3a). Stability in ANS responses
Cross-task stability in ANS responsivity within the same assessment. Cross-task stability in children’s ANS responses within the same assessment was examined by conducting pairwise Pearson’s correlations among ANS responsivity scores obtained from different tasks. Cross-task stability coefficients in RSA responsivity ranged from .47 to .70 in preschool, .40 to .60 in kindergarten, and .53 to .69 in first grade. Likewise, cross-task stability in PEP responsivity ranged from .52 to .71 in preschool, .38 to .58 in kindergarten, and .58 to .74 in first grade. These findings suggest that there was moderate
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stability in children’s ANS responsivity toward different tasks within the same assessment.
Stability in ANS responses across time. In order to understand whether there was longitudinal stability in children’s ANS responses, pairwise Pearson’s correlations among scores obtained from the same task in preschool, kindergarten, and first grade were examined. For example, stability in children’s sympathetic responsivity toward the Tangrams task was evaluated by examining the correlations among Tangrams PEP responsivity obtained in preschool, kindergarten, and first grade (see Table 11). Given that different emotion regulation tasks were used each year, longitudinal stability was examined for composite scores of emotion regulation tasks (e.g., average of RSA for tasks in preschool and kindergarten) as well as for individual tasks (e.g., Locked Box in preschool and Not Sharing in kindergarten). One major goal of these analyses was to understand whether all or only specific laboratory tasks elicit ANS responses that are stable over time. The second important goal was to understand whether the longitudinal stability in children’s sympathetic responses (PEP responsivity) were similar to the longitudinal stability in children’s parasympathetic responses (RSA responsivity).
For most laboratory challenges, there was modest to moderate levels stability in RSA responsivity over time (see Table 10). Baseline RSA was moderately stable over time (r = .56 - .66, p < .01). In Tangrams, there was moderate stability from preschool and kindergarten (r = .32, p <.01), from kindergarten to first grade RSA (r = .46, p <.01); and from preschool and first grade (r = .31, p <.01). In Go-No-Go, there was no stability in RSA responsivity from preschool to kindergarten (r =.10, NS), but there was modest
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stability from kindergarten to first grade (r = .25, p <.01). The overall emotion regulation RSA responsivity also demonstrated low to moderate stability from preschool and
kindergarten (r = .25, p <.01) and from kindergarten and first grade RSA responsivity (r = .31, p <.01). In regards to individual emotion regulation tasks, there were correlations among some tasks but not others. In particular, RSA responsivity in the Locked Box task in preschool was associated with the Impossible to Open Gift (r = .24, p < .01) but not with the Not Sharing task (r = .08, NS). The Toy Removal task was associated with all kindergarten emotional tasks (r = .21-.24, p < .01). All kindergarten emotion regulation tasks were associated modestly with the first-grade emotion regulation tasks (r = .15-.30, p < .01).
Although there was moderate stability in baseline PEP over time (r = .49 - .57, p < .01), there was no longitudinal stability in PEP responsivity in most laboratory
challenges. In Tangrams, there was no stability in PEP responsivity from preschool to kindergarten (r = .12, NS), but there was modest stability from kindergarten to first grade (r = .26, p < .01). There was no stability in PEP responsivity in Go/No-Go or in emotion tasks.
3b). Developmental continuity/change and growth in ANS responses. Developmental continuity and change in ANS responses toward laboratory challenges were examined by conducting repeated measures ANOVAs in SPSS. In these analyses, the independent variable was time of assessment, whereas the dependent
variable was the ANS score of interest. Given that sphericity is a main assumption of reseated-measures ANOVA, if there was a violation of sphericity (as indicated by a
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significant Mauchly’s test), the Greenhouse–Geisser correction was applied (Greenhouse & Geisser, 1959). If there was a significant main effect of time, pairwise t-tests were conducted to determine whether and when there was change/discontinuity in children’s physiological responses. If results from the repeated-measures and paired wise t-tests provided evidence for a consistent pattern of change across time (e.g., increase in values from preschool to first grade), then linear growth modeling was used to test whether there was a linear pattern of change in that variable across time. For these analyses the Mplus software was used.
Continuity and Change in Baseline ANS Measures
Baseline RSA. The repeated ANOVA comparing baseline RSA scores across the three time points was significant, F(2, 205) = 15.94, partial ( = .03, p < .01. The post hoc t-tests indicated that baseline RSA in kindergarten (M = 7.32, SD = .07) was significantly larger than baseline RSA in preschool (M = 7.15, SD = .08), p = .01. Baseline RSA in first grade (M = 7.37, SD= .07) was greater than baseline RSA in preschool, p < .01; but did not differ from baseline RSA in kindergarten, p = .43. Overall, these results suggest that there was a mean-level increase in baseline RSA from preschool to kindergarten, but not from kindergarten to first grade.
Given that the repeated-measures analyses indicated an overall increase in
children’s baseline RSA, a linear growth model was conducted to examine (a) the overall mean-level change in baseline RSA across time, and (b) to test whether there is between- individual variability in the intercept and slope. The fit of the linear growth model was acceptable, χ2(1) = 1.50, p = .22, CFI =1.00, RMSEA =.04 (.00-.17), SRMR = .02. As
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presented in Table 12, the unstandardized coefficient for the mean of the intercept was 7.22 (p < .001), suggesting that children showed moderate to high levels of baseline RSA in preschool. There was a significant and positive main effect for the slope (B =.09, p = .004), suggesting that on average, children’s baseline RSA increased over time. The variance of the intercept was significant (B = .92, p < .001), suggesting that there was between-individual variability in children’s baseline RSA scores in preschool. The variance of the slope was also significant (B = .11, p =.021), suggesting that children varied in how their baseline RSA scores changed from preschool to first grade.
Baseline PEP. The repeated ANOVA comparing baseline PEP scores across the three time points was significant, F(2, 168) = 16.05, partial ( = .09, p < .001. The post hoc t-tests indicated that baseline PEP in kindergarten (M = 92.52, SD = .51) was significantly larger than baseline RSA in preschool (M = 91.31, SD = .49), p = .01. Similarly, baseline PEP in first grade (M = 94.01, SD = .49) was larger than baseline PEP in kindergarten, p = .004. Overall, these results suggest that there was a mean-level increase in baseline PEP over time.
Given that the significant results from the repeated-measures analysis and paired- wise t-tests suggesting an overall increase in children’s baseline RSA, a linear growth model was conducted to examine (a) the overall mean-level change in baseline PEP across time, and (b) to test whether there is between-individual variability in the intercept and slope of baseline PEP. The unconditional linear growth model for baseline PEP yielded a negative variance for the slope, which is an impossible solution. One common approach for resolving this type of error is to constrain the variance of the slope to zero,
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which allows for 2 additional degrees of freedom (see Hinnant et al., 2017 for a similar finding). The fit of this model was good, χ2(3) = 1.31, p = .73, CFI =1.00, RMSEA =.00 (.00-.07), SRMR = .11. As presented in Table 12, the unstandardized coefficient for the mean of the intercept was 91.12 (p < .001), suggesting that children’s baseline PEP scores in preschool was significantly different from zero. The mean of the slope was positive and significant (B =1.29, p = .004), indicating that children’s baseline PEP scores showed an average increase of 1.29 per year during the study. The variance of the
intercept was significant (B = 24.09, p < .001), suggesting that there was significant variability in children’s baseline PEP scores in preschool. As indicated by the impossible negative variance in the slope of baseline PEP, there was no variability in the trajectories of baseline PEP across time.
Continuity and Change in RSA Responsivity Scores
The continuity and change in children’s RSA responsivity was examined for the two cognitive challenges, Tangrams and Go/No-Go, because they were conducted at each time point.
Tangrams. The repeated ANOVA comparing RSA responsivity during Tangrams across the three time points was not significant, F(2, 202) = .44, p < .64, suggesting that there was no change in children’s RSA responsivity during Tangrams across time.
Go/No-Go. The repeated ANOVA comparing RSA responsivity during Go/No- Go across the three time points was significant, F(2, 191) = 4.58, ( = .02, p = .01. Results from the paired t-tests indicated that there was no difference in RSA responsivity scores obtained in preschool, and in kindergarten, p = .48. However, RSA responsivity in
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first grade (M = .26, SD = .54) was significantly smaller than RSA responsivity in
kindergarten (M = .40, SD = .51), p = .003, and in preschool (M = .36, SD = .47), p = .03, suggesting that children experienced lower levels of RSA withdrawal in in first grade than in preschool and kindergarten.
Continuity and Change in PEP Responsivity Scores
The continuity and change in children’s PEP responsivity was examined only for Tangrams and Go/No-Go because these tasks were used across all time points.
Tangrams. The repeated ANOVA comparing PEP responsivity during Tangrams across the three time points was not significant, F(2, 145) = 12.73, p =.08, suggesting that there was no change in children’s Tangrams RSA responsivity scores across time.
Go/No-Go. The repeated ANOVA comparing PEP responsivity during Go/No-Go across the three time points was significant, F(2, 142) = 12.83, partial ( = .08, p < .001. RSA responsivity scores during Go/No-Go decreased from preschool (M = .27, SD = 2.36) to kindergarten (M = -.41, SD = 2.80), p = .02; but increased from kindergarten to first grade (M = 1.23, SD = 3.32), p < .01.
Goal 4. To Examine Whether There are Profiles of Children with Distinct Patterns