Figure 1.
Inter-session reliability of time-on-task slope.
Time-on-task slope is significantly correlated across two test sessions spaced one week apart (ICC1,1 = .54, p<.01). Subjects show a tendency to perform slightly worse in the second session.
Table 1.
Paired t-tests comparing subjective states before and after PVT performance.
Table 2.
Factor analysis (with varimax rotation) of the change in subjective variables from pre- to post-task.
Table 3.
Allele counts and frequencies.
Figure 2.
Average time-on-task slope by allele group.
Means and standard errors for reciprocal reaction time slope in each allele group. * represents p<.05. Yellow bars represent allele groups thought to have greater dopamine availability.
Figure 3.
Average reaction time curves by allele group for DAT1 and COMT.
Curves were plotted using predicted values calculated from average parameters A, T1 and T2 for each allele group. The thinner dotted curves represent the mean ± one standard error. Note that the curvature of the trends is only slight despite the use of an exponential equation; this is due to the bimodality of T1, for which large values cause the curve to approach linearity. Panel A: COMT allele groups. Panel B: DAT1 allele groups.
Table 4.
Univariate ANCOVA of the effects of dopamine alleles on RRT slope.
Table 5.
Univariate ANCOVA of the effects of dopamine alleles on exponential time-on-task parameters.
Figure 4.
Average subjective change in energy by allele group.
Means and standard errors for average subjective energy change in each allele group. * represents p<.05. Yellow bars represent allele groups thought to have greater dopamine availability.
Table 6.
Univariate ANCOVA of the effects of dopamine alleles on subjective change in energy.