Test Protocols

Normal Findings

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0:00The healthy adult SOT shows a stereotyped pattern: scores in the high nineties on condition one, decreasing gradually as conditions become more challenging.

0:14Conditions one and two — eyes open and eyes closed on a fixed surface — should both score near ceiling. Somatosensation alone is enough to keep the body upright.

0:30Conditions three and four challenge a single input each. Most healthy adults score in the high eighties on both.

0:43Conditions five and six are the hardest — vestibular reliance only. Normal scores typically fall between 60 and 75, with some healthy individuals falling occasionally on condition five.

1:00The composite score — a weighted average across all eighteen trials — sits above 70 in healthy adults. Below 70 raises the question of impairment.

1:15The sensory ratios — somatosensory, visual, vestibular, and visual preference — should all be in the normal range, typically above 0.75 except for VEST, which is naturally lower.

1:32Visual preference, the ratio of conditions three and six to conditions two and five, should sit below 0.92. Higher values suggest hyper-reliance on visual cues.

1:49On the Motor Control Test, latencies fall between 120 and 150 milliseconds with symmetric amplitudes scaling appropriately to perturbation size.

2:06On the Adaptation Test, sway energy on the first trial drops by 40 to 60 percent by the fifth trial, in both toes-up and toes-down series.

2:24Knowing this baseline cold is essential. Every abnormal pattern is defined by its deviation from this template.

In this module

  1. What 'normal' looks likeFoundation · Trainee · Clinician
  2. Age effects on CDP measuresFoundation · Trainee · Clinician
  3. Test-retest reliability and learning effectsTrainee · Clinician

What 'normal' looks like

The healthy adult SOT shows a stereotyped pattern: scores in the high nineties on conditions 1 and 2, sliding gradually into the high seventies for condition 4, and bottoming out in the low-to-mid sixties for conditions 5 and 6.

The composite score sits between 70 and 85 in healthy adults under 60. Sensory ratios sit at: SOM ≥ 0.90, VIS ≥ 0.75, VEST ≥ 0.60, PREF ≤ 0.92. None of these cut-offs is exact — they depend on the normative database used.

MCT latencies fall in the 120–150 ms range with symmetric responses scaling appropriately to perturbation amplitude. The ADT shows clear adaptation, with trial five sway energy 40–60% lower than trial one in both toes-up and toes-down series.

Age effects on CDP measures

Age affects every CDP measure, but unevenly. The composite score drops by roughly 0.4 points per year after age 60, with most of the decline concentrated on conditions 5 and 6.

MCT latencies prolong modestly with age — about 1–2 ms per decade after 50 — and amplitude scaling becomes slightly less linear. The principal age-related MCT change is increased trial-to-trial variability rather than a shift in mean latency.

ADT adaptation appears to be relatively preserved with healthy ageing. Older adults adapt more slowly across the five trials but still show clear adaptation by trial five. Failure of adaptation in an older patient is not a normal age effect and should be investigated.

Test-retest reliability and learning effects

Test-retest reliability of the composite score is good — intraclass correlations of 0.7–0.8 over a few weeks in healthy adults — but individual condition scores are less reliable, particularly C5 and C6. Composite is the most stable metric for tracking patients over time.

Learning effects are real but small. Repeat testing within hours can improve scores by a few points, particularly on conditions 5 and 6. By 24 hours, the learning effect has largely washed out. Schedule serial CDPs at least a week apart to minimise this confound.

Diurnal variation is unhelpful but real — late-day tests typically show slightly lower scores than morning tests, attributed to fatigue. The effect is small (a point or two on the composite) and rarely clinically significant.