Learning to Learn Part 3: Sensory Systems

A child at a desk is not using one sense at a time. The brain takes in several streams at once, sorts what matters from what does not, and tells the body what to do about it. When that sorting is efficient, a child can listen, watch the board, sit upright and write without consciously managing any of it. When it is not, school becomes exhausting long before the work gets hard.

This is Part 3 of our Learning to Learn series. Part 2 covered primitive reflexes; here we look at the sensory layer above them, and at how vision, balance and body awareness work as a team.

Key takeaways

• Occupational therapists usually describe seven sensory systems rather than the familiar five; proprioception (body position) and the vestibular system (head motion and gravity) are the two most of us never learned about.
• Vision and the vestibular system share circuitry: inner-ear signals are combined with visual, body-position and motor information rather than processed alone (Cullen, 2012).
• Reduced visual and proprioceptive feedback changes children’s handwriting more than adults’ (Guilbert et al., 2019).
• Sensory differences are more common in autistic children, and the vision findings are usually subtle rather than about sharpness (Ben-Sasson et al., 2009; Little, 2018). Noticing a pattern is not a diagnosis, but it is a reason to have the visual system measured.

The seven sensory systems therapists describe

Occupational therapists usually group sensory input into seven systems rather than the familiar five, and some frameworks add interoception - the sense of what is going on inside the body - as an eighth. The exact count matters less than the reason for it: two systems most of us never learned about do a great deal of quiet work in a classroom.

Auditory. Telling similar sounds apart, holding them in memory, following a multi-step instruction in a noisy room. Hearing can be normal while this processing is not.

Olfactory and gustatory. Smell and taste work together, judging whether something is safe or pleasant and reading texture, temperature and pressure inside the mouth.

Tactile. Touch reads pressure, vibration, movement and temperature through the skin, and is the foundation for body awareness and motor planning.

Proprioception. Receptors in muscles and joints report where body parts are without looking at them. This is how you touch your nose with your eyes closed, or grade how hard to press a pencil.

Vestibular. The inner ear senses head position, direction change, motion and gravity, contributing to balance, muscle tone, posture and alertness.

Visual. Light reaching the eye is only the start; the brain adds depth, location, memory and context before any of it means something. You will often see the claim that 80 to 85 percent of learning is visual. We do not use that figure, because we cannot trace it to a peer-reviewed source. What we can say is that vision is involved in nearly every academic task, and that it is measurable.

These systems arrive on their own schedule

None of this is finished at birth. A baby’s eyes may cross or wander for the first two months and should focus and track together by three (AAO); depth perception develops around the fifth month and is well established, with eye-hand coordination, by age two (AOA). Fine depth judgement keeps sharpening for years, with average stereoacuity improving from about 100 arcseconds at age three to 40 by age seven (Birch et al., 2008).

Vision and balance work as one system

The vestibular system is not a separate balance channel that occasionally consults the eyes. Inner-ear signals are integrated with visual, proprioceptive and motor information from the earliest stages of central processing, supporting everything from the reflex that holds an image steady on the retina while the head turns to voluntary movement (Cullen, 2012).

That pairing matters clinically. Among 101 children and teenagers referred to a concussion program, vestibulo-ocular dysfunction was present in 28.6 percent of those with acute sports-related concussion and 62.5 percent of those with post-concussion syndrome (Ellis et al., 2015). The joint AAP, AAO, AAPOS and AACO clinical report notes that most children and adolescents with visual symptoms after concussion recover on their own within four weeks, and that those who do not should have the vestibulo-ocular reflex, near point of convergence and accommodation examined (Master et al., 2022). In one retrospective series, 38 people with lasting post-concussion symptoms who were also diagnosed with a small vertical eye misalignment reported less headache, dizziness and anxiety after prism was prescribed - but that report is uncontrolled, comes from a single practice, and should be read as preliminary rather than as proof (Rosner et al., 2016).

Body awareness, posture and the pencil

Proprioception lets a child hold posture without thinking about it and grade pencil pressure, and it works alongside vision rather than instead of it. When researchers altered writing-surface friction and blocked the writer’s view in second graders, fifth graders and adults, letter size, speed and legibility all shifted, and children were more affected than adults (Guilbert et al., 2019). Developing writers lean on both channels, and removing one leaves the other unable to fully cover.

Two students, one classroom

These two sketches are composites drawn from patterns we see every week, not individual patients.

Student A

This student’s sensory systems integrate efficiently. She listens, reads the board and sorts fast enough to write only what matters. Proprioceptive feedback keeps her upright and her pencil pressure appropriate, and background sound, movement and smell get filtered out, leaving attention free for learning.

Student B

This student cannot easily separate what matters from the rest. His visual system is not delivering reliably, so he leans on hearing and writes down everything the teacher says. Poor proprioceptive feedback shows up as heavy pencil pressure and a tired hand, and every stray sound pulls at him. By mid-morning, managing all of it has used the energy the lesson needed.

When sensory processing works differently

A meta-analysis of 14 studies found sensory symptoms substantially more frequent in autistic groups than in typically developing peers, with the largest difference in under-responsivity, then over-responsivity, then sensation seeking, and the biggest gaps at ages six to nine (Ben-Sasson et al., 2009).

On the visual side the picture is subtle. Autistic children usually have normal visual acuity, but atypical eye movements, subtle visuo-motor difficulty, an increased prevalence of strabismus and an increased likelihood of astigmatism are more common (Little, 2018). That argues for a careful, unhurried examination, not for assuming a problem. Our special needs and developmental delays pages describe how we adapt testing when a standard exam room is too much.

Sensory-based intervention itself belongs to occupational therapy. A systematic review of Ayres Sensory Integration found 19 studies, six meeting inclusion criteria and three quality-appraised, and concluded it can be considered an evidence-based practice for autistic children aged four to twelve (Schoen et al., 2019) - a real finding resting on a small evidence base.

What this layer does and does not tell us

Everything above describes how a child gathers information; none of it is a diagnosis. Our clinical view at Vision & Learning Center is that when the sensory foundation is shaky, reading, writing and sustained attention cost more effort than they should. That view sits alongside the evidence rather than on top of it. The part we can actually measure is vision: eye teaming, focusing, tracking, depth perception and visual processing. What we notice about posture or balance we hand to the therapist who owns that assessment.

Next, Part 4 covers the motor systems these senses feed, and our pillar guide What can my baby see? traces visual development from birth.

If your child works harder than their classmates for the same result, a comprehensive developmental vision evaluation is a reasonable next step. Schedule an evaluation at our Boynton Beach or Boca Raton office and we will tell you plainly what we find.