One game per child
There is no such thing as an “average” child with autism. Each child manifests unique strengths and skill deficits. Things that are reinforcing or rewarding to one individual may be unpleasant for another person . Any play activity must therefore be oriented to addressing the unique capability and needs of each individual child, which implies that a game must support a high degree of customizability. It must enable caregivers to adapt a gaming experience to the individual skills and preferences of each child, such as modifying multimedia contents, rewards, play time, body movements.
To support the evolving needs of a child over time, the game should support increasing levels of motor and cognitive complexity of game tasks , enabling the progression along a continuum of game sessions involving activities that are similar but more and more demanding in terms of motor, cognitive and social skills required.
Within a play session, children should have a unique, explicit, well focused game goal to reach (e.g. “hit as many moving objects as possible”, “avoid as many falling asteroids as possible”). The goal should be associated to one single task and a clear set of movements the child can afford (e.g. move arms to hit objects) to promote the development of goal oriented motor actions (the cognitive process of organizing movements to achieve a given goal)
Understanding the game goal and tasks should be promoted before playing and should be reinforced during the whole game session. Children, especially those with a delay in or a total lack of verbal language, can benefit from visual means for communication, like PCSs (Picture Communication Symbols) and iconic images representing the movements to be performed and the body parts to be used.
After a good performance, offering a rewarding stimulus which is “valued” or “liked” by the child increases motivation, enhance player’s engagement and implicitly improve her skills . In our experience, medium-low functioning autistic children might not value much as rewards quantitative performance results (e.g., points or extra time won). What seems to act as a stronger motivator and a positive reinforcement is a video or audio effect that creates fun, e.g., the play of cartoon videos, funny animations, cheerful music, and applauses. In case of scarce game performance, these elements should not be necessarily removed at all, but can be reduced and completed with something that fosters children to do better, e.g., visual instructions, in order to help managing frustration’s issues.
Repeatability and Predictability
Autism appears to have a well-established affinity with interactive technologies. Repeatability plays an important role to achieve mastery and provide control of the rate of learning. Repeating the same routines (tasks) improves not only individuals’ mastery but also gives the predictability they need as well as clear expectations of the next future.
The same game is typically played many times in the same configuration. Eventually, the child will need to move from a level in which she has proved to be successful to the next one, which unlocks new challenges and opportunities. It must be very easy for the caregiver and the child to repeat a game, or to move to the “next level”. The time of restarting a session or switching from one level to the next one must be minimized, to reduce the risk of a child’s loss of concentration during the transition.
Visual items should be cheerful and aesthetically nice, but always strictly functional to the goal. Children may be distracted from visual elements that are not strictly relevant for the current task and lose attention. In addition, too many visual stimuli may induce anxiety as children may not be able to discriminate and interpret single elements within a group. Graphic elements should have clearly distinguishable shapes and should not overlap. For some children, the use of colors may need to be reduced. Some subjects, for example, can work with black and white images only, and get very nervous when dealing with other colors.
Sound or music can be used not only to provide feedbacks on actions. They should be played during moments when nothing happens on the screen or there is a transition from one game configuration to another, or at the end of the game to complement visual rewards effects. At the same time, it is important to remember that autistic children easily reach a point in which too many audio stimuli are perceived just as a mass of noise that they cannot interpret and creates extra stress. Hence similar principles mentioned for visual elements (see “Minimalistic Graphics”) apply to sound: Sound elements should be cheerful, clear, simple, and functional to the game task and to the need of keeping children’s attention.
Dynamic stimuli such as animations and music should be provided along the entire game session. When visual elements remain static and nothing else happens, the child may lose concentration and move her attention to something outside the game. Even worse, a prolonged static situation may trigger abnormal behaviors, such as stereotyped movements or motor rigidity (e.g. motionless gazing the static image on the screen), which typically must be “unlocked” by a caregiver’s intervention.
In any game activity, enjoyment increases when visual or audio effects create wonder or surprise. This is also true, at some degree, for autistic children. Hence sensory stimuli should balance phenomena that are more predictable consistently with the ongoing task (e.g., audio feedbacks on child’s movements) with serendipitous effects (e.g., a new different object appears and disappear on the screen), but always having in mind the risk of attention loss.
Avatar is the virtual representation of the child inside the game that offers an immediate visual feedback to a player’s actions. It enforces the perception of “self” ( “It looks like me!” – a child during our experiments). The game space becomes like a “virtual mirror” where the player sees herself, establishes a connection between her movements and system’s reaction , and develops imitative abilities (see also Guideline “Developing imitative abilities” in sect 3.3). In addition, avatars can be a means to direct children’s focus of attention on the effects of their movements rather than the body movements per se, to promote static and dynamic motor skills (see General Guideline “Motor control through “external” attention”). Hence avatars should be incorporated in a game even when they are not strictly functional to the game narrative structure, e.g., they do not represent characters of a “story”.
We identified three different kinds of Avatars:
- Articulated Avatar: all part of body are represented using simple shapes (points, lines, circles…) and follow players’ movements
- Pointing Avatar: user is represented by a single image that follows the movements of only one part of the user body.
- Real Avatar: user is shown using the mask defined by his body outline (silhouette), eventually integrated with the image of child coming from color camera.
Motor control through “external” attention
To promote static and dynamic motor skills (i.e., movement control, balance, or postural control) it is important to provide audio-visual stimuli associated to each movements or still position needed to perform a game task, in order to direct children’s focus of attention on the effects of his movements rather than the body movement per se. This guideline is grounded on a number of studies pinpoint that fostering “external” attention focus (on the effects of one’s movements) rather than on the movement itself (“internal” attention focus) can boost motor learning.  found an increase in motor performance when directing an individual’s attention “externally” compared to directing attention “internally”. The advantage of focusing attention on the movement effect might be that it allows unconscious or automatic processes to control the movements required to achieve this effect. When persons focus on their body they might be more likely to consciously intervene in these control processes and may inadvertently disrupt the coordination of a number of relatively automatic (reflexive and self-organizing) processes that normally control the movement. Although there is no reported study exploring these phenomena with autistic children, observations in our evaluation activities confirm the above results.
Increasing gross motor skills
Gross motor skills enable such functions as walking, jumping, kicking, sitting upright, lifting, throwing, as well as head control, trunk stability, maintaining balance, balancing position from one foot to the other . To promote the development of these skills, interaction can comprise the actions above and in general, movements that involve the large muscle groups and the whole body. As motor skills generally develop from the center to the body outward and head to tail, the progression of tasks (see General Guideline “Evolving Task”) should include a progression of movements initially involving the whole body and then increasingly more peripheral parts.
Increasing postural stability
To promote postural balance and control, the game can involve tasks that require to maintain still positions (e.g., keeping head or arms steady), to keep the line of gravity of the body with minimal sway, to balance position from one foot to the other. Task complexity can be increased by requiring alternating dynamic movements and static gestures, or progressively augmenting the time during which motion-less positions must be maintained (offering appropriate rewards as time proceeds).
Various types of tasks can promote motor coordination :
- Tasks that involve coordinated movement of different parts of the body, or eye-rest of the body coordination. For example, to hit a virtual object, still or moving, in different positions or with varying speed, the child can use legs and arms alternation, shift of left and right arm or leg, or the combination of both arms.
- Tasks that require distinguishing left/right or forward/backward, determining the distance between objects, combining movements into a controlled sequence, remembering the next movement in a sequence
- Tasks that require to apply visuo-spatial memory, which concerns to perception of spatial relationships among objects (e.g., in jigsaw puzzles) and is thought to be associated to coordination deficits.
Promoting perceptual learning and attention skills
Perceptual learning forms important foundations of complex cognitive processes (i.e., language) and is defined as “the process of learning improved ability to respond to the environment” . These improvements range from simple sensory discriminations – focusing on, and discriminating between, certain stimuli – to identification of items as belonging to the same or different category, to complex categorizations of spatial and temporal patterns relevant to real-world expertise. Perceptual learning is widely seen as tightly coupled with various forms of attention: sustained attention – the ability to direct and focus cognitive activity on specific stimuli; selective attention – the process by which a person can selectively pick out one message from a mixture of messages occurring simultaneously; weighted attention, which entails making a distinction between relevant and irrelevant stimuli. Different types of tasks and visual contents can promote perceptual learning:
- Tasks that require the child to stabilize his gaze and track with his body moving objects on display (sustained attention)
- Tasks that require moving the entire body or some body parts to hit or avoid specific moving objects (sustained attention).
- Tasks that involve movements to express simple sensory discriminations, e.g., distinguishing colors, shapes, sizes, position of objects (selective attention)
- Task that require to recognize a visual shape among multiple shapes or to reproduce a similar shape with the body (a body position (selective attention)
- Tasks and visual contents that require the child to focus on similarities or on differences such as pointing to and gripping visual elements representing different food types or the same food type (selective attention)
- Tasks that involve more complex categorizations of spatial and temporal properties of the objects on display in situations relevant to a child’s own life, e.g., “What do you eat at breakfast? Grasp only the food you eat at breakfast”) (weighted attention)
- Tasks that require the child to select information relevant for a task, and ignore irrelevant information, e.g., among various falling objects, hitting only “target” elements (weighted attention)
Increasing space awareness
Space awareness can be increased identified by tasks that involve moving in and out a constrained space (e.g., defined by a circle drawn on the floor) or rotating the body to change perspective on a virtual 3D space on the screen.
Increasing body awareness
To increase awareness of body and body structure, multimedia contents and movements should emphasize the identification of body parts, how they work and how they fit together. For example:
- Playing songs that focus on body parts, such as head, shoulders, knees and toes, and ask the child (while singing) to touch the parts of the body in the song, or to move and shake them (clapping, stopping and head nodding)
- Involving more than one child and requiring children doing interactions while certain body parts are touching the whole time, such as hands, elbows or heads, proving feedbacks when a player disconnects (see also Guideline “Engaging in human-human interaction”)
Developing imitative capability
Autistic children show limited imitative capability, which is manifested by the lack of spontaneous make-believe play or social imitative play . The (realistic or schematized) shape of the player’s body and her movements in the game virtual space are fundamental to promote the development of imitative skills (see also General Guideline “Avateering”). Other means are the inclusion of tasks like the following ones: imitating the movements of characters on display; forming static shapes using the body that correspond to shapes or images on display; performing gross and fine motor movements that animate characters on the screen (objects, animals, vegetables, humans), e.g., in a storytelling contexts; imitating the movements of co-players (adults or peers).
Not Only Multiplayer
Most touchless games can be developed for being played by both a single individual and two or more persons without changing game logic. However, moving together in front of a display and performing independent or complementary tasks do not necessarily triggers social interaction. This is especially true for autistic children  who do not engage with others spontaneously. Social interaction must be supported “by design”, with multiplayer tasks that are explicitly conceived to promote and exert social skills (see next guidelines).
Motivating Human-Human Interaction
The game should include tasks that require movements of more than one player to be completed, i.e., jumping together to overcome an obstacle, creating a body shape that simulates a character on the screen with 3 legs and 4 arms. Visual elements and rewards should emphasize the concept of “together” and acknowledge the benefits of doing things cooperatively. Also avatars can act as a social cue that may influences children’s perceptions leading them to perceive the experience as more ‘‘social’’.
Children with ASD often are self-absorbed and seem to exist in a private world where they are unable to successfully communicate with others. It is important to give them a motivation to make the effort of sending and receiving messages. To this end, a task that requires players to give verbal and non-verbal mutual instructions to reach a goal (e.g., “while I move here you have move there”) offers a motivating opportunity for communication.
Increasing joint attention
Joint attention is the intentionally shared focus and interest of two individuals on the same object or event. It is achieved for example when one individual alerts another to an object by means of eye-gazing, pointing, or other verbal or non-verbal indications, and the other person looks back to her after looking at the object. Joint attention abilities are important for many aspects of language development, socio-emotional development and the ability to take part in normal relationships, and are negatively affected by autism. To support joint attention it is important to include tasks where one or more of the situations below take place:
- one child has to call the attention of another child, or an adult, toward a target objects, e.g., through a pointing gesture
- two children have to coordinate each other in order to find a target object and catch it simultaneously
- two children have to alternate in the same or different tasks (“turn taking” ) and regulate one’s behavior to the one of the co-player