Contrary to previous research on the BART in adolescent and young adult smokers (Lejuez et al. 2002
), we did not find smokers to exhibit greater risk-taking than nonsmokers on standard BART composite indices (e.g., pumps, explosions, pumps after explosions, and variability). In fact, in analyses at the balloon trial level, the smokers and nonsmokers showed differential adaptation in risk behavior, with the nonsmokers exhibiting progressively more pumping relative to the smokers over the course of the task, regardless of the type of risk condition. Both groups pumped more overall on the low-risk balloons than the high-risk balloons. The group effects we observed were not attributable to demographic, substance abuse, or mood variables.
Because our study employed more rigorous exclusion of drug use and psychiatric comorbidities than previous studies (Lejuez et al. 2002
), the relatively limited risky behavior exhibited by our smoking group may have been attributable to the removal of those with potentially risk-prone comorbidities; in other words, young adult smokers who do not have substance abuse problems or psychiatric comorbidities may not engage in risky behaviors. However, we find this explanation unlikely, as the absence of drug abuse and psychiatric diagnoses from the smoking group would not explain why the smokers displayed a significantly more risk averse
pumping strategy than the nonsmokers over the course of the BART assessment. Further, the smoking group otherwise performed in a manner that would imply higher rates of risky or impulsive behavior than nonsmokers. For example, the smokers had a greater tendency to discount delayed rewards than the nonsmokers, and they had higher levels of motor impulsivity. In addition, despite the removal of those with substance abuse diagnoses, the smokers endorsed using alcohol on more of the previous 30 days than nonsmokers, as well as a trend towards more use of marijuana (p
.05). Nonetheless, given the exclusion of drug abuse and psychiatric comorbidities from our smoking group, our BART findings may only be generalizable to smokers who do not have comorbid conditions.
Although divergent from some previous research (Lejuez et al. 2003
), the absence of significant differences in mean adjusted pumps between smokers and nonsmokers is similar to the results of Acheson and de Wit (2008
), who also did not find a group effect for adjusted pumps in a small sample of smokers (n
10) and nonsmokers (n
20) in a study assessing the effects of medication on the BART. Similarly, not all research has suggested that adjusted pumps on the BART are positively associated with maladaptive traits or psychopathology. For example, in a recent investigation, Ray and Ashenhurst (2010
) found that BART adjusted pumps and post-explosion pumps were negatively
associated with alcohol problem behaviors in a sample of 51 participants with alcohol use disorders. Humphreys and Lee (manuscript under editorial review) similarly found that, after controlling for symptoms of oppositional defiance, ADHD symptoms were negatively
related to adjusted pumps and post-explosion pumps in a large sample (n
111) of ethnically diverse children aged 6 to 9.
Additional insight into the nature of our findings was provided by examination of relationships between BART performance and measures of mood, impulsivity, and demographic characteristics. Adjusted pumps on the BART were positively related to years of education, with a trend for a positive relationship between adjusted pumps and estimated nonverbal IQ (p
.051). A small subset (n
5) of individuals with very high delay discounting scores also had low levels of pumping on the BART. This perhaps suggests that these individuals preferred the immediate reward of “cashing in” early, rather than persisting with pumping to earn, or lose, greater sums of money.
With respect to pumping trajectories, employed participants tended to increase their pumping over trials to a greater extent than those who were unemployed (p
.055). While perhaps those without a job were more risk averse because they perceived the money earned on the BART to be of more value than those who were employed, we did not find a relationship between BART performance and the median income of the city in which participants resided (some unemployed subjects were students receiving money from other sources), nor did we find a relationship between BART performance and parental education levels, a common proxy for socioeconomic background (Bradley and Corwyn 2002
). Importantly, controlling for the effect of employment did not alter the trajectory differences found between smokers and nonsmokers on the BART.
Our overall findings suggest that greater pumping on the BART was related to positive traits (e.g., nonsmoking, employment, years of education, and higher IQ). Although divergent from studies of other patient groups, these results are consistent recent studies demonstrating negative relationships between pumping and dysfunctional symptoms in other populations (Humphreys and Lee, manuscript under editorial review; Ray and Ashenhurst 2010
). It is also important to note that, as a result of their pumping trajectories, nonsmokers made a nonsignificantly greater amount of money on the task than smokers. Further, neither the smokers or the nonsmokers exhibited mean adjusted pumps that came close to exceeding the optimal reward/risk ratio for either balloon risk condition (“low-risk” balloons, smoker mean
22.9; nonsmoker mean
26.6; optimal mean
64 (Lejuez et al. 2002
); “high-risk” balloons, smoker mean
11.2; nonsmoker mean
10.9; optimal mean
16 (Lejuez et al. 2002
)). This is further exemplified by the strong positive correlation between explosions and total money earned on the BART (r
.000). In other words, participants who pumped more on the task generally made more money than those who were more conservative.
These findings indicate that, at the levels of risk-taking demonstrated here, pumping was generally adaptive, not maladaptive. This is a common occurrence in studies of the BART, in which participants rarely exceed the optimal level of pumps, regardless of the population under investigation (see Lejuez et al. 2002
; Pleskac et al. 2008
). Thus, although excessive pumping on the BART has been associated with maladaptive traits, low levels of pumping may also be indicative of poor decision-making. Because risks are present to varying degrees in the day-to-day activity of living, these data serve as a reminder that the ultimate adaptiveness of a potentially risky action is based not only on the consequences of acting but also on the consequences of failing to act. Further, since the pumping trajectories exhibited by nonsmokers were associated (nonsignificantly) with earning more money on the task, it may be a misnomer to characterize their behavior as “riskier” than the smokers. Rather, relative to the smokers, their behavior may be better described as reward sensitive.
Although differences between our BART and the BART(s) used by Lejuez and colleagues might account for the differences in results between the studies, we generally find this explanation inadequate. In the original BART validation study, three balloon colors were used with three different initial explosion probabilities: 1/8, 1/32, and 1/128. The balloons with higher explosion probabilities were primarily included as a means to ensure that some balloons exploded (Lejuez et al. 2002
), and adjusted pumps on just the lowest probability balloon (1/128) was used as the primary dependent variable in this and subsequent studies (Lejuez et al. 2003
). Our study included two probabilities of explosion: 1/32 (“high risk”) and 1/128 (“low risk”). The higher risk condition (1/32 initial probability) was sufficient to ensure explosions, and thus, we do not suspect that differences in explosion probability account for the differences in our results. Further, differences between our study and previous studies are also unlikely to be attributable to the number of balloon trials used. We found significant differences in pumping trajectories using a smaller number of trials: 40 total balloons (20 per condition) vs. previous studies with 90 balloons (30 per color, Lejuez et al. 2002
) and 30 balloons (one color, Lejuez et al. 2003
), respectively, the latter of which reported relatively parallel trajectories for smokers and nonsmokers.
Because we used only two balloon risk conditions and wished to reduce the effect of learning on pumping behavior, we informed participants beforehand that “one [balloon] color is more likely to explode than the other.” While it is possible that nonsmokers took advantage of this information to a greater extent than smokers, it is clear that both smokers and nonsmokers discriminated between the low-risk and high-risk balloons almost from the beginning of the task (see Fig. ). Moreover, these instructions would not explain why smokers displayed risk averse pumping trajectories compared to the nonsmokers on the high-risk balloon type.
Previous studies examining the relationship between smoking and the BART have varied in the rewards used for pumping behavior: the original validation study gave participants 5 cents per pump (Lejuez et al. 2002
), while later studies rewarded participants for total points on the task with movie tickets, gift cards, or a flat payment of $10 (Lejuez et al. 2003
). These values are grossly similar to our study, in which participants received 2 cents per pump, earning them between $1.90 and $20.00 on the task. In addition, previous research suggests that paying only 1 cent per pump is a sufficient incentive to demonstrate greater pumping in adolescents with conduct problems and substance abuse compared to control subjects (Crowley et al. 2006