The detrimental effects of alcohol use on driving-related cognition have been widely reported. However, most evidence regarding cognitive impairment focuses on moderate to high blood alcohol concentrations (BAC ≥0.04 g/dl), while the effects at low BAC levels are less frequently discussed and yield mixed results. We investigated whether and how low-dose alcohol consumption at a BAC level of 0.03 g/dl affects visual navigation via optic flow, which features in driving-related tasks.

To examine the distinct effects of low-dose alcohol use on perception and visuomotor control, respectively, we designed two complementary tasks: a static heading estimation task involving passive viewing and discrete heading judgements; and a continuous heading matching task requiring active steering to align with optic flow.

The results showed that low-dose alcohol did not significantly affect the accuracy or precision of heading judgments. However, it increased temporal delay in continuous heading matching and significantly reduced heading matching precision toward optic flow display at higher speed (60 km/h).

Our findings highlight that in visual navigation, visuomotor control, rather than heading perception, is particularly vulnerable to the negative effects of low-dose alcohol use.

This study underscores the methodological importance of adopting more ecologically valid measurements and supports a stricter BAC limit in practical applications to reduce the risk of driving accidents.