Table 1. Mean Scores (Standard Deviations) of age, clinical interviews, WISC-III, PPVT, Theory of Mind task, n-back task, Stop task per Participant Group.
| ASD (n = 46) a | ADHD (n = 37) a | TD (n = 38) a | Group differences (Bonferroni corrected post hoc analyses) | ||||
|---|---|---|---|---|---|---|---|
| M | (SD) | M | (SD) | M | (SD) | ||
| % Male | 87 | 84 | 66 | ||||
| Age | 9;3 | (1;10) | 8;9 | (1;7) | 9;0 | (1;9) | n.s. |
| ADI-R b Social Interaction | 16.46 | (6.19) | 4.51 | (4.07) | 1.82 | (3.09) | ASD***>ADHD>TD* |
| ADI-R b Communication | 12.72 | (4.57) | 3.97 | (2.66) | 1.42 | (1.80) | ASD***>ADHD>TD** |
| ADI-R b Stereotyped Behavior | 4.39 | (2.56) | 1.41 | (1.53) | 0.32 | (0.66) | ASD***>ADHD>TD* |
| ADI-R b Behavior < 3 yrs. | 2.98 | (0.98) | 1.49 | (1.52) | 0.13 | (0.41) | ASD***>ADHD>TD*** |
| ADOS c Communication | 2.78 | (1.51) | 1.06 | (0.92) | 0.53 | (0.76) | ASD***>ADHD, TD |
| ADOS c Social interaction | 7.44 | (3.22) | 2.67 | (2.01) | 1.50 | (1.72) | ASD***>ADHD, TD |
| ADOS c Com+Soc | 10.22 | (4.36) | 3.72 | (2.56) | 2.03 | (1.99) | ASD***>ADHD, TD |
| ADOS RRB | 1.22 | (1.36) | 0.28 | (0.57) | 0.16 | (0.44) | ASD***>ADHD, TD |
| ADOS Social Affect | 9.09 | (4.37) | 2.94 | (2.43) | 1.74 | (2.02) | ASD***>ADHD, TD |
| ADOS SA+RRB | 10.31 | (5.00) | 3.22 | (2.43) | 1.89 | (2.15) | ASD***>ADHD, TD |
| PICS d Inattention | 2.35 | (2.06) | 3.54 | (2.19) | 0.11 | (0.39) | ADHD**>ASD>TD*** |
| PICS d Hyperactivity/impulsivity | 2.04 | (1.99) | 5.11 | (2.51) | 0.29 | (0.57) | ADHD***>ASD>TD*** |
| WISC-III Block Design | 9.85 | (3.68) | 8.35 | (2.98) | 11.16 | (3.23) | ADHD<TD** |
| WISC-III Vocabulary | 8.65 | (3.34) | 9.49 | (2.09) | 11.82 | (2.51) | ASD***, ADHD**<TD |
| WISC-III Estimated IQ | 95.45 | (18.73) | 93.44 | (12.67) | 109.02 | (13.64) | ASD, ADHD<TD*** |
| PPVT WBQ | 104.09 | (15.27) | 100.22 | (12.49) | 108.84 | (10.72) | ADHD<TD* |
| Theory of Mind Task (Proportion correct FB1) | 0.87 | (0.21) | 0.87 | (0.14) | 0.94 | (0.11) | n.s. |
| Theory of Mind Task (Proportion correct FB2) | 0.55 | (0.40) | 0.56 | (0.34) | 0.78 | (0.29) | ASD, ADHD<TD* |
| N-Back Task (Numbers correct 2-back) | 38.95 | (8.13) | 38.19 | (7.45) | 41.77 | (5.28) | n.s. |
| Stop-Signal Task (SSRT) | 259.64 | (98.09) | 254.84 | (94.25) | 256.74 | (77.59) | n.s. |
* = p < .05;
** = p < .01;
*** = p < .001;
n.s. = non-significant.
a Number of participants may vary per task, since some children did not finish all tasks (see Procedure).
b Five children in the ADHD group scored on the ADI-R above the cut-off for ASD (on the basis of Risi et al.’s criteria [40]).
c Two children in the ADHD group scored above the ADOS criteria for ASD.
d Seven children in the ASD group scored within our criteria for ADHD on the PICS (above or one point below the cut-off on the PICS).