The study was performed in the after-school center of a primary school in a German city. A total of 50 children participated in the study and 45 of them performed both sessions. Four of them were excluded from analysis because of strong disturbances by incoming people or technical problems. Three children (aged 7, 8, and 9 years) were excluded based on insufficient performance (less than two standard deviations of the mean hit rate in the respective age group). The analysis included 38 children (16 aged 7 years, mean 7 years 5 months, 9 female; 10 children aged 8 years, mean 8 years, 3 months, 6 female; 12 aged 9–10 years, mean 9 years, 8 months, 3 female). Participation was rewarded by age-appropriate gifts and a certificate of participation. Children gave oral and parents gave written informed consent. Parents confirmed their children's normal hearing, normal or corrected-to-normal vision, no medication with effects on the nervous system, and no history of attention-related disorders. The project was approved by the local ethical committee of the Medical Faculty of the University.

We presented two versions of an auditory-visual oddball paradigm (Figure 1). The novel condition included uniquely presented novel environmental distractor sounds. The pitch-deviant condition included two different pitch-deviant distractor sounds. The two conditions were presented in a within-subject design on two separate days in order to keep the experimental time as short as possible. The mean interval between the two sessions was 6 days. Each condition included three blocks with 36 trials each. The order of conditions was balanced between subjects.

The environmental sounds presented in the novel condition were selected from a database described by Wetzel et al. (2011) and have been rated as identifiable sounds (Wetzel et al., 2011). Novels such as bird songs or sneezing were presented only once within a sequence of a repeated environmental standard sound (fragment of a bell). In contrast to some of the previous studies (e.g., Gumenyuk et al., 2001) we did not present novel sounds within a sequence of sine wave standard sounds in order to reduce the influence of differences in bandwidth and sound complexity between standard and distractor sounds. In the pitch-deviant condition, sine wave sounds with frequencies of 500 Hz (77.7%; standard) and 400 (11.1%) and 600 Hz (11.1%) were presented. All sounds had a duration of 500 ms including a raised cosine windowed fade-in and fade-out of 10 ms each. Sounds were presented with a loudness of average 53 dB(A), 55 db SPL. The loudness of sounds was equalized to 6.5 sone (DIN 45631 with diffuse field equalization, Zwicker et al., 1991).

Participants were asked to distinguish between two different target categories by button press and to ignore the sounds (Figure 1). The target categories differed between the three blocks: (1) princesses and knights (2) cats and chickens (3) butterflies and fish (Figure 1). Within each target category, two versions of the targets were presented slightly differing in shape and color, one oriented toward the left and the other toward the right side. That is, per block four possible targets from two categories (e.g., orange and green fish vs. yellow and purple butterflies) were presented with equal probability (25% each) in pseudo-randomized order. In order to maintain children's motivation and interest, the three blocks included not only different target objects but also a different appropriate background landscape. Princesses and knights were presented in front of a palace and a fortress, cats, and chickens were presented in front of a basket and a chicken roost in a village, and butterflies and fish were presented together with a flowering shrub and a pond embedded in a coastal landscape. Targets and background scenes were the same in the novel and pitch-deviant condition.

The children's task was to press the button that locally matches the preferred and habitual residence of the target object (Figure 1). Children were instructed to press the button as fast and correctly as possible. Correct button presses were rewarded while the target object walked, flew, or jumped to the preferred place. The short presentation of two feedback target stimuli caused the impression of the target objects' movement toward the preferred place. No feedback was given in the case of incorrect or missing responses.

The ability to concentrate was tested using the subtest “Selective Attention” of the Intelligence and Development Scales for children aged 5–10 (Grob et al., 2013). This paper and pencil test consists of several rows of ducks looking to the right or to the left. Children were asked to mark ducks looking to the right which have two orange features (e.g., two orange feet). Children were instructed to mark each row of ducks as quickly and correctly as possible within a certain time period. The raw value includes the number of processed ducks minus the number of wrongly omitted and wrongly marked ducks. The highest possible raw value was 225. Raw values can be transformed into “value points” ranging from 1 to 19 on the basis of age standards (value points 1–6 below-average, 7–13 average, 14–19 above-average).

In order to compare distraction by auditory stimuli with visual distraction, we used the subtest “The enchanted castle” of the standardized computer-based Test of Attentional Performance for Children (KiTAP version 1.5, Zimmermann et al., 2002). Children were asked to press a button if a sad ghost appeared and to not respond if a happy ghost appeared. A variety of visual distractor pictures such as witches or other night creatures were occasionally and randomly presented. Distractor sounds preceded the occurrence of ghosts and were presented within the time range that is usually needed for an eye saccade. The authors stated that if children were distracted by the surrounding non-targets they were not able to distinguish target and non-target ghosts. The test computed reaction times, correct, incorrect and omitted responses as well as age-related T-values and percentile ranks in trials with and without distractors.

The children were introduced by the teacher to the experimenter. The experimenter explained the “game.” Each of the three blocks was preceded by a training session in order to familiarize participants with the block-specific targets and backgrounds. The training was not limited in time and included two distractor sounds and six standard sounds. Novel sounds that had been presented in the training blocks were not presented in the experimental blocks. The training block was repeated in case more than 50% of trials were not correctly responded (only one child needed a repetition). The order of blocks was balanced. Distractor sounds were pseudo-randomly presented with a probability of 22.2% (8 per block). Each distractor sound was preceded by at least two standard sounds in order to enable the generation of an auditory regularity of standard sounds. The allocation of sound types to the following target category was balanced. The experimental trial duration was 3300 ms (Figure 1), block duration was about 2 min and the duration of the complete distraction paradigm was about 6 min without breaks. The standardized tests of concentration and visual attention were performed after the experimental task. Per session one of the two tests was performed. The order of tests was balanced. The distraction paradigm was presented using a MacBook (13.3″) via Matlab (The MathWorks, U.S.A.) and the Psychtoolbox (Kleiner et al., 2007). Sounds were presented via external loudspeakers (Bose Corporation, U.S.A) placed on the left and right of the notebook display. To collect responses, two large external response buttons placed on the left and the right side of the notebook were used. The response buttons were connected with an RTBox (Lee et al., 2012), wich provided accurate response time measurements.

The first and the second standard trial in a block as well as the first standard trial after a novel trial were removed from the analysis. A mixed-model analysis of variance (ANOVA) including the within-subject factors sound type (standard, distractor), condition (novel, pitch-deviant), and the between-subject factor age (7 years, 8 years, 9–10 years) was used to analyze mean reaction times, hit rates and omission error rates. In order to test the processing of novel and pitch-deviant sounds throughout the experiment, distractor-minus-standard difference values (distraction effects) were tested using an ANOVA with the factors condition (2), block order (first vs. second vs. third presented block), and age (3). To test relations between sound processing (reaction times, distraction effects) and the ability to concentrate (raw values), we performed a Pearson's correlation separately for conditions. To account for the additional influence of the factor age, a partial correlation was performed. We compared visual distraction effects measured using the standardized KiTap attention test with distraction effects measured using the experimental oddball paradigm. The partial correlation included the mean reaction time difference between trials with and without distractors (KiTap), the mean reaction time difference between distractor and standard trial (experimental oddball paradigm), and age. Our analysis is based on KiTap data that were corrected after the experiment by the editor of the KiTap since delayed response times were incorrectly classified in the original data. A probability p-value of less than 0.05 was considered as significant. Greenhouse-Geisser corrections were applied when appropriate. Follow-up t-tests were run for statistically significant interactions and were Bonferroni-corrected if necessary. All statistical analyses described above were performed using Matlab (The MathWorks, U.S.A) and SPSS (IBM, U.S.A.).

The ANOVA with the factors sound type (2) × condition (2) × age (3) revealed that distractor sounds prolonged reaction times in comparison to standard sounds [main effect sound type: F_{(1, 35)} = 44.34, p ≤ 0.001, η_p² = 0.56]. Reaction times in the novel condition were increased compared to reaction times in the pitch-deviant condition [main effect condition: F_{(1, 35)} = 6.65, p ≤ 0.014, η_p² = 0.16]. Distraction effects differed between groups [interaction of the factors sound type × age: F_{(2, 35)} = 3.82, p ≤ 0.031, η_p² = 0.18; see Figure 2]. Distractor-related impairments decreased with age [t-tests distractor vs. standard; Bonferroni correction applied: 7-year-old: t₍₁₅₎ = 5.42, p ≤ 0.001, 33 ms; 8-year-old: t₍₁₅₎ = 3.30, p ≤ 0.009, 26 ms; 9–10-year-old: t₍₁₁₎ = 3.65, p ≤ 0.004, 11 ms]. Importantly, novel sounds elicited prolonged reaction times compared to pitch-deviant sounds, whereas reaction times in standard trials did not differ between the conditions [interaction of the factors sound type × condition: F_{(1, 35)} = 8.06, p ≤ 0.007, η_p² = 0.19; t-test novel vs. pitch-deviant: t₍₃₇₎ = 3.21, p ≤ 0.003; t-test standards in the novel condition vs. standards in the pitch-deviant condition: t₍₃₇₎ = 1.06, p = 0.296]. The interaction including the factors condition × age was not statistically significant [F_{(2, 35)} = 1.38, p = 0.265, η_p² = 0.07]. The interaction including the factors sound type × condition × age was not statistically significant (F < 1). The main effect of age was not statistically significant [F_{(2, 35)} = 2.22, p = 0.123, η_p² = 0.11]. When including the factor gender (female, male) in the analysis, no gender-related effects were observed.

The hit rate ranged from 89 to 96% (Table 1). No statistically significant effects were found for the hit rate. Results revealed F-values < 1 except for the main effect of age [F_{(2, 35)} = 1.17, p = 0.322, η_p² = 0.06] and the three-way interaction [F_{(2, 35)} = 1.47, p = 0.244, η_p² = 0.08]. The omission rate was larger in the oldest group than in both younger groups [main effect age: F_{(2, 35)} = 5.824, p ≤ 0.007, η_p² = 0.25, Scheffé-test: 7 years vs. 9–10 years: p ≤ 0.029, 8 years vs. 9–10 years: p ≤ 0.014]. No further interactions or main effects were statistically significant (all F-values < 1.3).

To control for possible effects of target category (or background scene) and deviant pitch (high or low; pitch-deviant condition only) we computed separate ANOVAs on the distraction effect. Neither target category (main effect and interactions including target category F < 1) nor deviant pitch [RT: deviant type × group F_{(2, 35)} = 1.18, p = 0.319, η_p² = 0.063; main effect deviant type F_{(1, 35)} = 0.06, p = 0.802, η_p² = 0.002; hit rate: deviant type × group F_{(2, 35)} = 1.47, p = 0.244, η_p² = 0.077, main effect deviant type F_{(1, 35)} = 1.43, p = 0.239, η_p² = 0.039] significantly modulated the distraction effect.

In order to test the course of distraction as a function of practice, we compared RT distraction effects (distractor minus standard) in the novel and pitch-deviant conditions between blocks. The distraction effects of the youngest children significantly decreased from the first to the second presented block in the novel condition (Figure 3). This strong decrease was not observed for the pitch-deviant condition and not for the older children. The interaction of the factors condition × block order × age was statistically significant [F_{(4, 70)} = 3.94, p < 0.009, η_p² = 0.18, ε = 0.885]. The follow-up interaction of the factors condition × block order was statistically significant only in the youngest children [F_{(2, 30)} = 17.25, p ≤ 0.001, η_p² = 0.54, ε = 0.793; middle children F_{(2, 18)} = 1.41, p = 0.269, η_p² = 0.14, ε = 0.965; older children F < 1]. The follow-up t-test for the youngest children revealed larger distraction effects in the novel condition in the first block than in the second block [t₍₁₅₎ = 3.87, p ≤ .002] whereas distraction effects did not differ between the second and the third presented block [t₍₁₅₎ = −0.451, p = 0.659]. In contrast to the novel condition, distraction effects numerically increased throughout the experiment in the youngest children in the pitch-deviant condition, but these order effects missed statistical significance (first block vs. third block: t₍₁₅₎ = −1.965, p = 0.068; first block vs. second block: t₍₁₅₎ = −1.832, p = 0.087; second vs. third block: t₍₁₅₎ = −0.953, p = 0.356).

The number of mean value points in the IDS concentration test was 10. Twenty-eight (74%) children performed the IDS concentration test at average level (7–13 value points). Seven (18%) children performed at below-average level (4–6 value points). Three (8%) children performed at above-average level (14–19 value points). Children who performed better in the IDS concentration test (raw values) responded faster in distractor (r = −0.611, p ≤ 0.001) and standard trials (r = −0.568, p ≤ 0.001) in the pitch-deviant condition. The pattern of this relation was similar but less pronounced in the novel condition (novel: r = −0.315, p = 0.058; standard: (r = −0.381, p ≤ 0.020). No relation between distraction effects (distractor minus standard) and performance in the concentration test (raw values) was observed (novel condition: r = 0.087, p = 0.608; pitch-deviant condition: r = −0.255, p = 0.128). No statistical significant correlation between hit rate (all r < 0.213) or omission rate (all r < 0.145) and performance in the concentration test was observed.

Commission and omission error rate and median RT in the standardized visual distraction test of the KiTap revealed the following results (mean T = 50, one standard deviation = 10). Commission errors: 17 (45%) children scored T < 40, 19 (50%) children scored T-values between 40 and 60, and two (5%) children scored T > 60. Omission errors: eight (21%) children scored T < 40, 17 (45%) children scored T-values between 40 and 60, 13 (34%) children scored T > 60, median RT: 21 (55%) children scored T-values between 40 and 60, 17 (45%) children scored T > 60. The analysis of the KiTap mean RT, commission and omission errors using an ANOVA with the factors distractors (trials including visual distractors vs. trials without visual distractors) and age (3) revealed no statistically significant interactions (all F < 1.1). Reaction times were 26 ms faster in go-trials including visual distractors compared with go-trials including no distractors, but this result revealed no statistical significance [481 ms vs. 507; F_{(1, 35)} = 3.32, p = 0.077, η_p² = 0.087]. The number of commission errors showed a tendency to increase in trials including distractors [10 vs. 9; F_{(1, 35)} = 3.27, p = 0.079, η_p² = 0.085]. No age effects were observed (all F < 1.5). Visual distraction effects measured by mean reaction times and commission errors in trials with and without distractors (KiTap) did not correlate with distraction effects in the experimental oddball paradigm (novel condition: r = −0.199, p = 0.298; pitch-deviant condition: r = 0.176, p = 0.296).

Distraction effects have been observed in all age groups in the present auditory-visual oddball task. This means that reaction times were prolonged when visual targets were preceded by a distractor sound in relation to targets that were preceded by a standard sound. In fact, 37 out of 38 children showed a behavioral distraction effect in response to novel or pitch-deviant sounds. Importantly, the effects of task-irrelevant sound processing on performance decreased with age, i.e., the distractor-related performance was more impaired in younger than in older children. Results confirm our hypothesis and indicate a significant development of attentional control during the age of 7–10 years.

Most important, the analysis of distraction effects as a function of practice throughout the experiment revealed considerable age differences. In the novel condition, we observed distraction effects of 116 ms in the first presented block in the youngest children (Figure 3). This distraction effect significantly declined after the first block (by 97 ms). Distraction effects did not significantly differ between the second and the third block (19 vs. 26 ms). Both groups of older children also showed a numerical a decline of distraction effects from the first to the second block in the novel condition, but this decrease was considerably smaller (by 23 ms, Figure 3). In the literature, slight decreases of effects of novelty from the first to the forth block have been also observed in adults when presenting an auditory oddball stimulation including sounds and words while participants performed a visual task (Parmentier, 2008). On the basis of our results, we hypothesize that age effects on distraction by novel sounds are composed of several factors. One factor is the basic level of distraction that is assumed to differ between age groups independent of the block order. Distraction effects in the final block decrease with age, but it cannot be excluded that distraction effects would have declined further if more blocks had been presented. A future study including more blocks could investigate when exactly distraction effects reach a plateau in several age groups. The magnitude of the distraction effect in the second and third presented blocks indicates that the proportion of basic age differences might be smaller than assumed previously. In contrast, experience seems to play a critical role for the magnitude of distraction in the different age groups. It can be hypothesized that younger children initially evaluate a number of task-irrelevant novel sounds in detail causing the increased distraction effects in the first block. In contrast, older children were able to control distraction by novel sounds more successfully at an early stage of the experiment. They potentially are able to categorize novel sounds as task-irrelevant and prevent detailed evaluation despite the novelty of sounds. Another explanation could be that pitch-deviant sounds were repeated during the experiment causing habituation of the orienting of attention. However, since novels were never repeated during the experiment, the repetition hypothesis cannot completely explain the abrupt decline of distraction effects in the novel condition. Furthermore, the results of a similar auditory-visual oddball study by Berti (2012) do not support this hypothesis. Berti observed comparable distraction effects in adults in response to uniquely and repeatedly presented environmental oddball sounds. The repetition hypothesis can also not explain the slight increase of distraction effects as a function of practice in both groups of younger children (Figure 3). Our results support the assumption of different developmental time courses of control of attention in the context of novel environmental and pitch-deviant sounds that should be considered in future research.

The age effects on behavioral distraction reported in the present study are in line with research on the development of the underlying brain mechanisms. The occurrence of a sound that differs from the predicted model that has been built up on the basis of the regularities in the acoustic environment, can cause attention to be oriented toward the new sound and its evaluation. Orienting and distractor evaluation mechanisms have been associated with the event-related potential (ERP) P3a or noveltyP3 in the EEG (for review see, Escera et al., 2000; Friedman et al., 2001; Polich, 2007). ERP-studies with children that focused on the ability to control involuntary orienting mechanisms reflected by the P3a reported immature control. When children aged 6–8, 10–12 and adults were asked to attend sound duration within an oddball paradigm, unexpected and task-irrelevant changes in pitch caused orienting of attention and deviant evaluation in all age groups (reflected by P3a, Wetzel et al., 2006). When participants were asked to ignore the same sound sequence and to focus attention on a video clip, then children, in particular the youngest children, nevertheless showed a P3a component, indicating involuntary orienting of attention toward pitch changes. In contrast, adults did not show a P3a when instructed to ignore sounds, indicating successful control of attention orienting. Similar results were observed in an oddball study presenting environmental distractor sounds to 9–10-year-old children (Wetzel, 2015). Also 13-year-old children were more impaired by distractor stimuli in a visual-spatial working memory task than adults (Olesen et al., 2007). The fMRI study reported that children showed stronger activity in the superior frontal sulcus in response to distractor stimuli, which was not observed in adults. The authors discuss that this may explain children's increased susceptibility to distractor stimuli (Olesen et al., 2007).

We observed no effects of sound type, condition, or age on the hit rate or the omission rate. The mean hit rate was 93% indicating that children can easily cope with the task. In the literature, one study reported age effects on the distractor-related hit rate (Gumenyuk et al., 2004), while others did not (Gumenyuk et al., 2001; Ruhnau et al., 2010, 2013). The level of task performance might affect novel related effects on the hit rate. It cannot be excluded that distractor-related impairments of accuracy might be observed if the task were more difficult. However, since we focused on reaction time effects, we decided to present an easy task in order to maintain children's motivation across the two sessions.

In summary, our results specify the developmental time course of distraction by unexpected and task-irrelevant sounds during the age of 7–10 years. The ability to shield against distraction by unexpected and task-irrelevant sounds undergoes significant maturation in middle childhood and increases with age.

Reaction times differed in distractor but not in standard trials between the conditions. Novel environmental sounds elicited larger reaction time prolongation than pitch-deviant sounds (Figure 2). The increased distraction potential of novel environmental compared with pitch-deviant sounds is in line with ERP-studies comparing the effects of these sounds on P3a or noveltyP3. In an auditory-visual oddball study with participants aged 6–18 years, novel environmental sounds elicited increased orienting and distractor evaluation mechanisms reflected by increased P3a amplitudes compared with pitch-deviant sounds (Wetzel and Schröger, 2007a). This result has been replicated in a group of 5–12-years-old children by (Brinkman and Stauder, 2008). Similar pattern of results was observed in adults (e.g., Alho et al., 1998; Gaeta et al., 2003; Berti, 2012). Results of the present study confirm our hypothesis that postulated that novel sounds have a higher distraction potential resulting in increased impairments in a task at hand. The higher distraction potential can be caused by several features differing between novel and pitch-deviant sounds such as complexity, meaning, and novelty. Environmental sounds have a complex structure since they contain a variety of frequencies, whereas pitch-deviant sounds contain only a single frequency. Even infants processed physically complex oddball sounds (e.g., bursts of noise) differently from pitch-deviant sounds (Wetzel et al., 2016). In their auditory-visual oddball study, the distractor-related pupil dilation response was clearly increased in response to noise oddball sounds (that included a variety of frequencies), whereas no response was observed in response to pitch-deviant sine wave sounds (included a single frequency). Furthermore, in contrast to the pitch-deviants, novel environmental sounds provided a meaning that can affect control of attention. It has been reported that the sound of the one's own smartphone captures more attention than the sounds of other smartphones when presented in an oddball paradigm to adults (Roye et al., 2007). Even infants responded to oddball sounds, that provided an emotional meaning (e.g., the cry of a peer), with increased pupil dilation than in response to a phone ring which had a similar complexity but a probably less significant meaning (Wetzel et al., 2016). Semantic information therefore might increase the personal significance of novel sounds contributing to differences between the conditions. A further important difference is the novelty of the distractor sounds. Novel sounds were presented only once and were indeed new in the experimental setting. In contrast, the two pitch-deviants were repeated several times. It has been reported in adults that the processing of novel and pitch-deviant sound activates partly different neural networks (e.g., Escera et al., 1998). The authors suggested that different brain mechanisms involved in change detection were triggered by the different types of sounds. There is some evidence for the auditory modality indicating that even newborns differently process deviancy and contextual novelty and that this separation continues to develop beyond the first year of life (Kushnerenko et al., 2013). It can be assumed that this development also continues into the school-age years since pitch-deviant sounds as well as novel sounds caused prolonged reaction times in children in the present study, whereas in a similar adult study, only novel sounds caused reaction time prolongations (pitch-deviants caused reduced hit rates in adults, Escera et al., 1998, for similar RT effects see also Berti, 2012). The assumption of an ongoing development of the underlying processes is supported by the opposite course of novel- and pitch-deviant-related distraction effects throughout the session in the 7-year-olds.

Our alternative hypothesis of decreased distraction effects in response to novel sounds was not confirmed by the data. This hypothesis was based on adult studies that reported a facilitated processing of targets preceded by novel compared with repeated deviant sounds (SanMiguel et al., 2010; Wetzel et al., 2012). It has been discussed that distraction effects include both, the costs of the orienting of attention away from task-relevant features as well as the benefits of an increase of arousal in response to novel sounds (Näätänen, 1992). The distraction effects could be affected by attentional focusing induced by the task and temporal links between the distractor and target (SanMiguel et al., 2010). In a study focusing on involuntary attention in typically developed children and children suffering from ADHD (8–13 years), novel sounds improved performance in an Eriksen flanker task in both groups of children (Tegelbeckers et al., 2016). The authors did not present an oddball design, but rather presented equiprobably task-irrelevant repeated standard sounds, novel sounds, or silence. The hit rate of the typically developed children was rather similar to those of our study indicating a similar level of task-difficulty. It can be assumed that either the features of the task or the presented frequency of the novel sounds modulate performance. This assumption is supported by findings of a study that investigated typically developed children and children with ADHD (8–12 years) and used a similar design as in the present novel condition (van Mourik et al., 2007). The authors reported prolonged reaction times but reduced error rates in response to novel sounds. Children with ADHD significantly reduced errors of omission after the presentation of a novel sound. This has been discussed in the context of an increase of arousal to an optimal level (van Mourik et al., 2007). However, under the present experimental conditions, no facilitated processing of novel sounds compared with pitch-deviant sounds were observed in children, indicating that the costs of orienting outbalanced any potential benefits of facilitated novel processing.

In summary, larger distraction effects in response to novel environmental sounds than to pitch-deviant sound have been observed in 7–10-year-old children. Future studies are required in order to disentangle which of the sound features discussed above or which combination of sound features contribute to the different distraction effects.

The ability to concentrate inversely correlates with reaction times in standard and novel trials. This indicates that children with an increased ability to concentrate responded faster to the visual targets or vice-versa. The less pronounced relation between the speed of responses in novel trials (relative to pitch-deviant trials) and the ability to concentrate might be caused by a broader variability of response times in the novel condition. This supports the assumption of partly different processing of novel and pitch-deviant sounds. The authors of the IDS concentration test depicted that the concentration test measures basic cognitive functions such as to memorizing target features, focusing attention on target features, inhibiting of distractor features, sustaining attention as well as the flexibility to apply several rules. Similar cognitive abilities were required in order to successfully perform the experimental distraction task. Therefore, we expected that performances in the concentration test and experimental distraction task would correlate with each other to a certain degree. However, our statistical analysis revealed no relation between distraction effects and the ability to concentrate. On the one hand, this could indicate that the mechanisms underlying the processing of distractor sounds are not directly related to the ability to concentrate. One reason could be that the concentration test requires cognitive functions that exclusively gain input from the visual modality. In contrast, the experimental distraction task requires cross-modally operating mechanisms that might require cognitive abilities that are not reflected in the performance on the concentration test. If this assumption is true, then additional cross-modal concentrations tests should be used to measure selective attention abilities in children. Since distraction in every-day life often occurs in cross-modal situations, this would be a more ecologically valid measurement. On the other hand, it is possible that children performed too homogeneously in the standardized concentration test. Our study focused on healthy children. Children with attention problems, that often show impaired performance in concentration tests, did not participate in this study.

In the standardized visual distraction test (KiTap), children tended to respond faster and less correctly to targets in the condition that included visual distractor stimuli. Results could be caused by an accuracy-speed trade off. A study that tested the construct validity of this subtest of the KiTap in a similar age range reported a reverse pattern: increased reaction times and reduced commission errors in the distractor condition (Schöneck et al., 2014). However, the authors also discussed that the results might have been caused by an accuracy-speed trade off. We observed no relation between the distractor-related performance in the visual distraction test and the distraction effects elicited by the auditory distractors in the experimental task. This result supports the statement by Gomes et al. (2000) who emphasized that the (advanced) knowledge on the development of visual attention cannot be simply assigned to the research on the development of auditory attention. The present study revealed distinct distraction effects that were sensitive to the type of the eliciting sound and that differed between age groups—emphasizing the need of developmental attention research in the auditory modality. The integration of both fields of attention research can contribute to the development of general models of attention and can enhance knowledge of the developmental time course of attention. Moreover, the present paradigm was not only sensitive to attentional control abilities but was also suitable for children since it was less time consuming, playful and most of the children enjoyed participating. Therefore, similar paradigms might be useful in order to investigate typically developed children including preschool children as well as atypically developed children including children suffering from attention disorders.

The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.