presents means and standard deviations for neonatal and environmental risk scores and amount of in utero exposure to alcohol, cigarettes, marijuana, and cocaine. Cocaine-exposed versus -unexposed children had significantly greater neonatal complications, F(1, 169) = 9.14, p < .01, and were exposed in utero to greater amounts of alcohol, F(1, 165) = 32.31, p < .001; cigarettes, F(1, 165) = 54.10, p < .001; and marijuana, F(1, 164) = 4.96, p < .05. However, environmental risk did not differ between cocaine-exposed and -unexposed children, and there were no gender or Gender × Exposure differences in the risk factors. These risk factors were not significantly correlated with the dependent variables (reactivity and regulation variables; correlations between −.13 and .14). We examined correlations between risk factors and outcomes separately for cocaine-exposed versus -unexposed children, and associations remained nonsignificant. Next, because child IQ might be associated with problem-solving ability, correlations between child IQ and outcome variables were examined (child IQ M = 84.14, SD = 11.47, range = 54 –111). There were no significant correlations. Finally, all analyses of variance (ANOVAs) reported below were initially conducted using neonatal and environmental risk scores and child IQ as covariates, including their interactions with exposure group and gender. Results did not differ from those analyses without covariates. Thus, analyses without risk factors and IQ as covariates are reported below.
Descriptive Statistics for Neonatal and Environmental Risk Scores and Amount of In Utero Exposure to Alcohol, Cigarettes, Marijuana, and Cocaine
The dependent variables are located in the left-hand column of . Correlational analyses were used to evaluate the relations among these measures. The pattern of correlations was comparable across the four Exposure × Gender groups. Significant intercorrelations indicated that the greater the number of instrumental behaviors, the shorter the latency to approach the task, r = −.29, p < .001, but the longer the latency to attempt to untie the knot, r = .34, p < .001. This was perhaps because children using instrumental behaviors also used other problem-solving strategies before attempting the knot. The number of instrumental behaviors also was correlated positively with disruptive behaviors, r = .15, p < .05, perhaps reflecting the general level of activity. Finally, as might be expected, the greater the number of disruptive behaviors, the shorter the latency to express frustration, r = −.62, p < .001.
Descriptive Statistics for Outcome Variables
These correlations suggest that reactivity and regulation scores were largely independent. However, to further explore the independence of these constructs, we examined whether children who expressed frustration relatively quickly or slowly (reactivity) differed in their problem-solving behavior during the task (regulation). Of the 174 children in this study, 88 children never showed frustration. For the remaining 86, we created two groups based on a median split (50th percentile = 19 s). These groups did not differ on our measures of regulation (latency to approach the task and latency to first attempt to untie the knot, number of instrumental behaviors). This further suggests that reactivity and regulation are independent dimensions.
presents the means, standard deviations, and proportion scores for the dependent variables. To examine cocaine exposure and gender differences in child reactivity and regulation, we conducted a separate univariate ANOVA for each of the five dependent variables: latency to first evidence of frustration, number of disruptive behaviors, latency to approach the task, latency to first attempt to untie the knot, and number of instrumental behaviors. Substance exposure group and gender were the between-subjects factors. A high proportion of children did not receive scores for one or more of the behavioral codes. For example, 24.1% of children did not attempt the knot and 50.6% did not show frustration and thus did not have latency scores. Therefore, each ANOVA was followed by a chi-square analysis to examine cocaine exposure and gender group differences in the proportion of children who (a) showed frustration; (b) showed no, low, or high levels of disruptive behavior; (c) approached the task immediately; (d) attempted the knot; and (e) showed low versus high levels of instrumental behavior.
The ANOVA for latency to express frustration revealed a significant interaction between exposure and gender, F(1, 173) = 3.76, p < .05, η2 = 2%. Cocaine-exposed boys showed a significantly shorter latency to express frustration than did cocaine-unexposed boys, t(89) = 2.38, p < .05; cocaine-exposed girls, t(63) = 2.32, p < .05; and cocaine-unexposed girls, t(74) = 2.12, p < .05. There were no differences in frustration latency among cocaine-exposed girls and -unexposed girls and boys. Chi-square analyses further indicated that a greater proportion of cocaine-exposed boys versus cocaine-exposed girls showed frustration, χ2(1, N = 174) = 4.56, p < .05. Differences among cocaine-exposed boys, cocaine-unexposed boys, and cocaine-unexposed girls were not significant.
For the disruptive behaviors composite, the interaction between cocaine exposure and gender also was significant, F(1, 173) = 5.50, p < .05, η2 = 3%. Follow-up tests revealed trends for cocaine-exposed boys to evidence more disruptive behaviors than cocaine-unexposed boys, t(89) = 1.81, p < .07, and cocaine-exposed girls, t(63) = 1.85, p < .07, but they did not differ from cocaine-unexposed girls. Chi-square analyses confirmed these trends, revealing significant Exposure × Gender group differences in the proportion of children showing no, low, or high levels of disruptive behaviors, χ2(2, N = 174) = 6.48, p < .05. Follow-up chi square analyses for each level of disruptive behavior found that only the proportion of children showing no disruptive behavior differed significantly among groups, χ2(1, N = 174) = 5.15, p < .05. A smaller proportion of cocaine-exposed boys showed no disruptive behavior compared with cocaine-exposed girls, cocaine-unexposed boys, and cocaine-unexposed girls. The differences among cocaine-exposed girls, cocaine-unexposed boys, and cocaine-unexposed girls were not significant. Also, the differences between cocaine-exposed and -unexposed children and between boys and girls for low or high levels of disruptive behaviors were not significant.
Analyses of latency to approach the task did not reach significance, but analyses of latency to first attempt to untie the knot revealed a significant main effect of cocaine exposure. Cocaine-exposed children took longer to attempt to untie the knot than did cocaine-unexposed children, F(1, 173) = 4.09, p < .05, η2 = 3%. The interaction between cocaine exposure and gender did not reach significance. However, a chi-square analysis examining the proportion of children who attempted the knot yielded a significant Exposure × Gender interaction, χ2(1, N = 174) = 4.44, p < .05. A larger proportion of cocaine-unexposed boys attempted the knot compared with cocaine-unexposed girls, cocaine-exposed boys, and cocaine-exposed girls. The differences among cocaine-unexposed girls, cocaine-exposed boys, and cocaine-exposed girls for latency to first attempt to untie the knot were not significant, and group differences for latency to approach the task also were not significant.
The ANOVA for the instrumental behaviors composite yielded a main effect of gender, F(1, 173) = 4.04, p < .05, η2 = 3%, showing that girls evidenced more instrumental behaviors than did boys. Chi-square analyses for instrumental behavior did not reach significance.