The resource allocation mechanism.
One mechanism explains why the four signals matter and why discriminating them from adjacent domains is worth the effort.
The brain is a resource-allocation architecture. Processing resources directed toward one demand are not available for another simultaneously. When the vestibular system requires more active processing than it should to maintain postural stability, it draws from the same finite pool of cognitive resources that reading comprehension, working memory, sustained attention, and fine motor output depend on.
The student is not choosing between paying attention and managing her posture. Her nervous system is making that allocation without her awareness or consent. The academic consequence is real, measurable, and not attributable to motivation, effort, or instructional quality. This is the mechanism by which vestibular constraint becomes academic outcome.
Observation
What you see
Frequency-rated, domain-bounded, behavioral descriptions. This is your role. This is what PSOF certifies.
Reasoning
What it means
Collaborative sense-making by the MTSS team. Supported by your calibrated observations. Not yours to produce alone.
Action
What to do
Support selection, tier decisions, referrals. Belongs to the MTSS team and the clinician. Not within the scope of this certification.
What this certification asks of you
PSOF certifies you as a calibrated observer. Your job ends at the Observation column. What you bring to the MTSS team is something that has never been reliably available before: structured, frequency-rated, domain-bounded data about what is actually happening in the classroom. That data changes the conversation. The team does the rest.