Participants

Forty-nine healthy, right-handed participants from three age groups (7-year-olds, 11-year-olds, and adults) participated in the study. All participants were without history of neurologic/psychiatric disorders, developmental disorders of scholastic skills, or Attention Deficit Hyperactivity Disorder (ADHD). Letters were distributed to the parents of children in the first and fifth grades of several primary and secondary schools in Frankfurt (Germany) in order to recruit 7- and 11-year-olds. Participants of the adult sample were students of Goethe University Frankfurt. 11 children of the youngest group were removed from the sample because they either failed to complete the study (3 subjects) or because of excessive movement (8 subjects; see section on “fMRI Data Analysis” below for exclusion criteria). Two children of the older group were removed because of incomplete fMRI data. The final sample consisted of 35 participants: 12 7-year-old children (6 females; mean age: 7.4, range: 6.5–8.0), 11 11-year-old children (5 females; mean age: 11.5, range: 11.1–12.0), and 12 adults (6 females; mean age: 24.7, range: 21.4–34.1). This sample size was determined based on several considerations, including the moderate to strong effect sizes obtained in our previous behavioral study (Wolf and Pfeiffer, 2014), the fact that the object tracking paradigm generally elicits robust BOLD activation in attentional networks (e.g., Culham et al., 1998; Howe et al., 2009), but also the potential strain of the fMRI session for the youngest age group. Adults received monetary compensation or course credit for participation. Children received a gift token and a certificate of participation, and parents received monetary compensation for travel costs. The study was conducted in compliance with the Declaration of Helsinki and was approved by the Medical Ethics Committee of the University Hospital Frankfurt am Main. All participants or their parents gave written informed consent prior to testing.

Children and adults participated in a separate behavioral testing session before scanning. Right-handedness was assessed by the Edinburgh Handedness Inventory (Oldfield, 1971) and visual acuity of at least 20/20 was ensured by a visual acuity test with a standardized Landolt C eye chart (Schairer Ophthal-Technik, Stuttgart, Germany). Participants were screened for psychiatric conditions by using the Strengths and Difficulties Questionnaire (SDQ; Goodman, 1997) for the children samples and the Symptom Checklist-90-Revised (SCL-90-R; Franke, 2002) for the adult sample. Children were additionally rated for symptoms of ADHD by their parents on the ADHD subscale of a test for diagnosis of mental disorders in children and adolescents (DISYPS-KJ; Döpfner and Lehmkuhl, 2003). All participants had scores within ± 1 SD of the mean of a normative sample in the respective tests. IQ scores were estimated by using Raven’s Standard Progressive Matrices (SPM; Horn, 2009) for children and Standard Progressive Matrices-Plus (SPM-Plus; Raven et al., 2000) for adults. Mean IQ scores were 108 for 7-year-olds (SD: 11.05), 101 for 11-year-olds (SD: 14.22), and 108 for adults [SD: 11.65; F(2,37) = 1.67, p = 0.20].