Published by Unseen Progress, an independent publisher of caregiver research. Last reviewed 2026-05-10. Part of the sensory processing research overview.
Short answer. The threshold for an occupational therapy evaluation is not "my child has sensory differences." Most children have some sensory differences, and most do not need a formal evaluation. The threshold is functional interference — the point at which the sensory profile is meaningfully limiting the child's participation in daily life, where home-level strategies have stopped producing change, or where the parent needs a coherent map of the profile to make the next decision. When any of those three is true, the research-backed move is a referral to an OT trained in sensory integration assessment. When none is true, watchful support at home is reasonable.
The AOTA practice framework (AOTA, 2018) defines functional interference as a sensory profile that limits participation in age-expected activities — eating, sleeping, dressing, attending school, playing with peers, family outings, community settings. The marker is not the intensity of any single response but the pattern of restriction across the week.
Concrete examples that meet this threshold:
One of these can be a temporary phase; a pattern of three or more sustained over months is functional interference (Miller et al., 2007; Schaaf & Mailloux, 2015).
A family that has read the basic sensory literature, set up reasonable accommodations, built a rough daily input plan, and seen the child improve — that family is in a good place and probably does not yet need an evaluation. A family that has done the same and seen things stabilise but not improve, or seen one channel improve while another worsens, or feels like they are guessing — that family has reached the limit of what general guidance can produce. An evaluation maps the specific profile across all eight sensory channels and produces a plan tailored to that map, which is more leveraged than continuing to extrapolate from general advice (Schaaf et al., 2014, 2018).
When the sensory pattern overlaps with another condition — autism, ADHD, anxiety, ARFID, developmental coordination disorder — and the family is trying to understand which is which, an OT evaluation contributes a piece the medical specialists usually do not produce: a structured map of the sensory profile. The OT evaluation does not replace the developmental paediatrician or the psychologist, but it provides data they cannot generate on their own. Zimmer et al. (2012) document the high co-occurrence rate and recommend OT-led sensory assessment as part of the differential.
Not every sensory profile needs an evaluation. The family of a child with a clearly mixed profile — auditory-sensitive at concerts but fine at school, vestibular-seeking at the playground but otherwise typical, mild food selectivity but growing well — can usually navigate with general guidance, accommodation, and patience. The marker that this is the right level of support is that the child is participating in age-expected activities without chronic distress, and the family is not consistently in over their head.
Watchful support at home is also appropriate when:
The watchful position should have an upgrade trigger. "If three months of consistent accommodation does not move things, we get an evaluation." Naming the trigger prevents the watchful position from drifting into indefinite waiting.
A well-conducted sensory integration evaluation typically includes (Schaaf & Mailloux, 2015; AOTA, 2018):
The output is not "your child has sensory processing disorder" or "your child does not." DSM-5 does not include SPD as a separate diagnosis, and the OT field uses Miller's nosology — modulation difficulties, sensory discrimination difficulties, sensory-based motor difficulties — to describe what is present, not to label a category (Miller et al., 2007).
The clinical literature is consistent that the most useful evaluations are done by OTs with formal training in Ayres Sensory Integration — typically a multi-month post-graduate certification, sometimes badged as SIPT-certified or as one of the more recent EASI or USC/WPS programs. STAR Institute (2020) and the AOTA Sensory Integration Special Interest Section both maintain registries that families can use to find appropriately trained clinicians.
Indicators that the right level of training is present: the clinician mentions Ayres, uses a structured questionnaire and standardised assessments rather than informal observation only, has a sensory gym (not just a desk), and produces a written report that names channels and proposes a structured intervention. Indicators that the depth may be insufficient: vague "sensory issues" framing without channel structure, no standardised assessment, recommendations limited to a generic worksheet of "brushing and joint compressions."
The research-backed intervention model is Ayres Sensory Integration delivered in a sensory gym, ideally one or two sessions per week for several months, with a parallel home-led sensory diet (Schaaf et al., 2014, 2018; Bundy & Lane, 2020). Systematic reviews show medium-to-large effect sizes on individualised functional goals when the intervention is delivered with fidelity. Effects are smaller and inconsistent for non-individualised generic "sensory exercises," which is why the formal evaluation and tailored plan matter.
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Unseen Progress publishes long-form caregiver research and builds research-backed daily trackers for the families covered. See the full sensory processing research overview for the complete framework.