A significant 5-HTTLPR genotype by Spray interaction was observed for both Caucasian (F (2,40) = 10.01, p = 0.003) and African-American (F (2,38) = 7.35, p = 0.002) smokers. Subsequent pair-wise comparisons parsing the 5-HTTLPR genotype X Spray interaction indicated that smokers with the l/l genotype of the 5-HTTLPR gene showed significantly greater startle suppression when provided with nicotine vs. placebo, compared with smokers carrying the s allele. There was no interaction with deprivation status or slide valence, though the main effect of valence was significant in African Americans (F (3,38) = 6.95, p < 0.0008) and Caucasians (F (4,40) = 16.6, p < 0.0001), confirming the expected ordering of the startle responses to each of the stimuli in both groups. Main effects due to deprivation and spray were not significant.
