Can the use of multiple stop signals reduce the disinhibiting effects of alcohol?

BACKGROUND: Research has consistently demonstrated that alcohol impairs the ability to divide attention across 2 or more stimuli. However, under certain circumstances, the presentation of multiple stimuli can actually facilitate performance. The "redundant signal effect" (RSE) refers to the phenomenon by which individuals respond more quickly and accurately when information is presented as redundant, bimodal stimuli (e.g., visually and aurally), rather than as a single stimulus presented to either modality alone. Recent work has shown that reaction time (RT) to redundant signals is hastened under alcohol, ameliorating the slowing effects of the drug. However, no research has examined whether RSE can reduce the impairing effects of alcohol on the ability to inhibit behavior. METHODS: This study examined whether the impairing effects of alcohol on inhibitory control might be altered by the presentation of redundant inhibitory signals. Inhibitory control was assessed by a go/no-go task which included single and redundant inhibitory signals. Performance was tested following placebo (0.0 g/kg) and alcohol (0.65 g/kg). The effect of redundant activation signals on alcohol impairment of response activation was also measured. RESULTS: The results showed evidence for RSE on the activation of behavior, but not for inhibitory control. Compared with placebo, alcohol slowed RT and reduced response inhibition. Redundant signals had a robust speeding effect on RT, even following alcohol. By contrast, redundant signals failed to improve inhibitory control following placebo or alcohol. CONCLUSIONS: These findings have important implications for understanding how drinkers respond to multimodal signals in their everyday environments and highlight the vulnerability of inhibitory control to alcohol's impairing effects.