Assumptions of normality and homogeneity of variance were met satisfactorily for the dependent variables and there were no order effects for the gambling scene presentations. The sample’s mean score on the SOGS was 4.85 (SD = 4.45); 42.6% of the participants scored in the normal range, 14.9% were possible problem gamblers, and 42.6% were probable pathological gamblers (SOGS ≥5). These scores were consistent with the NODS, which identified the same 42.6% as meeting DSM-IV criteria for pathological gambling (≥’’5 of 10 symptoms) while 57.4% fell in the normal range (0–4 symptoms).
Correlations between the dependent variables and SOGS, NODS, and demographics were non-significant. Horse race gamblers and scratch-off lottery players were similar in SOGS and NODS scores, age, and education (the latter approached significance with p = .09). Significant group differences existed in gender [χ2(1) =15.82, p <.001], ethnicity [χ2(3) =30.41, p <.001], and household income [χ2(5) =12.46, p = .029]. Compared to horse race gamblers, more scratch-off players were women, African American, and had lower incomes. These three variables were used as covariates in the analyses below.
Primary Analyses of horse race versus lottery gamblers
A 2 X 4 repeated measures multivariate analysis of covariance (MANCOVA) was conducted with group (horse race gamblers, lottery gamblers) as between-subjects factor and cue (mental arithmetic, preferred gambling, non-preferred gambling, car race) as the repeated within-subjects factor. The dependent variables were HR corrected for baseline, excitement and urge to gamble. Gender, ethnicity, and income served as covariates. The MANCOVA yielded significant main effects for group [Wilk’s Lambda = .892, F (3, 87) = 3.26, p <.02, ηp2 = 0.11] and cue [Wilk’s Lambda = .742, F (9,81) = 3.13, p = .003, ηp2 = 0.26] and a significant group by cue interaction [Wilk’s Lambda = .558, F (9,81) = 7.12, p <.001, ηp2 = 0.44]. An examination of the interaction effect, using Sidak-corrected pairwise comparisons, showed similar HR patterns in the two groups (see ). HR elevations in beats per minute (bpm) above baseline of scratch-off lottery gamblers (M = 8.09, SD = 6.42) and horse race gamblers (M = 10.87, SD = 7.29) were highest (p < .01) in response to the mental arithmetic task. HRs to the other cues were significantly lower and did not differ among each other (p ≥ .70). Both groups also showed the same pattern in regards to excitement (see ). Both scratch-off gamblers (M = 43.91, SD = 24.57) and horse race gamblers (M = 25.85, SD = 24.11) reported the lowest excitement to the mental arithmetic task. The horse race gamblers rated the horse race (M = 62.02, SD = 23.44) as more exciting (p <.001) than the scratch-off lottery cue (M = 32.64, SD = 22.17), though not more exciting (p = .75) than the car race (M = 58.26, SD = 2.59). The scratch-off lottery players showed the same pattern, also rating the horse race (M = 70.49, SD = 28.18) and car race (M = 64.72, SD = 27.87) as equally exciting (p = .99), and more exciting (p =.001) than the scratch-off lottery cue (M = 54.49, SD = 27.27). In sum, action cues (horse race and car race) were viewed as more exciting than the other cues. Regarding the urge to gamble (see ), both groups reported the highest urge (p <.01) when exposed to cues of their preferred gambling activity (scratch-off gamblers M = 56.26, SD = 4.66; horse race gamblers M = 53.38, SD = 4.66). Urge ratings to the other three cues were all significantly lower (p ≤ .005), with urges in response to the mental stressor being lowest and urges in response to the non-preferred gambling activity and the car race not differing from each other.
Heart rate increases above baseline in beats per minute of scratch-off lottery players and horse race gamblers
Subjective excitement of scratch-off lottery players and horse race gamblers
Urge to gamble of scratch-off lottery players and horse race gamblers.
Exploratory analysis of pathological versus social gamblers
As 40 of the 94 gamblers (42.6%) met criteria for pathological gambling on both the NODS and the SOGS, we conducted an exploratory analysis to examine cue reactivity as a function of diagnostic status. F-tests and chi square tests showed that the pathological and social gamblers did not differ significantly in gender (p =.74), ethnicity (p =.47), education (p =.07), household income (p = .07), or preferred mode of gambling (p = 0.49); and there were no order effects of gambling scene presentation by diagnostic group (p =.11). A 2 × 4 repeated-measures MANOVA was conducted with diagnostic group (pathological versus social gambler) as the between-subjects factor and type of cue as the within-subjects factor. Heart rate, excitement, and urge to gamble served as the dependent variables. The analysis yielded significant main effects for diagnostic group [Wilk’s Lambda = .850, F (3, 90) = 5.31, p = .002, eegr;p2 = 0.15] and cue [Wilk’s Lambda = .428, F (9, 667) = 30.96, p <.001, ηp2 = 0.25]. The group X cue interaction was non-significant [Wilk’s Lambda = .945, F (9, 667) = 1.74, p =.08, ηp2 = 0.02]. Sidak-corrected follow-up tests showed that the pathological and social gamblers did not differ significantly in heart rate (p = .66) or excitement (p = .23), but pathological gamblers reported overall significantly higher urges (M = 48.57, SD = 3.72) than social gamblers (M = 31.00, SD = 3.20) [F (1,92) = 12.82, p =.001, ηp2 = 0.12]. Following up the main effect for cue, the pattern of results was similar to the findings reported in the main analysis above: baseline corrected heart rates were significantly higher (p <.001) in response to the mental arithmetic task (M = 9.3 bpm, SD = .72) than to the other three cues (Ms = 5.1, 6.1 and 5.5; SDs = .47, .58, and .51 for preferred, non-preferred, and generic exciting cue, respectively). Excitement to the preferred gambling cue (M = 58.79, SD = 2.66) and the car race (M = 62.57, SD = 2.59) did not differ (p = .42) and both were higher (p <.001) than excitement to the non-preferred gambling cue (M = 51.94, SD = 3.30) and the mental stressor (M = 35,13, SD = 2.71). Regarding urges to gamble, the preferred gambling scenario elicited greater urges (M = 56.48, SD = 2.92) than all other cues (p <.001). Urge ratings to the other three cues were all significantly lower (p ≤ .001), with urges in response to the mental stressor being lowest, followed by those to the non-preferred gambling activity and the car race, which did not differ from each other.
In sum, heart rates and excitement ratings of pathological and social gamblers showed similar levels and patterns in response to the four cues, except that excitement was highest to the car race and the preferred gambling cue, regardless of whether this was the horse race or the scratch-off scenario. In addition, urges to gamble were overall significantly stronger in pathological gamblers than social gamblers, but both groups showed cue-specificity in that their urges were strongest in response to cues of their preferred gambling activity.