Crowding VR Film

Crowding VR Film

The Laboratory for Visual Neuroplasticity, Harvard Medical SchoolVideo Link:

This might seem like a simple test to measure a person's ability to spot a particular person in a crowd. However, how the person performs can tell us an enormous amount.

The Test

The challenge is to spot the school Principal (Headteacher).

The test has eye tracking software installed - the roving circle on the screen shows where the person is looking. This is particularly useful for people with reduced motor skills, who may take much longer to point at something, and for people with inaccurate guidance of reach (which can be caused by optic ataxia), meaning they miss what they were aiming at.

This programme has eye gaze software to recognise more accurately the time it takes the person to successfully accomplish the task.

There are different settings to make the task harder and easier, including

  • increasing / decreasing the number of people
  • adding background sounds (such as people chattering)
  • cluttering / decluttering the walls

What does This Tell Us?

Spotting someone in a crowd can be difficult due to many different reasons relating to CVI, for example due to poor visual acuity or difficulty with visual processing in crowded and cluttered environments. This specific test has been designed for people with sufficient visual acuity and contrast sensitivity to be able to see the images clearly.

To spot the Principal in the crowded hallway our brain needs to do a lot of things at the same time:

  • Process movement
  • Process a lot of visual information simultaneously
  • Recognise the person

For everyone with CVI, all aspects of their vision are unique to them and have a range, but repeated over time this test could not only measure the individual's level of visual perception, it can also tell us:

  • Areas across the visual field where the individual's visual attention is stronger and where it is weaker. There are different conditions affecting our visual field, and some affect attention, most commonly to one side (hemi-inattention or hemianopia or both). This test could detect these issues if present.
  • Show the optimum speed of movement. Many with CVI are affected by a condition where things are less visible if they move too fast (called dyskinetopsia). This test could match optimum performance with optimum speed, however the crowding and clutter will also affect performance and need to be considered.
  • Demonstrate the level of crowding and clutter affecting what the person can see and how quickly they can process it. This may indicate simultanagnostic vision, which is a condition where the person is very limited in how much visual information they are able to process during a limited time.

The same laboratory produced the 3D images of the brain we feature in this section, that show the significantly reduced processing channels the person with CVI has. With CVI, this seemingly simple task may be putting a lot of demands on too few channels or pathways, but will show the level the person is able to process.

With this information, to learn, everything in the real world (see below) needs to be no more demanding in terms of how many channels of processing are needed at the same time.

This information, if understood and acted upon, can be life changing for the person with CVI.

From virtual reality into the real world

  • If this particular challenge was difficult using virtual reality, it may suggest the person is affected by reduced visual attention due to simultanagnostic vision. Many affected by simultanagnostic vision are also affected by optic ataxia. Optic ataxia affects depth perception needed to guide movement and so, guidance of reach (this is why the eye tracking software is particularly important). Crowded situations, with many people moving around can be very stressful for people affected by optic ataxia, please read our section on Looming for more details.
  • This test does not look to measure challenges with facial recognition, however we know that this is also difficult for many with CVI.
  • In her Blog 8, Nicola McDowell describes the challenges of simply moving from one class to another, without the added difficulty of having to spot someone. While in her Blog 7 Nicola describes her difficulty seeing people's faces in a crowd. Both these blogs provide the real-life challenges associated with such simple tasks.

These tests are just that, tests, and for the above reasons the person is not expected to replicate their performance to the same level in the real world, where the added anxieties associated with CVI are present.

The Future

This type of testing, in addition to the invaluable information it provides about the individual, also could over time, in theory, become a training tool. The purpose of the work of this laboratory in relation to CVI is to consider the CVI brain, to identify where there are challenges, and then look at where different pathways could develop into alternative routes through neuroplastic change in response to targeted motivational training and hard work.

A training programme in the comfort and safety of home is never going to be a complete replica of the real world, however using simple exercises the brain can in theory be trained to scan complex scenes with ever greater speed and efficiency, which will definitely aid the person when out and about, and hopefully in turn enable them to participate more widely in social activities and live a fuller and more independent life. That is why these seemingly simple tests are so profoundly important.

Early results have been posted on the Laboratory's Facebook Page.

The Laboratory for Visual Neuroplasticity is seeking participants for their research (USA, Northeast region), click here for more information.

For further information please visit the Laboratory's website:

The Laboratory for Visual Neuroplasticity, Harvard Medical SchoolThe Laboratory for Visual Neuroplasticity, Harvard Medical School


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At CVI Scotland we are devoted to helping people understand cerebral visual impairments, and together working towards developing the understanding of this complex condition.