Mediation criteria for interactive serious games aimed at improving learning in children with attention deficit hyperactivity disorder (ADHD)

The PASS intelligence theory (Planning, Attention-Arousal, Simultaneous and Successive) was used together with Feuerstein’s mediation model to develop a system of categories for mediation in educational games. This system was used to analyze and improve the design of interactive games that can enhance mediation in learning, particularly in children with attention deficit hyperactivity disorder (ADHD). To this end, interactive games designed for a tabletop device were evaluated within an educational context. 27 children (3–14 years old), who had been diagnosed with ADHD, took part. The tabletop has an intuitive system that allows children to interact directly with objects with which they are familiar, providing opportunities for play and communication. These games were evaluated by the participant observation of individual and group playing experiences, interviews, and two focus groups. The results show that mediation recommendations can be useful in the design of the games. They also confirm the need to improve the adaptability of the games to enable children with ADHD to mediate, plan, and focus their attention. With the aid of a facilitator, the mediating function of learning-games can therefore be applied in the development of the executive functions that are key to learning.


Introduction
Attention deficit hyperactivity disorder (ADHD) is one of the most frequently diagnosed neurodevelopment disorders in childhood, with a prevalence of around 5% in Spain (Graham et al., 2011) and 10% in the USA (Akinbami, Liu, Pastor, & Reuben, 2011). It is characterized by a high degree of inattentiveness, hyperactivity, and impulsiveness, according to Barkley (2015), The Diagnostic and Statistical Manual of Mental Disorders (DSM5) (APA. American Psychiatric Association, 2014) and The International Statistical Classification of Diseases and Related Health Problems (ICD10) (MSSSI, 2016). This disorder can have very serious effects on children's lives (Harpin, 2005). Children with ADHD can have difficulties developing mathematical (Cragg & Gilmore, 2014;Iseman & Naglieri, 2011) and language (Kuijper, Hartman, Bogaerds-Hazenberg, & Hendriks, 2017) skills and in general with academic learning (Dietz & Montague, 2006). Social skills can also be affected (Barkley, 2015). Comorbidity is another frequent issue in that many children with ADHD also suffer from dyslexia, tic disorders, and Tourette's (Spencer, Biederman, & Mick, 2007). ADHD can also appear alongside autistic spectrum disorder and sufferers may lack empathy.
Attention deficit hyperactivity disorder from the perspective of the PASS theory of intelligence In school, this can often lead to academic failure and even exclusion experiences, especially, if ADHD is comorbid with conduct problems. ADHD children often need more attention and care both at school and at home, where their condition can lead to stress and tension within the family (Harpin, 2005). For this reason, some children with ADHD receive support in school, such as behavioral interventions, adapted teaching methods, and home-school communication programs (DuPaul, Weyandt, & Janusis, 2011).
The problems these children face at school have been attributed to weakness in their executive functions resulting in inattention, disorganization, and impulsiveness or lack of planning, which make problem-solving difficult (Barkley, 2015). Current research confirms that cognitive dysfunctions in attention and planning processes are strong predictors of ADHD (Das & Misra, 2015). In a similar vein, studies based on the PASS theory of intelligence (Das, 2018) indicate that people with ADHD find it very hard to pay attention to relevant stimuli and to inhibit incorrect answers and have a great difficulty formulating and supervising plans and strategies (Canivez & Gaboury, 2016).
The PASS theory of intelligence explains cognition through three systems (planning, attention-arousal, codification). Codification (simultaneous and successive processing) and planning interact to coordinate and facilitate knowledge acquisition. However, these superior functions depend on us paying attention to enable learning to take place. Base knowledge and mediation modulate the way we use them (Das, Naglieri, & Kirby, 1994). Therefore, effective processing of the information we receive requires the interaction of base knowledge, planning, attention-arousal, and codification. The task we are being asked to do must also be taken account (Das, 2018;Mahapatra, 2016) (Fig. 1).
Planning is a mental process that allows us to identify, select, and solve problems in an effective way (Das, 2018). It requires awareness, motivation, and meta-cognitive skills. Effective planning therefore requires active strategic cognition and behavior. Attention helps us to maintain arousal levels and ensures that we focus exclusively on the relevant stimuli, ignoring all irrelevant or extraneous input. The planning system is responsible for controlling and organizing, for executing plans and strategies, and for monitoring our actions and taking decisions (Mahapatra, 2016) There is also a strong link between codification and planning, as tasks can be codified in different ways; the implementation of simultaneous and/or successive processing is influenced by the executive functions and the earlier learning experiences of the person (Das, 2018;Mahapatra, 2016;Walker, 2010).
According to PASS theory, if children have attention problems are disorganized and show impulsive behavior (ADHD), the planning process must be taken into account when evaluating their needs and attending to them. Working with these children to help improve their selective attention, strategic behavior and metacognitive knowledge will help them inhibit an inappropriate level of excitement. It will also facilitate the activation of strategic action plans and allow them to self-regulate and thereby solve their attention problems. Improving self-control must therefore be a priority. Das's conceptual definition (1998, page 58) of planning as "a self-organized and reflective process of which the person is aware... and which requires motivation and metacognitive capacities" captures the importance of the "planning process" in educational intervention with ADHD children.
The PASS theory also covers the emotional processes that emerge from learning. The meaning that children confer on success and failure experiences can influence their motivation (Rosenthal & Jacobson, 1968). It also stresses the importance of making the implicit explicit, as this helps children with structuring and planning, key aspects of selfcontrol. This process of self-awareness turns interaction into a source of learning. The purpose of mediation must therefore be to enable children to make decisions, reflect on them, discover different alternatives, and share them. To this end, attention and planning processes must be strengthened by means of intervention, interaction, and dialog.

Mediation as a facilitator of learning
Mediated learning (Feuerstein et al., 2006;Feuerstein & Feuerstein, 1991;Vygotski, 1996) is a sociocultural approach to learning that seeks to understand human beings in  Das (2018, 13) a broad context. For learning to become a mediated learning experience, and for this learning to have an effect on the child's cognitive system, the interaction must have a special quality. This helps produce a higher level of modifiability in children. Feuerstein et al. (2006) proposes 11 categories for the mediation described in Table 1.
Interaction and mediation are key issues in improving cognitive and motivational processes, in that they can generate learning (Amod, Heafield, & Seabi, 2018;Chan et al., 2017). In mediated learning, internalization and self-regulation are of crucial importance because students must be active, conscious, independent, and creative. Mediation is a process in which the mediator guides and provides support to other people to enable them to learn. This support is built inductively, through dialog, experimentation, and argumentation.
By interacting with the learners, the mediator (also referred to as the facilitator) creates opportunities to produce and choose the most appropriate cognitive planning strategies, in this way, encouraging a more abstract level of thought, so promoting the process of change in an experiential way. Dialog helps to define problems and to compare and discover new possibilities, which means that social interaction is crucial in supporting learning (Farrell Frey, Iwa, & Mikroyannidis, 2017;Sulisworo, Agustin, & Sudarmiyati, 2016). It can improve planning and attention processes, ensure correct understanding, and expand or enlarge meaning and motivation (Garrido, 2004). Feuerstein refers to this kind of interaction, with an impact on motivation, as "mediation." This process induces a feeling of change known as "cognitive modifiability" (Feuerstein et al., 2006), a concept associated with the "zone of proximal development" proposed by Vygotski (1996). Interaction and mediation are key factors in the mediated learning experience model (MLE), which is structured around eleven parameters: intentionality and reciprocity, mediation of transcendence, mediation of meaning, feeling of competence, reflective practice, interdependency and sharing, individual esteem, goal seeking and achieving, challenge of novelty, change awareness, and the search for optimistic alternatives (Feuerstein & Feuerstein, 1991;Oon Tan, 2003;Tzuriel, 2013). Games are a privileged context in which educators can act as mediators, inviting children to explore and generate questions that can enhance planning and attention abilities. In this sense, interactive games can be incentives for learning (Mayer, 2015) and can mediate to improve attention, planning, and self-regulation.

Interactive games and ADHD
Games are essays for real life and offer a natural way to stimulate different cognitive processes. Games link abstract thinking with specific experiences, so allowing children to try out what they have learnt, putting their newly acquired knowledge into practice without the fear of being wrong (Paris & Winograd, 2003). In this way, games can contribute to teaching strategies and the development of teacher mediation practices (Jong, Dong, & Luk, 2017) Children with ADHD show interest in competitive sports and games and in those that involve movement, intense activity, and frequent changes, as they normally prefer quick answers and short interventions (Colombo et al., 2017). However, they can also have social skill deficits that make peer relationships difficult (Marton, Wiener, Rogers, Moore, & Tannock, 2009), leading them to reject games that entail cooperation and linguistic abilities (Young & Gudjonsson, 2006).
To stimulate motivation and commitment to the task (Geurts, Luman, & Van Meel, 2008), it is important to understand how interactive games enhance the learning process. They strengthen experiential autonomous learning (Fokides, Chronopoulou, & Kaimara, 2019;Pina & Bordonaba-Juste, 2018) and allow learners to implement their knowledge-building skills (Piñeiro-Otero & Costa-Sánchez, 2015). Videogames encourage learning and can help improve academic performance (Harley, Poitras, Jarrell, Duffy, & Lajoie, 2016), especially in children with experience of academic failure, a frequent issue for ADHD sufferers (Karande, Mahajan, & Kulkarni, 2009). Videogames interact with the players and provide them with information through images and sounds, so boosting multisensory representation of knowledge. An attractive design is therefore a key factor in the quality of any activity aimed at children (Crescenzi-Lanna & Grané Oro, 2016) and in order for these games to achieve positive results and impacts, it is important to take into account how the contents are presented, which perceptive and cognitive abilities are put into practice and in what way the social and affective skills are enhanced (Connolly, Boyle, MacArthur, Hainey, & Boyle, 2012).
In this study, we analyze the benefits of tangible interactive games in which physical objects are handled on a table with an active surface, the NIKVision Tabletop (Cerezo et al., 2019). The interfaces have physical form enabling children to perceive and touch the different elements of the games (De la Guía, Lozano, & Penichet, 2015). The tabletop also has an internal projector that projects images and animated films on to the surface, which then become part of the game, in combination with auditory stimuli (Fig. 2). Games can be played either individually or in groups. The physical appearance of the tabletop is very similar to that of a standard table. The interaction is carried out by moving physical objects over the surface. Direct handling of the objects reinforces the motivational impact of the games (Read & Markopoulos, 2013).

Research questions
The purpose of this study was to evaluate the function of tabletops as mediators in the learning process of children diagnosed with ADHD. The study analyzed the qualitative data to assess the function of tabletops as mediators from a perspective based on PASS theory and Feuerstein's model of mediation. Three questions guided the study: -Do the interactive games developed for the tabletop enhance the mediation process in learning, as proposed by Feuerstein? -How must the games be designed to provide children with ADHD with mediation functions in the learning process? -Which kinds of mediation could be included in interactive games to promote the attention and planning processes (PASS theory) in children with ADHD?

Objectives
The current paper aims, firstly, to analyze various tabletop games on the basis of the mediation learning experience model, as a way of assessing the suitability of interactive games for the development of planning and attention processes in children with ADHD. Secondly, it attempts to design a mediation guidance model within which to develop interactive games that improve attention and planning (PASS theory). Feuerstein's mediation functions are included in the design of the software and in the work of the mediator/facilitator.

Research design
A case study was carried out using qualitative methodologies (Flick, 2008;Merrian, 2009), in order to understand the meaning of the different interactive and communicative processes in real life (Kaplan & Maxwell, 2005). Specifically, formative research (Frick & Reigeluth, 1999) analyzes and evaluates ways of improving the design of games to favor mediation aimed at enhancing attention and planning processes in children with ADHD.

Learning environments
In this study, the children interacted in person with the Nikvision tabletop ( Fig. 2) with 4 kinds of games (riddles, memory, mazes, and stories).
These games included a range of different activities, each with different levels. In the games with mazes for example, the children have to reach a place on the map, overcoming various challenges (riddles and letter-word order problems) (Fig. 3)  way. In memory games (Fig. 4), the children have to remember and describe a picture they have previously been shown, and in letter-word order problems, they have to arrange letters or words in such a way as to form meaningful words or phrases. For its part, the stories activity involves reading or listening to a story and then answering comprehension questions about it (Fig. 5). The games have different levels to cater for the different age groups and to create new challenges (Figs. 3 and 4).

Participants
The participants are children from an association of families with ADHD children.
The educators at this association provide extracurricular educational support to ADHD children with learning or social difficulties. Twenty-seven children from this association, aged between 3 and 14 years old took part in the study. Of these, 1 was 3 years old, 12 were between 6 and 8 years old, 8 were between 9 and 11 years old, and 6 were between 12 and 14 years old. 19 of these children had been diagnosed with ADHD, of whom 9 had associated behavior problems. Six children had been diagnosed with ADD, one with autism (ASD) and one with ADD and mild intellectual disability. Their educator accompanied and observed the children during the play sessions. Before the study began, the families of the children gave informed consent for their children to participate in 3-h observation sessions (from 17:00 to 20:00) over the course of 3 months, as part of the study.

Data collection
The method used to collect the data was participant observation (Kawulich, 2005;Spradley, 1980). The data was collected with three different tools or methods at various stages of the process (Table 2). Firstly, four researchers observed the children at play, taking specific notes in the field diary in relation to technical aspects of the operation and programming of the game, and regarding the relationships, mediation processes, and dynamics established amongst the participants. All incidents or problems were documented. The researchers acted merely as observers and did not interfere with the dynamics of the children and the educators.
Secondly, two interdisciplinary discussion groups were organized. The first focus group was held in the middle of the study. The following participants took part:  Two researchers organized and led the discussion group.
Participants discussed the benefits of the game in terms of improving learning, cognitive processes, and commitment.
an education expert, a computer engineer, and three educators from the ADHD association. The second focus group, held at the end of the study, was made up of four members of the first focus group (an education expert, a computer engineer, and two educators from the ADHD association) plus two new experts in this field. One was an educator from the ADHD association and the other was a psychologist. As a result, a total of 8 people took part in the two focus groups, in which they discussed the progress made by the children during the sessions, exploring above all the following issues: To what extent the guidance offered by the game helped the children: -To understand the game and actively take part in it.
-To understand the context of the game.
-To ask themselves if they had done it well or why they had acted in one way or another. -To feel that they had taken the right decisions after analyzing other options with regard to possible consequences and degree of satisfaction.
-To express their ideas and support them with arguments.
-To create new strategies and adapt to new challenges.
-To work at different levels of abstraction.
-To enhance commitment to the task.
Finally, interviews were conducted with three of the educators, who were asked open questions about the support required to enhance the children's attention and help them plan their actions during the games. The educators offered their professional opinions regarding the children's participation in the games and as to whether the activities had functioned as expected (Brinkmann & Kvale, 2014). In the open interviews, the educators were asked about how the children had behaved when interacting with the game, both spontaneously and when prompted by the suggestions offered by the game and by the facilitator. They were also asked why and when it was necessary for a mediator to intervene to ensure that children learned. The interviews were carried out at the educational center at times when the educators were not with the children. The interviews lasted about half an hour each.

Procedure
The children were observed playing four tabletop games (riddles, memories, mazes, and stories) that had previously been designed for workshops or activities with children (Fig. 6). These games were included as part of the extracurricular activities carried out at the ADHD association. The children played with the activities on the tabletop for 10-15 min with the support of educators at the end of each session. Twelve of them played individually with the tabletop, while the other fifteen played in groups of three or four, respecting the dynamic of the previous session. The researchers offered support to the children and collected information about the games and the children's response to them. This support was only provided when the children were unable to solve the game for themselves. This support involved asking questions to encourage them to reflect and to search for alternative strategies to solve the game, in this way improving their attention and planning skills. The computer engineers monitored the games to make sure that everything was working correctly.
Through participant observation, the researchers assessed the mediation processes, the relationship between the participants, and the interaction between the players and the game. As far as possible, the researchers tried to improve the games in line with the educators' recommendations and the children's comments. The interviews and the first discussion group were very useful for improving the games, in that they provided a means of assessing the mediation processes on the basis of the perceptions of both educators and children, so applying a user-centered methodology for enhancing game design (Powell, Parker, & Harpin, 2017).
The data collected in relation to the interaction and mediation processes was categorized according to the parameters of MLE, based on references from the literature (Feuerstein & Feuerstein, 1991;Oon Tan, 2003;Tzuriel, 2013). Participant observation was carried out considering the relevant criteria for children with ADHD, and from a global perspective, in order to enable our results to be applied to any interactive game. Later, in a second interdisciplinary discussion group, the researchers and educators discussed the possibilities of the game for improving mediation-for-learning processes. So as to ensure the credibility and honesty of the procedure, the researchers shared the transcriptions of the interviews and focus groups with the participants as well as the results of the research (Guba & Lincoln, 1982). This validation by the respondents not only enhanced the credibility of the procedure, but also helped improve the design of the tabletop. The credibility of the qualitative study also benefited from the triangulation process involving the sources of information, the tools used, and an interdisciplinary team of researchers.

Results
The results stem from a systematic thematic analysis (Braun & Clarke, 2012) based on the parameters characterizing mediated learning experience (Feuerstein et al., 2006;Feuerstein & Feuerstein, 1991) and PASS theory (Das, 2018). In this analysis, we searched for structures and meanings, which were then organized into categories. This involved a deductive categorization process based on a systematic, iterative data analysis, in line with previous scientific studies. This analysis allowed us to build meanings from the data and make sense of commonalities. After analyzing the data in relation to mediated learning, we proposed recommendations for the eleven mediation parameters that should be considered in the design of interactive games, so as to ensure that these games can mediate in the learning process (Table 3), in which the facilitator also takes part (Coma, 2015). In this way, we tried to incorporate the mediation guidelines into the structure and design of the games. Table  3 shows the types of mediation that most influence the attention or planning processes, although as the PASS model makes clear, these functional units are interconnected.
The results show how adjustments to the games can encourage mediation. Reciprocity, transcendence, and feeling of competence were the categories most involved in the attention process, according to the researchers' analysis of the data in relation to mediated learning.
As regards reciprocity (M1), we noticed that children engaged best when it was easy for them to understand what they had to do. For example, one of the educators explained in an interview that "I found it very useful to be able to go back and reread the instruction when a child did not remember what they had to do" (interview, educator 1) (Figs. 7 and 8). Similarly, children may achieve most when the game is flexible and adapts to their needs: "We noticed that when children read an instruction themselves, they generally understood it better. We therefore asked the game's designer to include an option allowing the children to choose between reading or listening to the instructions" (focus group 2, educator 4) (Fig. 8). As regards transcendence (M2), the games need to facilitate attention to the important elements, with the aid of the educators. Educator 2 (interview) explained it like this: "Sometimes, children respond to riddles they know, but there are other riddles that they don't understand, and I have to help them by explaining the context behind the play on words?".
At the beginning of the study, one of the educators suggested that "The games should have different degrees or levels of activity" (Field diary). We therefore added different levels to the game to encourage a feeling of competence. After this, the same educator offered some interesting feedback in a focus group discussion: "The mazes were very dynamic and visual. The children worked very well (…). They were responsible for managing the pace of the game" (focus group 1, E4) (Fig. 9). In this way, when children were playing the game, they made decisions and tried out different options. Successful completion of the game allowed children to feel responsible for achieving their goals, so developing a feeling of competence (M4). They can also learn from their mistakes by going back to try different options to help them achieve their goals. As educator 1 explained in an interview: "When they fail, we can encourage them to try and try again." The categories most closely related to planning are meaning, regulation of behavior, sharing, psychological differentiation, goal seeking and achieving, challenge of novelty, change awareness, and the search for optimistic alternatives.
Initially, the system did not generate questions about the decisions the children had taken (Why did you choose A rather than B?). This job was left to the facilitator, so minimizing the trial-and-error thought process. As educator 6 said in focus group 2: "They put the toy down randomly on the different options on the table without trying to figure out which was the best one." If the game system generates the right questions, it can encourage children to be more aware of their actions and their thoughts-mediation of meaning (M3). If not, the facilitator stops the game to ask the children why they took a certain decision. As educator 5 explained in focus group 1: "We have to stop the game and ask the child why he/she has taken that decision, to make them think." With these pauses, educators mediate in reflective practice, activating strategies for reflection in decision-making (Psychological differentiation, M7).
In the first game sessions, the facilitator was unable to control the pace of the game to give the children time to plan. "We wanted to stop the game to allow the children to think, but it was impossible" (interview, E3). The game was then modified after which educator 5 remarked (focus group 1): "After you added the option to stop, we were able to enhance thinking and planning" (Fig. 8). The option to stop the game enabled the children to successfully complete the various tasks after explaining the reasons for their decisions (Regulation of behavior, M5). Playing in groups forced the children to take their peers' opinions into account (Interdependency and Sharing -M6-, and Individual esteem). As one of the computer engineers explained, "when children played in pairs, they had to reach a prior consensus before deciding which answer to choose" (discussion group, CE 1).
Children think more and perform tasks better when they receive references that allow them to plan. Educator 6 (focus group 2) explained this as follows: "Children do not always attribute the same meaning to words as we do. Speech balloons with instructions would help them know exactly what to do." The guidance provided by the educators is necessary for active goal seeking and achieving (M8), as the education expert commented: "(…) in general, the children activate planning, but adult support is needed" (focus group 1, EE). Motivation increased after the game incorporated challenges of novelty (M9) because these involved new planning strategies and reinforced commitment to the task. Educator 3 found that "adding more levels encouraged most of the children to keep moving forward. One girl even verbalized the fact that she did not like the first level because it was too simple" (Interview, E3).
In the comprehension activities, the children read or listen to a story. They are then shown various images and must find the relationship between the images and the story (Fig. 8). This requires a higher level of abstraction. In this way, games can facilitate structural change (M10), although they need the support of the educators. As educator 4 said: "He needs the support of the mediator to associate concepts" (focus group 2, E4).
Technological feedback was added to let the child know if they had selected the correct option and to encourage them to continue with the task (Fig. 9). In the interview, educator 1 told us that "The children like to receive verbal or gestural confirmation. We need to include "smiley faces" or an icon to let them know whether they are right or wrong". In this way, games can help them search for optimistic alternatives (interview, E1) (M11).
In Tables 4 and 5, the recommendations are classified according to whether they have more influence on the attention process or the planning process. They also specify which recommendations require the involvement of a mediator, as technologically speaking it is not always easy to adjust the game to the characteristics of the participants and their learning process.
As can be seen in the table, in those recommendations in which the mediator has an important role, it is because his or her goal is to ensure that the child clearly understands how to solve the task and has the chance to look for new alternatives that adapt well to the new situation, in this way developing flexibility and cognitive modifiability.

Learning process
Previous research has shown that adults, young people, and children are motivated by serious games (Girard, Ecalle, & Magnan, 2013;Mayer, 2016), which can be effective tools for developing our cognitive skills (De la Guía et al., 2015;Jackson, Brummel, Pollet, & Greer, 2013;Nguyen, Gardner, & Sheridan, 2018). To achieve learning goals, games have to be planned to balance learning and fun (Lameras et al., 2017). Within the framework of PASS theory, planning involves executive functions and is necessary for controlling and organizing behavior and making decisions (Georgiou & Das, 2014). It is therefore essential to take mediation criteria into account in the design of activities from an interdisciplinary perspective that ensures a preventive, stimulating intervention (Mahapatra, 2016;Paris & Paris, 2001).
According to Connolly et al. (2012), Harley et al. (2016), and Starcic, Cotic, and Zajc (2013), interactive games can improve attention processes and planning, especially in children with ADHD (Muñoz, Lopez, Lopez, & Lopez, 2015). In a systematic review, Powell et al. (2017) showed how serious games may also improve social skills and educational outcomes in ADHD children. If mediation criteria are taken into account in the design of these games, they could play an important role as a complement to learning and in the development of cognitive abilities (Amod et al., 2018;Girard et al., 2013).

Mediation guidelines
Guidelines have proved useful for defining and describing the kind of mediation that could take place in games and offer a new range of possibilities to be applied in game design that will be verified in future investigations. The findings show different effects on the attention and planning processes. In accordance with the findings of previous studies, game design must consider diversity, age group characteristics, and different mental approaches to learning and their cultural referents (M.1) (Asiry, Shen, & Calder, 2015;Mayer, 2016). Games must have graphics and elements with a clear meaning.
People need to understand these elements to be able to play the game (Starks, 2014).
The games have to mediate in reciprocity and allow the necessary adjustments to maintain a feeling of competence (M.3.) (Fokides et al., 2019;Lameras et al., 2017;Russell, Amod, & Rosenthal, 2008), and autonomy and meaning (M.4.) (Kulpa, 2017). Emotional feedback in real time encourages learning (Chan et al., 2017) especially if the feedback is customized and instantaneous (M.11.) (Argasiński & Wȩgrzyn, 2018 (Fessakis, Gouli, & Mavroudi, 2013). Because children have different abilities and needs, games should be flexible and adapted to help them face new challenges (M.9) (Nguyen et al., 2018). Some mediation categories have been detected through the difficulties in the game process. The players need to be aware of the rules of the game (M.4.). Regulation of behavior (M.5) should be taken into account by designers to improve cognitive and affective skills (Argasiński & Wȩgrzyn, 2018), especially for children with ADHD (Bul et al., 2015;Prins et al., 2013). To enable them to focus their attention, players with ADHD need to apply strategies and to separate relevant tasks from non-relevant tasks while playing (M.8.) (Van Sande, Segers, & Verhoeven, 2015). Mediation and oral interaction strategies (M.6) can facilitate the selection and building of strategies to improve learning and increase the levels of learning engagement. Furthermore, interaction and explicit metacognition can strengthen hypothesis generation and shared decisionmaking between players (Falloon & Khoo, 2014) and the ability to consider another person's viewpoint develops self-awareness (M.7) (Frith & Metzinger, 2016). As Frith (2012) argues, discussion with others enables us to go beyond our own beliefs and thoughts, to considerer new perspectives at a higher level of abstraction (M.10). This opens great challenges regarding the possibilities of mediation in games and emphasizes its importance. As Niemi and Multisilta (2016) point out, mediation skills are important for those acting in a digital environment.

Conclusions
It is important to promote attention and metacognition processes in children with ADHD. Mediation, interaction, and dialog encourage these processes and decisionmaking. Our results indicate that games can be adjusted and improved to encourage the mediation process, using the mediation guidelines. Serious games can mediate to enhance attention, planning, and self-regulation, especially in ADHD children.
The facilitators also play a very important role by mediating between the children and the games. This is a great responsibility in that they are offering support and recommendations for learning. Designers should bear in mind the features required to make games attractive and to facilitate planning, explicit metacognition, and the feeling of competence. Children's interests and prior knowledge must also be considered. Proposals are required in which both the technology and the facilitators encourage those taking part in the game to verbalize their thought processes so that the learning may be significant (Jong et al., 2017;Wouters, van Nimwegen, van Oostendorp, & van der Spek, 2013) and so that they can become aware of the importance of the decisions they are taking.
As regards the limitations of this study, it may be necessary to carry out the research over a longer period and with a larger sample group in order to find out whether following these recommendations in serious games enhances attention and planning processes.
It is necessary to continue with this line of research and develop new serious interactive games with these characteristics. This will enable us to evaluate the application of mediation criteria and their influence on learning and the development of cognitive and motivational skills (especially attention and planning) over a long period of time, combining qualitative research with pre-and post-test quasi-experimental assessment.