Anne Fleur Kortekaas-Rijlaarsdam

CHAPTER 6 124 Table 6.2 Group characteristics of the ADHD and TD group ADHD (N=63) TD (N=67) ADHD v TD Percentage boys ( N ) 68.25 (43) 59.70 (40) χ 2 =1.03 M SD M SD Age 10.49 1.24 10.16 1.32 t =-1.43 Estimated IQ 97.68 13.82 106.10 12.93 t =3.45** DBD parents Inattention 17.46 4.40 3.78 2.98 t =-20.86** Hyperactivity/Impulsivity 13.21 5.32 3.06 2.75 t =-13.78** ODD 7.21 4.28 CD 1.68 2.43 DBD teacher Inattention 16.40 4.88 Hyperactivity/Impulsivity 11.89 6.91 ODD 4.92 4.82 CD 1.14 2.24 DISC parents Inattention 7.83 1.16 Hyperactivity/Impulsivity 6.22 2.40 ODD 2.95 2.29 CD 0.46 1.08 Note . ADHD Attention-deficit hyperactivity disorder; TD Typically developing controls; DBD Disruptive Behavior Disorder rating scale; DISC Diagnostic Interview Schedule for Children, ODD Oppositional defiant disorder; CD Conduct disorder; U = Mann-Whitney U-test statistic **p<.01 Task Validation GLMM analysis showed a condition effect in the TD group ( t (66)=2.18, p =.033, d =.16) for achieved difficulty level: With positive feedback, the achieved math level was .39 higher (on a scale of 1-12). In addition, the results from our paired sample t-tests showed that, on average, TD children improved during the math task with performance at the end of the task being significantly better than at task entry, for both conditions ( t (66)=2.40, p =.019, d =29 and t (66)=4.71, p <.001, d =57 for the neutral and the motivation condition, respectively). Furthermore, both entry level and achieved math level show a strong correlation to scores on a math automatization task that is frequently used in school settings and scientific research (Speeded Arithmetic Test, De Vos, 1992) ( r =.72, p <.001 and r =73, p <.001 for entry level and achieved math level, respectively).