Behavioral response bias and event-related brain potentials implicate elevated incentive salience attribution to alcohol cues in emerging adults with lower sensitivity to alcohol

Aims
This study used a behavioral approach-avoidance task including images of alcoholic beverages to test whether low sensitivity to alcohol (LS) is a phenotypical marker of a dispositional propensity to attribute bottom-up incentive value to naturally conditioned alcohol cues.
Design, setting and participants
Experimental study with a measured individual difference variable at a university psychology laboratory in Missouri, MO, USA. Participants were 178 emerging adults (aged 18–20 years) varying in self-reported sensitivity to alcohol's acute effects.
Measurements
Participants completed the alcohol approach-avoidance task while behavior (response time; RT) and the electroencephalogram (EEG) were recorded. Stimulus-locked event-related potentials (ERPs) provided indices of integrated (top-down and bottom-up) stimulus incentive value (P3 amplitude) and conflict between top-down task demands and bottom-up response propensities (N450 amplitude).
Findings
Linear mixed models showed faster RT for ‘alcohol-approach’ relative to ‘alcohol-avoid’ trials for lower-sensitivity (LS) [mean_D ± standard error_D (M_D ± SE_D) = 29.51 ± 9.74 ms, t₍₃₂₈₎= 3.03, P = 0.003] but not higher-sensitivity (HS) individuals (M_D ± SE_D = 2.27 ± 9.33 ms, t₍₃₂₈₎ = 0.243, P = 0.808). There was enhanced N450 amplitude (response conflict) for alcohol-avoid relative to alcohol-approach trials for LS participants (M_D ± SE_D = 0.811 ± 0.198 μV, Z = 4.108, P < 0.001) and enhanced N450 amplitude for alcohol-approach relative to alcohol-avoid for HS participants (M_D ± SE_D= 0.419 ± 0.188 μV, Z = 2.235, P = 0.025). There was also enhanced P3 amplitude for alcohol-approach relative to alcohol-avoid for LS (M_D ± SE_D = 0.825 ± 0.204 μV, Z = 4.045, P < 0.001) but not HS (M_D ± SE_D= 0.013 ± 0.194 μV, Z = 0.068, P = 0.946).
Conclusions
Findings from a human laboratory study appear to support the notion that low sensitivity to alcohol indexes a propensity to attribute bottom–up incentive value to naturally conditioned alcohol cues.