Modified Clinical Test of Sensory Interaction on Balance (mCTSIB)
Updated: 9/10/26
Essential Points:
The mCTSIB helps show which sensory systems you rely on for balance. By removing vision or making information from the ground less reliable, we can see how well the other balance systems compensate.
Difficulty in a specific condition can provide useful clues. Increased sway or loss of balance may suggest visual dependence, difficulty using somatosensory information, vestibular involvement, or a combination of factors.
Look for patterns, not diagnoses. The mCTSIB can point you toward a system that deserves more attention, but it cannot prove by itself that a particular sensory system is impaired.
Curious about trying the CTSIB-M for yourself or your clients? Explore my interactive web app, which guides you through the test, collects scores, and provides results in just 5-10 minutes.
For best accuracy, especially when working solo, I suggest using your phone to easily press the buttons while working through the test positions.
Balance isn't controlled by one system.
Your brain constantly combines information from three major sources:
Vision tells you what is happening around you and helps orient you to the environment.
The somatosensory system uses information from your feet, skin, muscles, and joints to tell you where your body is and what is underneath you.
The vestibular system in your inner ear detects head movement and helps determine your orientation relative to gravity.
Most of the time, all three systems are working together.
But what happens if we make one of them less useful?
That's where the Modified Clinical Test of Sensory Interaction on Balance, usually shortened to mCTSIB or CTSIB-M, becomes useful.
The test intentionally changes the sensory information available to you and observes how your balance responds.
It doesn't perfectly isolate one sensory system at a time. Human balance is more complicated than that.
But it does allow us to turn the demand on different systems up or down, giving us useful clues about which information you rely on and where your balance may be struggling. (1, 2)
Your Brain Can Shift Between Balance Systems
Imagine standing on a solid floor with your eyes open.
You can see the room around you. Your feet can clearly feel the ground. Your vestibular system knows how your head is moving.
Your brain combines all of that information to keep you upright.
Now close your eyes.
Visual information disappears, so your brain has to rely more heavily on somatosensory and vestibular information.
Next, imagine standing on foam.
You can still feel the surface beneath your feet, but that surface moves and deforms. The information coming from the ground becomes less reliable, so your brain shifts more attention toward vision and vestibular information.
This process is called sensory reweighting. (3,4)
Your brain is constantly changing how much it relies on each source depending on what information is available and how trustworthy that information seems.
The mCTSIB takes advantage of this process.
How the mCTSIB Works
The mCTSIB uses four standing conditions:
Eyes open on a firm surface
Eyes closed on a firm surface
Eyes open on a compliant foam surface
Eyes closed on a compliant foam surface
Each condition changes the amount or reliability of sensory information available for balance.
During the traditional clinical version, you attempt to maintain each position for up to 30 seconds. (1,2)
Keep your arms at your sides and use the same foot position throughout the test.
Stop the timer if you:
lose your balance
take a recovery step
move your arms to regain balance
grab support or require assistance
open your eyes during an eyes-closed condition
If you don't reach 30 seconds, you can perform up to two additional attempts and average the trials for that condition.
The maximum timed score across all four conditions is 120 seconds.
But don't make the mistake of thinking that 120 out of 120 automatically means your balance is perfect.
How you achieve those 120 seconds matters too.
Someone standing nearly motionless for 30 seconds and someone swaying dramatically but remaining upright have both completed the condition, but they're not demonstrating the same level of postural control.
What Kind of Foam Should You Use?
For clinical research, the type of foam matters.
Different thicknesses, densities, and stiffness levels can change how difficult the test becomes. Research has shown that changing the foam can change mCTSIB performance. (5, 6)
But if you're using this test at home to learn about your balance or track yourself over time, don't get so caught up in scientific standardization that the test becomes unusable.
Consistency matters most.
Use the same foam, the same foot position, and the same setup each time you retest yourself.
If you want something reasonably close to foam used in clinical and research settings, an Airex Balance Pad or similar medium-density balance pad is an excellent option. Airex balance pads have been used in published mCTSIB research and are a practical choice if you want a setup reasonably close to clinical testing. (6)
A random pillow or couch cushion can still create an unstable surface, but it won't necessarily behave like standardized testing foam. I also wouldn't recommend standing on a mattress or very soft cushion because the added instability can make the test unnecessarily unsafe.
If your goal is simply to explore how your balance changes on a softer surface, use what you have safely.
If your goal is to compare yourself with published research or normative values, the exact testing setup becomes much more important.
What Each Condition Actually Tells Us
This is where the mCTSIB becomes much more useful than simply adding four numbers together.
Each condition changes the sensory information available to you.
By looking at where your balance begins to break down, we can start developing hypotheses about which systems you rely on most and which areas may deserve more attention.
Condition 1 - Eyes Open on a Firm Surface
This is your baseline.
Your eyes are open and you're standing on a stable surface, so all three major balance systems are available.
Because all three systems can contribute and compensate for one another, this condition isn't very specific.
If you demonstrate excessive sway or have difficulty maintaining balance here, the problem is likely more than simple dependence on one sensory system.
Somatosensory information may not be contributing effectively. Vision and vestibular information may also be having trouble compensating. Strength, coordination, pain, joint mobility, medications, neurologic conditions, fear, and many other factors can contribute as well.
In other words, balance problems in Condition 1 are often multifactorial.
The next three conditions help narrow things down.
If This Was Hard, Try This
Start with the easiest version of standing balance.
Stand near a sturdy counter or railing with your eyes open on firm ground. Practice becoming comfortable standing with your feet progressively closer together before adding foam or reducing visual information.
If ordinary standing already feels unsafe or you're frequently losing your balance during daily activities, I would recommend a balance assessment before trying the harder conditions on your own.
Condition 2 - Eyes Closed on a Firm Surface
Now we remove vision.
With visual information unavailable, sensory reweighting shifts more responsibility toward the somatosensory and vestibular systems. (3, 4)
If your sway increases significantly when your eyes close, there are a couple of useful possibilities to consider.
You may have been relying heavily on vision during Condition 1.
Or your somatosensory or vestibular systems may not be providing enough useful information to fully compensate once vision disappears.
For example, someone with decreased sensation in their feet may appear relatively stable with their eyes open because vision helps compensate. Close their eyes, and that compensation disappears.
On the other hand, if sensation and other testing appear normal, a large difference between eyes open and eyes closed may point more toward visual dependence.
That's useful information.
It doesn't prove that another sensory system is impaired, but it tells us that your balance changes substantially when vision is taken away.
If This Was Hard, Try This
Start training with less visual help, not necessarily no vision at all.
Stand near a sturdy support and practice looking straight ahead instead of constantly looking at your feet.
As that becomes easier, you could briefly close your eyes while keeping a hand close to the counter or practice in a slightly dimmer environment.
The goal is to teach your balance system that it doesn't always need to depend so heavily on vision.
If you're extremely unstable when you can't see, or you regularly struggle walking in the dark, that pattern is worth mentioning during a balance or vestibular evaluation.
Condition 3 - Eyes Open on a Compliant Surface
Now we bring vision back but change the ground underneath you.
Standing on foam makes information from your feet and the support surface less reliable.
You can still feel the foam, so your somatosensory system has not been turned off. But the information isn't as trustworthy as it was on solid ground.
Your brain must naturally shift more emphasis toward vision and the vestibular system. (3, 4)
If Conditions 1 and 2 were relatively easy but your balance suddenly becomes much worse on foam, that tells us something important.
You may rely heavily on somatosensory information from the ground for balance.
It may also suggest that your visual or vestibular systems are not compensating as effectively when information from the feet becomes less reliable.
This is one reason someone can look perfectly steady on a flat floor but suddenly struggle on grass, sand, thick carpet, or another uneven surface.
If This Was Hard, Try This
Practice adapting to gradually less stable surfaces while keeping your eyes open.
You might start on a firm exercise mat, short grass, or another surface that is only slightly less stable than the floor.
Keep a sturdy support nearby.
As your control improves, you can gradually progress toward softer or less predictable surfaces.
The goal isn't simply to become good at standing on foam. It's to become better at adapting when the information underneath your feet changes.
Condition 4 - Eyes Closed on a Compliant Surface
This is usually the hardest condition.
Your eyes are closed, so vision is unavailable. You're also standing on foam, which makes information from the support surface less reliable.
That means your balance must place much greater emphasis on vestibular information. (3, 4)
This makes Condition 4 particularly useful when we're interested in vestibular contribution to balance.
If you have excessive sway or lose your balance here, vestibular involvement becomes an important possibility to consider, particularly if the first few conditions were much easier. Eyes-closed foam testing is commonly used as part of vestibular screening for this reason. (7)
It still isn't a pure vestibular test.
Your somatosensory system continues to provide information, and your brain still has to interpret all of that information and create an appropriate movement response.
But of the four mCTSIB conditions, this condition places the greatest demand on vestibular contribution.
One other pattern is worth watching.
If your performance in Condition 4 is almost identical to Condition 3, vision may not have been contributing much even when your eyes were open. That can be another reason to take a closer look at visual contribution to balance.
If This Was Hard, Try This
Don't immediately start practicing eyes closed on foam by yourself.
Break the challenge into pieces.
First become more comfortable with:
eyes closed on firm ground
eyes open on a softer surface
Once those individual challenges become manageable, they can eventually be combined if you have an appropriate safe setup.
If Condition 4 is dramatically worse than the others and you also experience dizziness, difficulty walking in the dark, imbalance with head movements, or unexplained unsteadiness, a vestibular or balance evaluation may be worthwhile.
Look for Patterns, Not Diagnoses
This is the most important rule when interpreting the mCTSIB.
The test can give us useful clues. It can suggest that someone relies heavily on vision. It can suggest that someone struggles when information from their feet becomes less reliable. It can point us toward possible vestibular involvement.
Those are valuable findings.
But they are hypotheses, not diagnoses.
Failing Condition 2 doesn't prove that your somatosensory system is impaired.
Failing Condition 3 doesn't prove that you have a visual or vestibular problem.
Failing Condition 4 doesn't automatically mean you have a vestibular disorder.
Human balance is too interconnected for a four-condition standing test to diagnose one isolated system.
Think of the mCTSIB like a detective. It helps narrow down the suspects, then other testing helps determine what is actually happening.
What About Sway?
The traditional clinical mCTSIB is primarily a timed test.
But I don't think that means we should ignore what someone's body is doing during those 30 seconds.
Someone who stands quietly for 30 seconds and someone who spends 30 seconds swaying dramatically from side to side technically receive the same timed score.
Those performances clearly aren't identical.
So pay attention to:
how much you're swaying
whether the sway increases when a condition changes
whether you're using your arms to control yourself
whether you're constantly fighting to keep your feet planted
whether one particular condition looks dramatically different from the others
Instrumented testing can quantify sway far more accurately than the human eye.
For home testing, you don't need to turn yourself into a laboratory. Just recognize that time is only one part of the picture.
The mCTSIB Doesn't Measure All of Balance
The mCTSIB is a static balance test.
That means it only tells us what happens while you're trying to stand still under different sensory conditions.
Real life asks much more of you.
The mCTSIB doesn't tell us how well you can:
recover from a trip
catch yourself after being bumped
turn your head while walking
step around an obstacle
climb stairs
change direction quickly
react to an unexpected loss of balance
That's why I wouldn't use an mCTSIB score alone to determine someone's overall balance ability or fall risk. It's one piece of the puzzle.
If you find a weakness here, that information can help guide what you investigate or train next.
What Do You Do With the Results?
Don't get overly focused on whether your total score was 94, 108, or 120 seconds.
Instead ask:
Where did my balance change?
Were you steady until you closed your eyes?
Did foam make a much larger difference than expected?
Was everything manageable until you combined eyes closed with foam?
Those patterns are usually more interesting than the final number.
They can help you identify the type of balance challenge that exposes your weakness and give you a logical starting point for training.
If a condition is difficult, start with an easier version of that same problem:
If closing your eyes is difficult, gradually reduce your visual dependence.
If foam is difficult, gradually practice on different surfaces.
If combining the two is difficult, train them separately before putting them together.
The goal isn't to stop using one sensory system. You need vision, somatosensation, and vestibular information.
The goal is to become better at shifting between them when the environment changes.
Final Thoughts: A Simple Test For Discovery
The mCTSIB is simple and that's what makes it useful.
With a firm surface, a foam pad, and a stopwatch, you can change the sensory demands of standing balance and see how your body responds.
You don't need to interpret every wobble as a medical diagnosis.
But you also don't need to dismiss those patterns as meaningless just because multiple systems contribute to balance.
If your performance changes dramatically when we remove or reduce a particular source of information, that tells us something useful.
Use it as a clue. Use it to guide what you explore next.
And most importantly, use it to better understand how your own balance works.
What’s My Fall Risk Score?
Most people don’t notice their balance declining until something goes wrong.
This 10-minute self-assessment will show you:
• How stable your balance really is
• Where you're most at risk (strength, coordination, or falling ability)
• What to focus on first
No equipment. No guesswork. Just clear answers.
References
Shumway-Cook A, Horak FB. Assessing the influence of sensory interaction on balance. Phys Ther. 1986;66(10):1548-1550. doi:10.1093/ptj/66.10.1548
Cohen H, Blatchly CA, Gombash LL. A study of the clinical test of sensory interaction and balance. Phys Ther. 1993;73(6):346-351. doi:10.1093/ptj/73.6.346
Peterka RJ. Sensorimotor integration in human postural control. J Neurophysiol. 2002;88(3):1097-1118. doi:10.1152/jn.2002.88.3.1097
Assländer L, Peterka RJ. Sensory reweighting dynamics in human postural control. J Neurophysiol. 2014;111(9):1852-1864. doi:10.1152/jn.00669.2013
Cohen HS, Sangi-Haghpeykar H. Differences in responses on the modified Clinical Test of Sensory Interaction and Balance on medium firm and medium density foam in healthy controls and patients with vestibular disorders. Biomed Hub. 2020;5(1):1-8. doi:10.1159/000507180
Boonsinsukh R, Khumnonchai B, Saengsirisuwan V, Chaikeeree N. The effect of the type of foam pad used in the modified Clinical Test of Sensory Interaction and Balance (mCTSIB) on the accuracy in identifying older adults with fall history. Hong Kong Physiother J. 2020;40(2):133-143. doi:10.1142/S1013702520500134
Cohen HS, Mulavara AP, Stitz J, et al. Screening for vestibular disorders using the modified Clinical Test of Sensory Interaction and Balance and tandem walking with eyes closed. Otol Neurotol. 2019;40(5):658-665. doi:10.1097/MAO.0000000000002173
