Twin A displays asynchrony in attention, behavior, and motor tonus, and her behavior lacks any coherent build-up of arousal or anticipation (Figure 2). The attempt at play with Twin A lacks structured phrases or a narrative arc - it is not a game at all. Twin A's behavioral style does not promote or modulate, in her father, the typical impulse to engage with graceful rhythmicity. Already (remember the twins are only 11 months old, way in advance of diagnosis, with the parents retrospectively reporting no concerns) the father has tacitly and completely adapted his interaction style. Wanting, naturally, to make his daughter happy, the father has dropped all attempts at social build-up with Twin A reverting, instead, to frequent moments of purely physical stimulation (the "monster belly blow"). Sadly, this natural adaptation will likely perpetuate asynchrony and asocial behavior in Twin A as she develops. The father, like many parents and practitioners, needed encouragement and therapeutic tools with which to tailor specialized attempts to connect with his daughter with autism.
Support for social timing should facilitate perceptual discrimination, timing, and contiguity of sensory input (for instance, reducing audio "noise" and latency). It should facilitate the temporal integration of multimodal information for just-ahead-in-time motor planning, and the just-ahead-in-time prediction of an other's communicative acts. It should facilitate the rhythm and phrasing of play. It should facilitate alignment of the movement/sound patterns of client and practitioner into good enough synchrony. Co-regulatory SMS should include a wide range of synchronous experience and involve a variety of narrative arcs in which partners travel together through different types and levels of arousal and back to calm.
Social timing and reciprocity are by no means seamless in TD infant interaction. Playful partners flow in and out of levels of synchrony. Sometimes partners share Simultaneity15, (traveling alongside each other, directly in-sync), experiencing concurrent occurrences of specific behaviors in parent and child, such as the co-occurrence of social gaze, vocalizing together, the matching of arousal level, or the coordination of parent affectionate touch with infant social gaze. Sometimes partners share Complementarity (the behavior of one partner complimenting the other's in timing and quality, while relating to the same pulse). In complementarity, behaviors often coalesce into repetitive "configurations", creating early rhythmic structures with inherent temporal expectations; expectations which can then be challenged and extended in playful teasing-around-timing (e.g., peepbo" vs. "pee....p-bo!" vs. "pe-ee........p-bo!"). This is particularly a feature of more sophisticated (bidirectional) mutual synchrony whereby each partner shares a more influential role. Such playful reciprocal "double-take" of expectations, during preverbal play with, and without objects, may facilitate appreciation of the "double meanings" required for symbolic play. Sometimes, partners are out of sync. found that infants regularly experience interactive miscoordination, yet mismatch is typically repaired close-on-instantaneously (review:). "This constant oscillation between momentary miscoordination and interactive repair marks the essence of human dialogue, to which infants are sensitized in their earliest interactions" (, p. 341) It is, in part, through the developing ability to recover synchrony when it goes off track, that TD infants may learn robust, flexible socio-communicative skills. For people with Autism(Therapeutic Needs), of course, the initial priority is enabling good-enough synchrony and helping to repair it where needed.
People with Autism(Therapeutic Needs) experience pervasive sensory disruption and fracturing. When this experience is acute, most often accompanied by heightened arousal levels, interaction is unfeasible. As practitioners we can help with a structured environment: minimal and consistent across all sessions; clean; low light levels; low levels of ambient sound; minimize smells; private (no disturbances); unconditional opportunities for time-out and rest. Long-term consistency of practitioner is also essential. A period of acclimatization may be a crucial precursor to potential playful interaction. In this period, practitioners should prioritize client-led sensitivity; sensitively mirroring while adding nothing; maintaining low levels of arousal; observing the client's needs, including the need for short-duration engagement, time-out and rest. As practitioners, we can be sensitive to when trust and simplicity become established - and feel carefully for those moments when our tentative input becomes feasible rather than damaging.
 helped children with autism gain improved fine motor control of their hand movements. They used a co-adaptive child-computer interface (visuo-spatial and auditory) to augment each child's spontaneous movement experience and substitute corrupted kinesthetic information. The aim was to give existing heterogenous movement patterns a chance, seeing these patterns as meaningful adaptations with personal momentum and rhythmicity. The study (and the trust) worked. "... This new concept demonstrates that individuals with autism do have spontaneous sensory-motor adaptive capabilities. When led to their self-discovery, these patterns of spontaneous behavioral variability (SBV) morph into more predictive and reliable intentional actions. These can unlock and enhance exploratory behavior and autonomy in the individual with autism."
Infants with Autism(Therapeutic Needs) often appear to channel the potential momentum of social engagement into interactions with the non-human environment. Disconnected from interaction, the infant's rhythmicity often appears in loops of repetitive behavior: movements and/or sounds [often referred to colloquially as "stimming" ]; relational patterns; or configurations of object-play. The loop is a self-completing pattern, with impulse and energy within either the beat pattern of repetitive movement or sound, or the discrete behavioral steps in a section of object-play. Each beat/step is essential to the pulse of the loop, to its momentum and sense of completeness. If present, we, as practitioner, can piggy-back on that pulse. If looping regularity is not apparent, we can find ways of integrating a pulse and moving from there.
In musical experience16, the presence of a beat enables the perception of rhythm and compels movement. Why is this?
Pre-motor organization engages a network of cortical regions [pre-motor cortex, supplementary motor area (SMA), and pre-SMA], which loop information via critical subcortical bodies (including the basal ganglia, brainstem and cerebellum), and route information through the IPL.
The SMA, basal ganglia, and the cerebellum comprise an, "extended cortico-subcortico-cortical functional network providing specific timing and entrainment sensitivities" (, p. 156), in the processing of auditory rhythm - the beat perception/generation network. Biological oscillators in these respective regions provide overlapping yet different time-signature ranges, and therefore differing functions, which complement each other in the full creation of rhythmic experience.
This beat perception/generation network shares significant structural and functional overlap with the pre-motor organization network. Oscillatory function within the pre-SMA, the SMA, and the basal ganglia in particular is integral to both beat generation and pre-motor organization. The basal ganglia and the pre-SMA/SMA are richly connected through striato-thalamo-cortical loops and are involved in the prospective timing of future movements. "A role for the basal ganglia and SMAs in beat induction is consistent with their involvement in motor prediction (the spontaneous response to hearing a beat is often to move at the time when the next beat is predicted)" (, p. 902).
The potential for beat-based SMS facilitation relies, of course, on intact beat-perception. Across simple and complex meter conditions, pre-SMA, basal ganglia, and cerebellar dysfunction in autism appears to be functionally specific, leaving beat-perception largely intact. The anatomically and functionally specific nature of basal ganglia dysfunction in particular may likely allow for a window of beat-based support.
 presented moments of potential prediction error (when a sound occurred earlier than expected in a regular series) to individuals with ASD (recruited via a multi-level assessment to factor out possible confounding variables; 6-21 years.). As discussed in section "Prediction, social timing, individual motor planning, and social motor synchrony in early autism," hypersensitivities, sensorimotor "noise," relative latency, and disrupted multimodal integration all have the potential to set people apart in time and disable just-ahead-in-time prediction. In section "Autism and Auditory-Temporal Processing" in particular, we outlined the case for predictive delay and/or asynchrony in autism in response to isolated sonic events. However, when presented within simple or complex rhythms, prediction error was completely absent - no difference was found in ERP response patterns between individuals with ASD and neurotypical controls.
Importantly here, our concept of rhythm is information-rich; full of temporal and non-temporal cues (potentially multimodal) to guide participants to on and off-beat moments in time, intention, and action. This is crucially different from the clinical tick-tock of the metronome. A meta-analysis of "tapping studies" (), included six studies which examine unilateral (simple) movement response patterns17 (i.e., basic tapping) as a synchronization response to "auditory stimuli". All but one of these, result in ASD subjects performing worse at synchronization than TD controls (as expected, see sections "Autism and Synchrony" and "Autism and Auditory-Temporal Processing"). One study,, was exceptional - demonstrating no significant difference between ASD and TD performance, and concluding non-verbal rhythm synchronization is intact for children with ASD. On examination, all of the preceding five studies presented auditory stimuli as a "paced beat" (a straight tick-tock generated by computer or metronome). presented audio recordings of woodblock rhythms (complex, medium, and simple meters). We suggest this stand-out feature, in relation to the stand-out result, is not coincidence.
 explored the impact of dyadic drum playing on children with HFA, concluding that the presence of rhythmic cueing and sensitive tempo adjustment correlated with improved measures of social skills. Recruiting this information-rich rhythmical interaction as an intervention over time, facilitated synchrony between children with ASD and neurotypical partners. After the intervention, participants showed decreased asynchrony when tapping with a partner at adjusted tempi, and showed greater engagement in joint attention and action.
 developed a synchrony training program in which children with ASD were shown a progression of meaningless arm movements, with associated melodic/rhythmic scaffolding, and were asked to imitate the movements. Over 6 weeks, the children improved across increasingly difficult task variants in measures of synchrony and imitation (ibid.). demonstrated that, over 8 weeks, children with ASD benefited from a rhythm-based movement intervention, displaying improvements in body coordination, imitation/praxis, and interactive synchrony.
In a study designed to compare music versus non-music interventions, ASD groups were assessed before and after on measures of social communication and resting-state functional connectivity of fronto-temporal brain networks. Over 8 - 12 weeks the music intervention group (where improvisational approaches, involving song and rhythmic scaffolding, were used to target social communication and sensorimotor integration) scored significantly higher on a measure of pragmatic communication (P = 0.01). Significantly (P < 0.00001), post-intervention resting-state brain connectivity was lower between auditory and visual regions in the music compared to the non-music groups, showing a reduction in disruptive over-connectivity (known to be prevalent in autism, ibid.; + see).
The human ASR is a neurophysiologically fast and direct response to certain sudden, unexpected auditory stimuli. ASR latency - the time from presentation of the startling stimulus until neural response - provides an index of neural processing speed. As discussed in section "Autism and Auditory-Temporal Processing," individuals with autism demonstrate prolonged unmodulated ASR latency as compared with age-matched TD controls (though without controls for LD, *). Understanding the conditions which modulate latency is important for us here as, if we can minimize relative TD-autism latency difference, we can improve alignment for synchrony. When startle stimuli were presented with pre-stimulation and/or with habituation18, latency differences and auditory hypersensitivities (shown via ASR amplitude) became non-significant (ibid.). Clearly, predictive information - through context and familiarity - matters.
Rhythmic Relating will build on the pulse inherent in the client's movement, sound, or object-play and augment it with clarifying qualities and tailored multimodal cues. This client-centered rhythm will provide a flow of predictive information and compelling pulse - clarifying the practitioner's communication and providing a framework to facilitate sensory contiguity, discernment, prediction and just-ahead-in-time planning.
Recently an innovative computational approach to the automatic categorization of music (X-System) has proved successful in predicting emotional, arousal, and mood responses to music. Certain specific psychoacoustic qualities produce extremely direct, evolutionarily pertinent responses in humans. These include ASR-stimuli and acoustic activation contours. have used the term brain stem turbulence to describe these sounds, with reference to the degree to which these sounds constantly change in ways which activate and move us.
The ASR operates along a pathway leading directly from the cochlea, along cranial (auditory) nerve VIII by way of the lateral lemniscus, to the caudate reticular nucleus. From here, there are descending projections to spinal and limb motor neurons, provoking the "jump" or "blink" effect.
Acoustic activation contours are evolutionarily significant sounds indicative of the positioning and movement of the human body in space and time (from sudden approach, to slowly moving away). This may extend from separation cries, or the hissing of snakes, to rapidly approaching sounds, glides, falling, fast crescendos, bursts of sound and the like. It is very likely that these sounds are recognized by innate systems early in auditory pathways (; re: the Inferior Colliculus,). There is clear evidence of these pathways ascending to emotional systems, as well as a descending, emotional "feedback" pathway from the amygdala.
Music plays with the use of turbulence, specifically taking the "dangerous" edge of activation and, through context, timing, and expectation, leveraging that energy for joy, wonderment, and anticipation. Moments of relative acoustic startle can provide defining beats and turning points. Acoustic activation contours can, individually, stimulate changes in mood and energy, and, used as repeating rhythmical structures, they can define the mood of extended moments or of a whole piece of music.
Turbulence compels response through movement. Turbulence is neurophysiologically direct vitality communicated instantaneously via sound. Sensitive use of turbulence may provide people with autism with a palette of sounds which represents their most-direct audio experience (relatively decreased latency and increased signal-to-noise ratio). This sensitive use will include tailored multimodal experiences, time given for familiarity and habituation, and modulated volume within an information-rich rhythm. Most clients with Autism(Therapeutic Needs) will find loudness intolerable (stimuli > 80 dB - which is akin to shouting, twice as loud as conversation), and some may be hypersensitive to particularly high-pitched sounds at normal-to-mid-range volumes. For many clients then, we could start quietly, experimenting with relative acoustic startle and low-volume acoustic activation contours. As such, we may be able to use turbulent rhythmic structures (accents and contours) to add guiding information and energized pulse into interaction with a client with Autism(Therapeutic Needs).
Turbulence may also help us share emotion, mood modulation, and co-regulation. Akin to its use in music, when turbulence is presented sensitively within interactive social rhythms (defined by structure, predictability and safety - i.e., the absence of threat) the mobilization (fight/flight) potential of turbulence is likely to become the stuff of joy, anticipation, and play.
Here, we introduce the concept of a tonescape: a "landscape" of interactive possibilities, spanning a wide range of modulated turbulence and synchrony; a landscape full with a variety of co-regulatory narrative arcs, leading partners in and out of varying levels of arousal and emotional tone. The tonescape can bring opportunities for small-step co-regulation and layered SI. The range of modulated turbulence in the tonescape, reaches from the poignance of peace shared, to the wonderment of subtle variation (playful, fluid, unexpected, an emotional "hide-n-seek"), to the raw joyous anticipation of "peek-a-boo."
Activation contours are short expressions of quality which stimulate an (inter)active state change. They are single events, often multimodal, communicating vectors of intention in movement and sound, containing "...the felt experience of force... with a temporal contour and a sense of aliveness, of going somewhere" (, p. 3). Activation contours can be the building blocks of a developing game - shared experiences in repetition or combination. They can be tools for the embodied reflection of vitality. They can be recruited as stand-alone events, promoting interest and motivation if things feel stuck. And they can also be integral to rhythmic synchrony scaffolding (see later) as up-beat guides to an on-beat shared moment.
Activation contours come in a huge variety and subtlety of types. Here we describe seven of them - possibly the most prevalent in interaction19, and those which we have found most useful to consider in practice:
Up-Swish - an upwards inflection guiding toward a moment in time, space, expressed energy, and emotional tone.
Down-Swoosh - a downwards inflection guiding toward a moment in time, space, expressed energy, and emotional tone.
Stretch - a consciously elongated up-swish or down-swoosh.
Burst - an instantaneous, exploding energy often in an outward, interactive vector.
Quick-fade - the opposite of the burst, an instantaneous imploding, withdrawing vector.
Waver - a wavering vector in either an up-swish, down-swoosh, or an even plane.
Pulse - a pulsing vector in in either an up-swish, down-swoosh, or an even plane.
Activation contours can be expressed in any sensory modality or combination of modalities. When envisioning combination possibilities, we have found the following constructs useful (some single-, some multi-modality):
Volume - volume change (including silence).
Proximity - positional change (relative to the other player).
Embodiment - whole-body, postural change.
Intensity - change in the level of energy invested.
Pitch - audio pitch change.
Timbre - vocal emotional-tone change.
The "Monster belly blow" game (section "What Does Disrupted Bidirectional Social-Motor-Synchrony Look Like in Play?") involved the father using a rising vocal inflection (Up-swish in volume, pitch, timbre) whilst looming in toward his daughter (Up-swish in: proximity), then a falling vocal inflection (Down-swoosh in volume, pitch, timbre) whilst looming away (Down-swoosh in proximity), and the "Belly blow" (Burst in volume, intensity, and timbre). Other examples are, an energetic star jump (Burst in embodiment and intensity), pulling a client along a smooth floor, cradled in a blanket, with a sideways waggle [Stretch (with interspersed Waver) in proximity, embodiment, intensity] bouncing with a client on a trampoline [Pulse (vestibular) in intensity, embodiment].
Here we introduce the concept of Rhythmic Synchrony Scaffolding: the use of rhythm (in any modality or combination) to match, accent, cue, augment, and develop the client's pulse in movement and sound.
Within music, beats can be easy to perceive, very difficult to perceive, or overtly non-existent. For us, a lock-on beat (useful in scaffolding rhythmic experience) is one that maximizes the properties which promote perceptual ease. These properties can be temporal or non-temporal.
The temporal properties of a rhythm can induce the spontaneous feeling of a beat. For a lock-on beat, it is helpful to keep a regular pattern with a simple meter, i.e., one with short duration intervals, and simple integer ratios. Simple meter patterns, as opposed to complex ones, have been shown to improve synchronization dynamics. In western music tradition, all time signatures (or meters) are constructed in patterns of 2 and 3 s. Our simplest meters are: 2/4 [evenly accented; defined by a march; example, the Imperial March (Darth Vader theme) in Star Wars]; 3/4 (accented, strong-weak-weak, strong-weak-weak; exemplified by a waltz); 4/4 (accented, One-and-Two-and, One-and-Two-and; examples: the straight "money-beat" which opens Michael Jackson's Billie Jean, or defines Mozart's, "A Little Night Music" and Pachelbel's Canon in D major).
In beat perception, the basal ganglia-cerebellum partnership displays different patterns of activation on attempted perception of simple or complex meters. Using a lock-on beat will engage the basal-ganglia/pre-motor-area relationship, as: "...functional connectivity between part of the basal ganglia (the putamen) and cortical motor areas (the pre-motor and SMA) is higher during perception of beat rhythms compared to non-beat rhythms" (, p. 35, italics added).
Lock-on beats will also simplify cerebellar processing demands and limit the demands of beat generation on the basal ganglia. In rhythm tracking studies involving patients with brain lesions, "... for cerebellar patients... negative effects were... specific to the rhythm played at a fast tempo, which places high demands on the temporally precise encoding of events. In contrast, basal ganglia patients showed more heterogeneous responses at beat frequency specifically for the most complex rhythm, which requires more internal generation of the beat" (, p. 156, italics added).
We can also simplify lock-on through choice of periodicity. Many potential rhythms have several levels of periodicity present. For example, in "twinkle, twinkle, little star," one can tap regularly to every syllable, every other syllable, or every fourth syllable, and still be synchronized to the music. Initially, we can choose to accent a well-spaced level of periodicity (for instance, the fourth syllable in the above example).
The temporal accents present in certain rhythmic patterns can act as just-ahead-in-time guides, allowing players to land on a moment of emphasis. The feel of this is "the act of raising or lifting," followed by "setting down" - like lifting a foot before making a step then placing it down with precision. The raising acts as an upbeat, anticipating and guiding the on-beat. In prosody, this is well exemplified by the iambic pentameter with an even pulse: da-Daah, da-Daah, da-Daah, da-Daah... In music, the "da-" becomes the upbeat guide to the "Daah."
In terms of non-temporal support, focal beats within a pattern can be accented with intensity accents. These are single beats, emphasized by a change of intensity in pitch, volume, and/or timbre. Intensity accents can make impacting use of relative acoustic startle.
Activation contours, with their turbulent, directional energy, can help guide a player to the beat, with just-ahead-in-time advance warning. Guiding a movement toward an intended goal (moment in time; point in space; specific purpose) involves such motor prediction. TD individuals use perceptual force-time curves (with a felt sense of expected time-to-closure) to organize the effective use of force in actions, and to couple these actions with the actions of another. In an arm-extension (for example, in expressive gesture, reach-to-grasp, or tap-to-a-beat), the motor image is a force-time curve of energetic enervation: rising on initiation, increasing to reach, falling in expectation to land on point-of-contact, or body-space goal with intention-specific appropriate force. We are proposing that activation contours can serve as guides for perceptual-motor force-time curves, helping us land on beat and act in synchronous time-scales (e.g.,).
 have shown that children with HFA have difficulties in perceiving vitality-form differences between two contiguous stimuli (smallest change detected at >100 ms apart). This suggests that, "during action observation, children with ASD need greater stimuli variations than TD children to detect their differences in terms of vitality forms" (ibid. p8). We can support clarity in contiguity through clear isolated communicative acts. Children with autism can often recognize extreme vitality, while lacking distinction of the more nuanced vitality-forms characteristic of everyday interaction. Playful interaction gives us the platform to use big, distinct gestures when needed - to initiate and to clarify - and then to build toward sharing more nuanced actions.
Any one vitality-form can be recognized via either visual or auditory expression. Indeed, have concluded, "...it may be plausible that visual information is not sufficient for children with ASD to encode vitality forms correctly and that the use of alternative (additional) perceptual information may help vitality form perception" (p. 8, italics added).
Dependent on the client's level of language comprehension, we can support vitality recognition through explicit labeling of the other contextual intention-dimensions: goal and emotion. We can verbalize what we are doing and our goal; we can verbalize what the client is doing (using their name in third-person) and their goal, if apparent. We can verbalize our emotions; we can verbalize the client's gross emotional state (happy, sad, angry, excited), if apparent.
A recent study by focuses on a bidirectional approach to motor dissimilarity in social contexts. Emphasized here, is the fact that TD adults demonstrate deficits in recognition of ASD vitality-forms even after information feedback. This bidirectional finding suggests that we should avoid our neurotypical-centric interpretations of vitality-forms and, until we have spent time tuning in to our client's expressions, we should begin with simple mirroring, observation, and trust-building.
Using structural magnetic resonance imaging, *) found that neuroanatomical systems that process speech and song are more effectively engaged by song than by speech, for children with ASD. We can use a melodic "story-teller's" voice (light and playful variation in pitch, timbre, volume, overall mood tone - a conscious avoidance of monotone) and/or we can literally sing our communication.
As is the case for short-interval parsing for ease of lock-on in beat perception, short spoken units support ease of rhythmic parsing in language comprehension. Whole utterances in a mother's baby-talk to very young infants tend to be short (about 0.5-0.75 s). They are typically repetitive and with rhythmic intonation and undulating pitch. The regular, simplified rhythms undoubtedly help the infant to synchronize (ibid.).
As we sensitively move on from acclimatization, beginning to add elements to our client's rhythmic and sensory experience, we should do so only in small increments. We should add, remove, or adapt, just one layer at a time - Layering the Senses. We need to be careful to observe which, and how much sensory input the client can tolerate and engage with. As functional integration occurs, we can extend sensorimotor experience in small-steps, layering in and out of the client's thresholds of sensory vocabulary and tolerance.
Piggy-backing on intact beat-perception pathways in autism, support for social timing should recruit tailored, information-rich rhythmic parameters to engage and clarify interactive pulse and relatable vitality. These lock-on parameters include beat specificity, periodicity, temporal and non-temporal accenting (including relative acoustic startle), and the use of activation contours (turbulent acoustic, and multimodal) as guides for perceptual-motor force-time curves. SMS support should facilitate good-enough synchrony as a basis for shared experience - enabling small-step co-regulation and a layered approach to sensorimotor integration. Initial and on-going environmental priorities should be acclimatization, simplicity, sameness, calm, short duration interaction, and rest. Interactive priorities should be: starting with the client's spontaneous movement, sound, or object-play20; isolating, accentuating, and simplifying initial focus behaviors; scaffolding with rhythm; leveraging movement (including touch) and sound in combination to maximize rhythmicity; leveraging acoustic turbulence to encourage movement-response and to simplify processing load; then extending co-regulatory experience and sensorimotor integration through small increments within a varied tonescape.
We acknowledge the pervasive nature of timing and sensorimotor disturbance in autism. We are open to the possibility of rhythm-mediated SMS entrainment in interaction, yet expect that (as was found by) such support will take the form of temporary scaffolding. The aim here then, is to facilitate small-step co-regulation and sensorimotor integration within a zone of proximal synchrony.
Rhythmic Relating offers a skill set21 that can be flexibly applied, as and when feels useful, when supporting playful interaction with a client with Autism(Therapeutic Needs). The skill set can be used independently, or in support of the play progression we present in Section "The rhythmic relating play progression: building games together (from movement, sound, or object-play)." The benchmark here is the essential quality of co-creating, and passing through experiences together - synchrony for its own sake. There are no interactive expectations, fixed rules for progression, tick lists or programs. Rhythmic Relating is about facilitating realistically short moments of playful synchrony whilst respecting overwhelm, and the need for rest and withdrawal.
Phrases of playful interaction might be led by the client, sometimes the practitioner, often (and ideally) both in co-creation. In practice, the question of who is leading, is of far less significance than the sense of togetherness in synchrony. If the phrase is practitioner-led, then what is important is that the client is actively experiencing in relative synchrony. Or, if the phrase is client-led, then the practitioner should be actively following, ready to respond and develop. As practitioner, we can keep in mind this rule of thumb: follow-lead-follow. We follow the client's momentum, yet we feel free to take an initiating lead when it feels appropriate, then follow again when the client picks up the flow in response or lets us know that we have missed the mark - always careful not to coerce the client.
Please refer to the overview of the Rhythmic Relating skill set (Figure 3).
In what follows, we outline a series of reflective engagement skills which range from Selective Mirroring (Initial) (with close affiliation to simple imitation), through to a fully embodied, multimodal reflection of the client's vitality in Mirroring (Vitality). The range represents our small-step priorities: initial simplicity, low arousal, sameness, isolation and accentuation of one particular aspect of the client's movement/sound/object-play; then playful development; with extension of co-regulation and sensorimotor integration through sensitively layering the senses.
In deciding which skill to use and when, it is important for the practitioner to act from a place of embodied observation, attempting to immerse themselves in how the client is experiencing and communicating. Isolated, simple mirroring may be perceived as a welcome simplicity, clarity, and validation to the client with Autism(Therapeutic Needs). Or it risks being perceived as judgmental and patronizing. We need to spend time attuning to find what is helpful, and always remain sensitive to adjusting, based on felt-sense feedback from the client's embodied communication.
We isolate a selected aspect of the client's movement or sound to mirror. We might select a behavior, gestalt, or motif for its clear, repeating nature, or because it is marked by a noticeable emotion, mood tone, or level of arousal. We want to hone in on this behavior, bring awareness to it, accentuate its affective and expressive tone (we might exaggerate or diminish our reflection for emphasis), and minimize other elements of our behavior to allow this to stand out. Here we can use big distinct movements and/or clear amplified sounds as appropriate, later, progressing toward more nuance.
When developing a game, we will need to be able to modify our interactive responses without losing connection with the client. While matching the overall quality of the client's behavior, we can play with modifying our mirrored movement or sound, one aspect at a time. Here are some aspects to consider. In movement22 : effort (pace, weight, fluidity); mood (emotional/energetic tone); structure (use of body as a whole vs. in parts; place of initiation of movement; placement/movement of limbs in relation to torso; upper-lower body relationship; left to right body relationship; contralateral body relationship; place of initiation of movement); space (proximity - near, mid, far reach; height level changes). In sound: volume (use of accents, crescendo vs. decrescendo); pitch (contours of sounds); timbre (breathy, soft, or vibrato voice or sound); form (musical motif or pattern); tempo (fast vs. slow and changes in between); articulation/length of sound (legato, staccato, tenuto). While maintaining the overall style, we can also play with either exaggerating or diminishing a mirrored aspect of the client's behavior.
We use our kinesthetic empathy, all our observation skills, to feel our best-approximation of the whole-body/whole-sound vitality-form being communicated by the client in any one moment, in series, or in a repeating rhythm. Vitality-forms (including stillness and inaction); psychoacoustic dynamics (including silence); and/or extended patterns of vital quality, can be "mirrored" in various ways - the energy, shape or contour of vitality being re-communicated in essence. When we mirror vitality, we often use activation contours. We can match the energy and intensity of the client's behavior without imitating or overinvesting in the particular emotional tone. This enables a safe, congruent way to connect, without fueling negative emotional patterns. Vitality can be mirrored as:
- An alternate expression within the same modality, for example: a client's slow, rhythmic hand clench-and-release matched by a whole-body contract-and-open; a client's anxious moan matched by mixed-pitch bubbling sounds (up-swish contour in pitch and volume, with a high level of turbulence, matching the energy contour but without replicating or fueling the anxiety); a client's violent jump matched by large body movements flowing from the core (matching the energy release without turning up the anger).
- A cross-modal expression23 (matching with a different modality), for example: the arc of a client's arm movement matched by a down-swoosh contour in pitch and volume; the pulse of a client's vocalization matched by a foot tap; a client's sad vocalization matched with a sensitive whole-body folding; a client throws a pillow energetically at the wall, the arm movement matched in build-up by a playful vocalization (up-swish in pitch and volume) and then accompanied in the throw by a matching "whoooosh" (burst in pitch and volume).
- A multimodal expression, for example: the client is energetically pushing a toy car back and forth, practitioner adds a swaying vocalization while swaying themself; the client is pouring sand from their hand into a sand-tray, practitioner adds a vocal activation contour (stretching down-swoosh in volume and timbre - full of granular turbulence) and strokes both hands down the client's arm.
A sensitive mirroring progression (through selective mirroring (initial), and on to same modality, cross-modality, then multimodality mirroring (vitality), with playful selective mirroring (modified) along the way) is an important dimension of layering the senses. In conjunction with the layered use of rhythmic support skills, we suggest this progression represents a useful small-step approach to facilitating sensorimotor integration in playful interaction with clients with Autism(Therapeutic Needs).
 described how, in rhythmic/tonal grounding, the practitioner keeps a steady beat (simple meters - 2/4, 4/4, or 3/4 recommended) as a stable "anchor" for the client's expressions. This can be done by humming, singing, simple beatbox, repeating words, with a percussive "instrument" (drum, box, body, floor, soft shaker), or by playing a bass tone. In the early phase of interaction, this may provide a hyper-aroused client (for instance, anxious in a new situation) with a sense of rhythmical containment. Preferably, we will soon be able to pick up and match the pulse inherent in the client's current movement or sound, and our rhythmic grounding will morph into the practice of rhythmic synchrony scaffolding. Or, if we cannot find this pulse, we continue on with the possibility that our rhythmic grounding will become integrated into the client's behavior, adding pulse and regularizing heterogenous elements. The more complex the client's behavior, the less likely we will find that initial pulse - or at least, a pulse we can readily connect with via a regular beat. In this case, especially with loops of object-play, we suggest rhythmic grounding can bring a useful sense of containment and momentum and be a rhythmic foundation for other Rhythmic Relating skills (e.g., link in the loop and jazz gaps, see later).
Rhythmic Synchrony Scaffolding (Initial) - is the use of rhythm (in any modality or combination) to match, accent, cue, augment, and develop the client's pulse in movement and sound.
In rhythmic synchrony scaffolding we prioritize picking up and accenting the client's spontaneous pulse in movement, sound, or behavior patterns. We bring our expression into closer rhythmical alignment with that pulse. We make our behavior more obvious, describing intention with rhythmic accents, cues, and contours; describing what is to come, just-ahead-in-time. We may also bring clarity and energy to add to the existing pulse. Ideally, yet with sensitivity to the client's sensory preferences24, we will start with a simple modality combination25 : auditory pulse (humming, singing, simple beatbox, using percussive "instruments" [drum, box, body, floor, soft shaker], or playing a melodic instrument with percussive emphasis) and visual/movement pulse (repetitive movement from the practitioner, defined in space and proximity). We need, always, to be aware of our impact on the client. We need to start simply (and stay simple for as long as needed), to match and be led by changes in the client's interactive arousal levels, and not to push a sense of urgency or overwhelm with our added pulse. This is very much: follow-scaffold-follow.
We can choose to accent a repeating aspect of the client's movement, sound, or object-play. We will use simple meters: 2/4, 4/4, or 3/4. We will choose a well-spaced periodicity for our accents. For instance, if a client is swaying left to right we could accent each sway (within a 3/4 meter); if a client is hand-flapping we could accent each fourth flap (within a 4/4 meter); if a client is repeating a spoken phrase we could accent the start, end, or a rhythmically significant mid-point of the phrase (within a 4/4 meter); if a client is walking around in a loop we could accent each second step (within a 2/4 meter); if a client is sliding on the floor, pushing a toy bear, we could accent each end-point of the slide (within a 4/4 meter).
In selective mirroring we hone in on, accentuate, and bring awareness to a particular aspect of the client's movement or sound. In rhythmic synchrony scaffolding we could choose to accent that same aspect.
We can improve our accenting with:
 - Temporal guiding information - the up-beat of, for instance, the iambic pentameter (remember, da-Dum, da-Dum, da-Dum, da-Dum - with the "da-" upbeat as guide). 
 - Non-temporal guiding information - we can explore the use of relative acoustic startle for focal accents; tailoring our ground-zero-volume to each client's needs (often below average conversational volume i.e., <60 dB), employing the playful "shock" factor of immediate variation in pitch, volume, timbre; using drum-like bass tones; the hiss-factor of a high-hat-like-tone; the surprise of a higher-pitched machine-like pulse (e.g. a laser gun sound effect); "magical" pulses like bell and triangle tings. Here we can also bring in sound effects (animal noises, cartoon character refrains (Homer Simpson's "Doh!" as a perfect beat), machine and vehicle sounds, impressions) and focus words as accents. 
We can use activation contours as guides to direct the client toward on-beat timing and toward our accents. Perfect for turbulent activation contours are any sounds with lots of inherent movement: glides; crescendos (including "whhhooop"-like sounds); variations on playful hissing ("ssss," "ssshhh," blowing sounds); sounds with high levels of randomized internal movement (bubbling noises, raspberries, tongue wobbles); contoured spoken words (with movement in pitch, volume, timbre); contoured sound effects (cars vrroooom, animals squark, woof, growl - and if you can manage an elephant trumpet...!); and cartoon characters are literally designed for this, Scooby-doo's "Jshiiiicks! for example.
Here are two examples. Firstly, using 4/4, with high-energy acoustic startle to accent the two and four: one and "POW" and three and "POW" and..., tiiiIIISSSSHHHH "POW," the contour uses a turbulent up-swish pattern rising in pitch, volume, and adding timbre, all guiding toward the "POW" accent. Secondly, using 3/4 with playful, fairy-tale acoustic startle to accent the strong beat with a magical "TIIING": TIIING te te, TIIING te te, TIIING... SSSHhhhh, TIIING, te, te, the contour uses turbulent down-swoosh, falling in pitch and volume, toward a whispery timbre, guiding intriguingly to the "TIIING" accent.
We can experiment with sticking with the same patterning for some time, leveraging support from familiarity and habituation.
Once we have established a scaffolding pattern in which our focal accent is a selected aspect of the client's behavior - for example, a vocalization - we could adjust the rhythm to bring our reflection of their vocalization into closer synchrony with our shared forward-moving pulse (and therefore, complementarity). This can function as rhythmic repair of rhythmic irregularity. This can also evolve into co-vocalizing, where we mirror elements of the client's vocalization, bring it into a rhythm, and make up "songs" (verbal or non-verbal) as a development. We have found the practice of co-vocalizing to be a useful step toward turn-taking.
Our use of a link in the loop (see below) relies on establishing a shared rhythmic pulse (creating expectation and momentum) and then playfully "teasing" the client's expectation. More generally, this type of teasing-around-timing is a crucial early developmental ingredient when building and developing games (e.g., peepbo" vs. "pee....p-bo!" vs. "pe-ee........p-bo!").
As the richness of client-practitioner interaction develops, we may want to add layers of multimodality to our scaffolding (layering the senses). In addition to auditory and visual/movement pulse, this could include physical pulse (varying type, pressure and position of contact and touch), or facilitating proprioceptive and/or vestibular pulses for the client (through assisted movement - possibly using supportive equipment such as blankets, trampolines etc.). In our use of relative startle accents and activation contours we can add additional layers of multimodality and vary the range and tone of turbulence. We can play with modulating the tempo and volume of our scaffolding.
To promote an orientation, or if things feel stuck, one option is to add an element to the loop. The aim is to do something with relevance to the client's movement, sound, or object-play, yet appropriately novel (the right level of different - noticeable, perhaps humorous, but similar enough not to jar). We repeat this simple action or sound with regularity, at the same point in a loop. If pitched and timed well, our action or sound can become part of the loop - an integrated link. We have become essential to the completion of the loop. Here are some examples:
- With movement, client is running a circuit of the room, touching various points on the wall in a loop, practitioner adds rhythmic grounding and positions themself with their hand directly over one of these touch-points.
- With sound, client is humming and swaying, practitioner adds rhythmic synchrony scaffolding and adds their own movement (an activation contour, quick-fade in embodiment, a whole-body withdrawing and shrinking small) every fourth bar of a 4/4 meter.
- With object-play, client is sliding across the floor on their bottom, pushing a toy bear with their feet, practitioner adds rhythmic synchrony scaffolding and then creates a human-bridge (arched on all fours) for the client to pass through in their current trajectory.
- With movement, client is rocking, practitioner adds rhythmic synchrony scaffolding and rocks in synchrony, then taps the client's right hand on every fourth rock.
- With object-play, client is pushing a toy train around a track, practitioner adds rhythmic grounding and, each time the train passes the station, starts to chase the train with a toy car.
The link can replace an accent or phrase within rhythmic grounding or within rhythmic synchrony scaffolding (with or without a preceding activation contour). Alternatively, without rhythmic support, we can use a stand-alone activation contour in the lead up to a link. Then, from there, we can facilitate an orientation from the client, by either withholding the link (a jazz gap - see below); or changing our action or sound (appropriate novelty).
A jazz gap refers to a pregnant pause deliberately interjected into the rhythmic flow of communication. A jazz gap holds a silence longer than the natural on-beat demands. It has the energy of needing to be filled. A beat is expected, movement is compelled. We can play with the held duration of a jazz gap over a range up to around 6 s. If we push the duration much past this range, we lose the rhythmical impetus of the "here and now." "The current consensus in music psychology and cognitive neuroscience is that the ability to associate beats, or perform them meaningfully as a pulse, stops at around 6 s or 0.16 Hz... It is at this point that the mind and body can no longer "lock on" - either actively through playing, or passively through listening - to the rhythm as a pulse" (, pp. 18-19). We have not found studies which could provide equivalence for individuals with autism. As such, we will proceed with the tentative working assumption that the 6 s window is appropriate for the high-end of a sense of associated rhythm. Practically, it will be essential for the practitioner to retain their sense of the continued rhythm, and so the 6-s high-estimate remains entirely relevant to the therapeutic tool.
We can use a jazz gap within rhythmic grounding or synchrony scaffolding. We simply replace an accent or short phrase. For example, in a straight 4/4 where the two and four are accented "TISH" sounds (employing relative acoustic startle): One and TISH and Three and TISH and One and [Jazz Gap...]. Or with the temporal accent of an iambic pentameter - da-Dum, da-Dum, da-Dum, da- [Jazz Gap...]. Or we can introduce a jazz gap within, or at the climax of an activation contour. For example, in a 3/4 swaying waltz: Dum, tuh, tuh, Click, tuh, tuh, Dum, tuh, tuh, Click, tuh, tuh, whooooaaahh...Click, tuh, tuh, Dum, tuh, tuh, Click, tuh, tuh, whooaaaah... [Jazz Gap]. We can also use a jazz gap to replace an established link in the loop (see above).
Rhythmic Relating is about free-flow playful interaction. The play progression we describe, is a template which can be used flexibly. The progression may be useful in extending spontaneity toward experiences which facilitate co-regulation and SI. It may also provide a helping hand when things feel stuck.
Please refer to the overview of the Rhythmic Relating Play Progression (in pictures) (Figure 4).
Please refer to the overview of the Rhythmic Relating Play Progression (in words) (Figure 5).
Applicable throughout - see Figure 3.
See section "Acclimatization, Simplicity and Sameness".
We ask ourselves, "what might it feel like to be experiencing this moment through the client's particular structuring of their movement, sound, stillness, and silence?" We aim to become sensitive to the pulse and quality of the client's behaviors. We try to tune into energy, effort, momentum, emotional color, potentially non-intuitive time-frames for response, and direction of focus. We are attempting to attune to possibilities of shared meaning that we might not initially recognize or understand.
We start with the client's spontaneous movement, sound, or object-play. We attempt to connect with a particular aspect of their behavior - selective mirroring (initial) (section "Embodied Mirroring Skills" and Figure 3). If we are able to pick up on a repetitive, somewhat looping quality within the client's movement, sound, or object-play - use rhythmic synchrony scaffolding (initial) (section "Rhythmic Support Skills" and Figure 3). If not, we can use rhythmic grounding to add pulse (section "Rhythmic Support Skills" and Figure 3). In our rhythmic support, we should be led by the client's pulse and momentum where possible. If we are adding our own interpretation of pulse, we should be responsive to the possibility of rhythmic overwhelm (getting the momentum and mood wrong).
If things feel stuck, we can wait and be with that uncertainty. There is often potential in space and patience. Or, as a possibility - use link in the loop (section "Orientating Skills" and Figure 5) and/or jazz gaps and activation contours (section "Orientating Skills" and Figure 5).
In the Rhythmic Relating play progression, we have deliberately not defined a particular moment of initiation or specified an initiator. Instead, we are interested in the practitioner using the skill set, remaining sensitively open, and facilitating potential for bidirectional SMS. We consider the overt beginnings of an interactive phrase to be either, the point in which client/practitioner behavior shifts into closer alignment, or a moment of prosocial change in client behavior. Part of our practice is a continual tuning-in to possibly non-intuitive orientations from the client (Figure 6).
We also recommend the highly powerful practice of reacting as if any orientation is an intentional initiation from the client. This practice is a safety-net, ensuring we don't miss opportunities, and also promotes positive feedback loops for learned interactive behavior.
The simplest games tend to develop in a series of short phrases of playful interaction, each phrase building just a little on the previous, with the series tending toward a turning point (or peak) in a co-regulatory narrative arc (Figures 1, 4).
Each phrase (Figure 7) starts with an orientation. Broadly, there are three possibilities at this point. The orientation itself could be a shift toward synchronous alignment, with the client's behavioral pulse somewhat locking into the attempts of rhythmic facilitation made by the practitioner. Then there are two possibilities that come from the use of activation contours and jazz gaps (within our rhythmic supports): the client may have been compelled to move, to do something new; or, if we have introduced a link in the loop, the client may pause as something specific is expected of us.
As we are led into a shared period of developing synchrony, the type of orientation helps us respond and somewhat defines the terrain (the rough shape of the phrase to come: even, contoured, or pendulous):
- An even phrase is marked by both partners traveling alongside each other, through an even pulse, in simultaneity (exactly in-sync): walking; jumping; rocking; blinking; sharing a regular sonic pulse; placing Lego bricks with regularity etc. After orientation and an extended moment of experiencing our even synchrony, we can pause and seek response (preferably), or respond ourselves through selective mirroring (modified) (section "Embodied Mirroring Skills" and Figure 3) and or rhythmic synchrony scaffolding (modified) (section "Rhythmic Support Skills" and Figure 3). Then, a further orientation, and the next iteration of the phrase.
- A contoured phrase is one defined by an activation contour. Again, this experience is defined by simultaneity and traveling through the contour together. Either partner may be responsible for generating the activation contour, the other might be engaged in a relatively receptive fashion. What is important is that there is engagement and a sense of shared experience. After an extended moment of experiencing our contour together, we can pause for response. Contoured phrases tend to develop through increments of intensity and anticipation, tend to be repetitious in nature, building toward an overall crescendo peak (see section "What Does Disrupted Bidirectional Social-Motor-Synchrony Look Like in Play?"). The response, therefore, tends to be a subtle variation of "AGAIN"! However, there is also impact in occasionally breaking the expected rhythmic build-up through selective mirroring (modified) and/or rhythmic synchrony scaffolding (modified).
- A pendulous phrase is one specifically defined by action, then response, in complementary synchrony within a shared time-frame - the simplest being the back and forth of turn-taking, the more complex being patterns of response delayed or staggered in time. We use a variation of imitation in movement or sound - selective mirroring (initial) - or a repetitious action in object-play (throwing a ball; sliding a soft toy; pressing a switch etc.) to develop a turn-taking dynamic. After an extended moment in this shared synchrony, we pause for response and the next phrase. We can develop the game with selective mirroring (modified) and/or rhythmic synchrony scaffolding (modified).
We can facilitate sensorimotor integration, depth of relatable vitality, and a range of emotional and arousal experiences, all through our sensitive practice of layering the senses - mirroring (vitality) (section "Embodied Mirroring Skills" and Figure 3) and rhythmic synchrony scaffolding (extended) (section "Rhythmic Support Skills" and Figure 3). Over time, we explore a huge variety of co-regulatory narrative arcs (Figures 1, 4) across both simultaneity and complementarity in synchrony. Client and practitioner travel together in and out of the client's thresholds of emotional vocabulary, arousal, and tolerance. These co-regulatory arcs are like hills and mountains in the tonescape we travel through together (section "Recruiting Acoustic Brain-Stem Turbulence: Evolutionary Sounds That Move Us" and Figure 4). We co-create this tonescape, through cumulative experiences of turbulence, ranging widely from:
- A sense of wonderment - light-footed variation in levels of turbulence in subtle playful combinations. Alternating between different types of activation contours. Moving across varying dimensions of quality. Finding a winding path to a turning point (peak) which could feel like a whispered moment of shared significance.
- A building sense of raw joyous anticipation - high levels of turbulence. Sticking with the same phrase with similar activation contours, building the level of arousal incrementally. Moving forwards with increasing anticipation and momentum to a high-energy peak in release and usually laughter.
- An increasing depth of shared peace - minimal yet playful turbulence. Just gently together. Moving toward a peak and extended conclusion in poignant silence.
Please see the Examples in Practice (Figures 8-11) and Supplementary Material (Examples of Rhythmic Relating in Practice).