What is CVI?


’Jigsaw’ Learning Using 3Z Approach

  • Zoom In - to Learn in small sections
  • Zip up - the learnt sections together
  • Zoom Out - and understand the bigger more complex picture

An approach to learning for those affected by a reduced level of visual attention due to simultanagnosia.

Throughout the Simultanagnosia Spectrum sections, and across this website, we have considered multiple cases of people with simultanagnostic vision.

We know that simultanagnostic vision comes from a non-conscious part of the brain (the posterior parietal lobes), which makes it extremely difficult to describe, because the person is not aware of it.

Mary wrote in her simultanagnosia gallery:

I've just had a look at the photos. I think they are good and connect with what I have said.

But sitting here now in my lounge where I can see everything around me, the simulated images seem so extreme. I don't feel like I walk around only seeing one element at a time. I know that is certainly not the case in my house, I feel like I can see everything. But then I think about when I was at an airport and could only see one sign, or at a music concert and how I could only focus on one person's red top.

But I think it is going to be hard for people to understand when looking at the images. They are going to go away thinking that's what the world looks like to me all the time, but it doesn't. I think that is why it is so important to have the written description alongside it.

This is why simultanagnosia is so hard to understand and describe. It is not only hard to see and describe for both the affected person and those closest to them, it also appears to be very inconsistent.

Connor has CVI, his mother writes:

If you see Connor at home, you wouldn't even think he had a visual impairment, he just seems to know exactly where he is going even though technically he is blind. If you take Connor anywhere unfamiliar however he won't last a second without walking into something or someone, or tripping over something, it is clear in these unknown environments he is functionally blind as a bat.

We are learning from many people affected by CVI, that given a choice, between viewing something on devices of different sizes, the overwhelming preference is for the smallest device (a smartphone). Furthermore, several people have expressed a preference to view films or programmes on an even more reduced screen on a smart phone, in some cases this may be a viewing area as small a postage stamp.

The preference was observed by simple choice (choosing the phone over the tablet), and also noting difficulties concentrating on the large screen.

Katherine is a child with CVI including simultanagnostic vision. Katherine's mother wrote:

It's pretty evident that Katherine much prefers to watch videos etc on a phone. YouTube videos, she prefers not to have on full screen. My Kindle is ok, as is her iPad, however, I observed a lot more eye movements with these, causing more work for her I think. A laptop screen and anything bigger than that is a complete no no. Katherine never watches TV and we have left the cinema early the few times we have been. I originally put it down to lack of interest but I think it's probably down to how little she can actually pick up on such a huge screen. Putting a question to Katherine is difficult due her cognitive delays but each time she has asked to watch a video, I've asked her what would she prefer to watch it on and each time it's been our phones.

Hope that helps, it's certainly helped me and it will be something I will be mentioning to school as they have a tendency to super size everything!

Mary is an adult affected by simultanagnostic vision.

Mary tried looking at a short film with subtitles on different sized screens and noted the following:

When watching it on my iPhone in YouTube, but not on full screen, I found it much easier to read the subtitles at the same time as watching the video. Normally when watching something on the tv with subtitles, I've found that I can't keep up at all. My eyes tend to dart all around the screen trying to pick up different elements of the picture. So I can either read the words or watch the image, but not both and sometimes I can't read the words in time. But when watching it on the small screen on the phone, I didn't feel the pressure to frantically try and see everything. I was able to read the words and then I knew I didn't have to move my eyes very far to see the picture. The picture wasn't overly clear, but it was enough for me to see the main elements and know what it was about.

I then watched it on my iPad (which is a 12"), again not in full screen. This time, because I knew what was coming throughout the clip, I was able to just relax and watch it and not frantically scan. It helped that I knew what the words said, so I didn't have to read them, although I mostly still did. The picture was clearer than on the iPhone, so I could appreciate the images better. It was like the preview helped me to relax and watch it without being affected by the visual issues. When it was on the small screen, I was affected and reacted, but because it was only a small screen, it didn't impact as much - does that make sense.

I then watched it on my computer screen and straight away found it too big (I was sitting at my desk and probably too close, normally when watching tv, I am a distance away from the screen).

So I think watching it on the iPhone first allowed me to get a better overall picture of it and understand it better, so that when I watched it on the medium sized screen I could relax and take more of it in.

However, just a side note. For me, I think this related to the interaction of trying to read the words and watch the image. I don't have too much trouble watching tv unless it is too fast moving. But I do have lots of trouble watching shows with subtitles (in fact I cannot do it at all).

It also made me think about going to the movies. I know I cannot sit at the front, in fact I really need to be sitting as close as possible to the back row. And I have lots of trouble focusing if it is too fast, or of there are flashing lights etc.

It would be interesting to see what it is like to watch sport on a small screen like the iPhone, as I do find that hard as well.

Later, Mary added:

I need a bigger screen for activities such as writing, emails and reading off the internet. I have a laptop with a 17inch screen and I have it set on the biggest visual setting. When writing a word document, I also have it up to about 150% and often at double line spaced, anything smaller and I get eye fatigue and pain. So, yes a smaller screen for viewing movies / videos, but a larger screen for concentrated work such as writing and reading. I think this is important because when parents are looking at devices for their child for school work, you don't want them to the smallest one they can, as some of the low vision principles still apply. For instance, a 12 inch iPad is much better for me to do work on than a smaller one.

In a familiar environment, having significantly reduced visual attention, can be compensated by memory, which includes having an excellent mental map, this is how Connor who is registered blind looks as though he can see very well when in familiar places like home and school.

The following pictures have been edited to simulate what significantly reduced visual attention might be like - how much can you understand?

Maybe you are trying to figure it out by looking at the background.  This surrounding visual information is not available to the person with simultanagnosia, but it is easy to take for granted that it is, because it is how other people make sense of what they are seeing.  They zip all the visual information captured as their eyes glance around the scene to make a meaningful integrated whole.Maybe you are trying to figure it out by looking at the background. This surrounding visual information is not available to the person with simultanagnosia, but it is easy to take for granted that it is, because it is how other people make sense of what they are seeing. They zip all the visual information captured as their eyes glance around the scene to make a meaningful integrated whole.

Maybe this image seems a little easier.  None of these are meant to be tricks, they are just meant to illustrate what reduced visual information may be available to the person with simultanagnosia.Maybe this image seems a little easier. None of these are meant to be tricks, they are just meant to illustrate what reduced visual information may be available to the person with simultanagnosia.

Unedited pictures at the end of this section.Unedited pictures at the end of this section.

How do you think you did?

If you don't have reduced visual attention, you will have your experience, memories and recognition to help you figure it out, however for someone with reduced visual attention due to simultanagnostic vision this may be significantly more challenging, with a simple outcome - things don't make sense! And when things don't make sense, because you only have part of the visual information, yet it is assumed you have it all, a few things can happen:

  • You don't understand
  • You get frustrated
  • You feel stupid
  • You have accidents

You Don't Learn

Everyone has the capacity to learn, but reduced visual attention makes this considerably more difficult. The following approach is designed to combine the strengths of the person with reduced visual attention, whilst avoiding the challenges, particularly an overwhelming amount of visual attention.

We have used a range of examples to demonstrate this suggested approach. Each person with simultanagnostic vision is unique, so allowances may need to be made. The first example to explain the 3Z approach follows a boy called Daniel who has all the signs of Balint Syndrome. Daniel is obsessed with small straight purple things, and will hold a purple pencil or pen top for hours, staring at it. Daniel prefers to watch his programmes on a small Iphone screen. Daniel has normal visual acuity and normal contrast sensitivity.

Daniel likes small simple straight purple things, like a purple pencil.Daniel likes small simple straight purple things, like a purple pencil.

Consider this lounge below.

It is a nice clutter free area, possibly the sort of lounge someone like Mary who has simultanagnostic vision might like. We are going to bring Daniel into this lounge. First we will consider the challenges he faces, then work through the 3Z approach as a suggestion to help Daniel understand.

The first thing to note is the Daniel has a lower visual field impairment, which is present in many people with simultanagnostic vision.

So when Daniel enters the room for the first time he is likely to trip over anything in the bottom third of his visual field, including the coffee table, rug and edge of chairs. Daniel will learn to avoid the obstacles so long as they are not moved, but when mapping the room for the first time, it could be considered that Daniel's world is not anchored to the floor, maybe it floats?

In addition to a lower visual field impairment, Daniel also has simultanagnostic vision, which means he can only visually attend to a very small amount of visual information.

In the absence of any small straight purple things, it is possible Daniel's vision will be drawn to the next best thing - the spindles on the staircase.

Simultanagnostic vision is personal, as we explain in the Simultanagnosia Spectrum sections. In the absence of Daniel's preferred small purple things, his visual attention will be drawn to the nearest thing that has meaning for him, not the highest contrast (which in this room would be the red in the picture on the right). Daniel has a visual preference for items that are vertical.

So, to understand where he is, this is Daniel's visual information:

For this reason, Daniel:

  • Does not like going to new places. He doesn't understand where he is, and is frightened, both of accidents because he walks into things and because he is confused. He will become agitated and sometimes physically aggressive to avoid new places. Had his mother brought him to this nice, uncluttered house for a coffee with a friend, Daniel would be desperate to get out.
  • Does not like things to be moved around. Daniel has created important maps of the places he is most familiar with, particularly his home. Moving things creates the same anxieties as going to new places.
  • Resists new experiences, because making new maps is so difficult and stressful. These are part of the reasons Daniel was considered to have severe autism.

Daniel is first and foremost a little boy, with a world of adventures to explore outside of his familiar surroundings.

1.Zoom In

Let us consider that Daniel would benefit from getting to know this room, possibly a Music Therapist is based here, and if we can get Daniel past his anxieties of being in an unknown space, he might be able to enjoy and benefit from regular Music Therapy.

Zooming in is not just about limited visual attention. The room is an environment, and we need to break it down into bite sized sections that Daniel can cope with, including considering things Daniel finds challenging, including:

  • Unknown noises
  • Strangers
  • Sudden Movement

And , conversely, the things that will make things easier for Daniel, including:

  • A trusted person (his mother or father)
  • Soothing known songs
  • As little movement as possible, so as not to startle.

This will be hard for Daniel, and he needs to feel in control, so over time, let him step into the room, with his mother close by as a safety control - but not randomly. Daniel cannot easily zip together all the components of the room to make a whole.

This is how the room may appear to Daniel:

The individual pieces he is able to bring together with his simultanagnostic vision may not bear any resemblance to what a place actually looks like, here is a reminder of the room:

Daniel's mother needs to help Daniel put the pieces together in order, to join them together in a meaningful way, to make sense of his environment. Over time, this is a skill Daniel may well be able to develop himself to make sense of things, but in these early stages he needs someone to do it for him, to teach him.

Breaking up large of complex experiences into small single 'bite-sized' ones, and learning about the individual parts. We call this zooming in.

Start with the spindle Daniel was first drawn to, and take him there, to learn the distance across the room, to feel the top of the chair as he approaches, and to experience the steps to the left.

This is too much visual information for Daniel, but in addition to what he can visually attend to, his mother is building up a wider experience, and repeated over time, it will become familiar. It will become known. Then Daniel's mother can look at making the "meaningful known" bigger. There is no need to explore upstairs, so the next section will be the chair. With his reduced visual attention, Daniel would not even know which way around the chair should be to sit on it (he knows to feel for chairs before sitting down - a lesson learnt the hard way!).

The chair can be felt, and sat on, still keeping the environment safe for Daniel, still just with his mother, no strangers, no strange noises, safety is part of the "Zoom-in stage" that is repeatedly being reinforced, and it is very important to be considerate and not rush Daniel. As Daniel becomes more familiar with this section, we can more on.

2. Zip Up

As the two separate sections become known they can be zipped together, to make a larger understanding of what is known for Daniel.

Daniel can still only visually attend to this much visual information:

However, Daniel now understands this much:

3. Zoom Out

As the process is repeated and developed, Daniel learns more about his surroundings, and zooms out to understand an increasingly bigger picture, until the whole room makes sense to him, and he is able to start Music Therapy. Note, a stranger coming into the room is part of the process, and needs to be introduced just as carefully.

Over time, Daniel learns to understand the whole room, he has zoomed out.

Life is not as simple as a picture that can be broken down into equal parts, but the principles of 'Zoom in, Zip up, Zoom out' can be widely applied, however there are two possible challenges:

1 What if the person does not talk or understand language?

This may be an excellent opportunity to develop language. Use single words, do not clutter with sentences, and connect directly, repeatedly and consistently with the meaning. Don't be put off by big words like trombone or elephant! Sometimes a longer word might be easier to connect with.

The person may learn to understand the word even if they can't say it (this is called receptive language). It may not at first be obvious that they know and understand the word. If you are not sure, why not just assume they can and do - what's to lose?

2 The person has very poor visual acuity and can't see the smaller images.

This is the case for many people with CVI and was discussed in our section The Simultanagnosia / Visual Acuity Problem. Vision severely affected by CVI still can be useful:

  • Movement. Movement may be processed and recognised, particularly where the movement is unusual, characteristic, or meaningful.
  • Shape. A person may not be able to recognise things in relation to their detail, but may be able to recognise and remember their shape, like an elephant, particularly if this is reinforced with other 'elephant' things, like the movement characteristics of elephants, and the sounds of elephants.
  • Colour. Colour, particularly if reinforced with a shape, can form part of the understanding of the experience.
  • Add non-visual experiences, including the sound, and if available touch, but it has to be meaningful and related. The grey leathery feel of an elephant's skin may make no sense if experienced in a random place without the other 'known' experiences of 'elephant'.

The following example was given in the Simultanagnosia / Visual Acuity Problem section. Connor has very poor visual acuity (6/200, registered blind) and has virtually no language:

Understanding what a horse is, is the first attempt at teaching Connor how to attribute multiple experiences to one thing, and in turn develop a better informed more complex (right temporal) recognition knowledge. I started with one word, and one experience. The word was simply 'horse' but said very slowly and extending the consonants. I am teaching Connor to talk but it is very early days, however he has been extremely responsive. The word has to easily be connected with the action or experience. The word also has to be identifiable. Connor's processing is slow, so speaking at normal speed is too fast. Most people extend the vowels when speaking slowly, so horse would become hooooooooooorse, which to Connor would be ooooooooooo. Normally when I introduce a new word to Connor it connects with something he already understands, a clap or a bubble for example. With horse, I was taking the next step in introducing a new word with a new experience, which would be challenging. I extended the consonants - the easiest way I have found is just to say the word very slowly without the vowels - it sounds odd but Connor can really connect. hhhhhhhhrrrrrrrrrrrsssssssssss. For some reason I said it with a strong UK West Country accent! I think I just wanted to word to stand out.

I took Connor to his first horse-riding lesson and just used the word 'horse'. The experience and word were at first both new and meaningless, but we had to start somewhere, and after months of building up a relationship of trust, Connor was happy to be taken somewhere unknown and trust me. At the stables Connor panicked, not knowing where he was or what was happening, but once upon the horse it was like he was in a trance. Had he not enjoyed the experience we wouldn't have continued of course, but with this small seed we would start building Connor's knowledge of what 'horse' meant.

Connor quickly connected the word 'horse' with his weekly lesson, and within only a few weeks we were at the stage where the only day the word 'horse' could be mentioned was a Saturday - or Connor would think we were going riding. As Connor got used to the word 'horse' I was able to speak it without extending it, just speaking clearly, and not cluttering the word in meaningless sentences.

Connor's understanding of the word 'horse' is key. In addition to his weekly riding sessions horses feature in many other places, including:

1. On his computer game, a horse walks and Connor recognises the movement from the movement of the horses at his stables.
2. In his stories, one book has a button which when pressed makes a horse sound
3. A toy plastic horse that makes a horse sound

I linked these to the word 'horse', and in his own time, Connor has started to join the dots, and seeks out horse things. If there is a horse sound he is drawn to it, and he recognises the movement of horses.

Guided by Connor and his interests, we are using a similar approach to 'clothe' the words 'monkey' and 'train'.

Connor's mother 'Zoomed In' to breakdown understanding of what a horse is into small parts that would be meaningful to Connor, and through repeated experiences, slowing down, and adding to the experiences, Connor learnt more and more about horses. This is the 'Zoom in, Zip up, Zoom out' approach, and Connor is continuing to develop, as his mother explains further:

I really thought about and planned the approach to teaching Connor about horses, and am thrilled that I have finally found a way that he can learn. Some consider Connor to have a severe global developmental delay, or profound learning disabilities. I don't see him that way, I see him as having multiple filters meaning that things just don't make any sense, so he hasn't learnt to do very much at all. Using this approach Connor is showing me that he is capable of learning. What is interesting is that Connor seems to have picked up on it, and is adopting it himself where he can to learn more about things. This has shown me that Connor WANTS to learn, telling me in the only way he can, by trying.

I took for granted that we are born able to learn, it's such a basic thing, but that wasn't the case for Connor, because nothing made any sense. Connor had to be taught how to learn, and I am teaching him. This is neuroplasticity I believe, through these early steps, learning how to learn, Connor is no doubt creating new pathways in his brain, and in turn is developing new skills. I see no end to his potential.

Those helping people affected may be unsure how to know if something is perceived or understood. There is no simple answer, however the people who know the person best will be able to tell if they are engaged and happy. Very simply:

  • Observe
  • Document
  • Analyse
  • Understand
  • ...then repeat the cycle


Having reduced visual attention due to simultanagnosia can make understanding things very difficult. The person may seem to see things just like everyone else, they probably also think they see things like everyone else, but they don't. Over time, when there is no reasonable explanation of why they don't 'get' things, affected children don't understand even the most simple things presented at the typical pace and the typical degree of clutter, behaviours can develop.

This suggested approach breaks visual information that is too large or complex to process as a 'whole'; into parts, by zooming in to a manageable section. The size of this section will vary from person to person. Also, importantly, complex images require more visual attention than simple images, it isn't simply about size.

Our professional advisors commented:

Simultanagnostic vision is covered in great depth in scientific literature, but there is little or no information about how if can be best managed.

In this section, the description of what the subjective experience of simultanagnosia is like in different conditions, led to the idea of zooming in to a picture to gain the lie of the land, combined with memorising this information and then zooming out to the wider scene. This has proved very helpful .

This idea has been taken on board by parents of children who demonstrate features of simultanagnosia and optic ataxia who are unable to describe their vision, but whose learning and behaviours have all improved as a sequel to taking this information on board.

These are of course preliminary ideas, but the fact that these biographical stories are so compelling should make them first steps toward a new approach to teaching children with cerebral visual impairment causing dorsal stream dysfunction.

This material affirms that children can only learn from what they can perceive. The children described have made great strides since their perceptual limitations were recognised and acted upon by making it possible for them to learn.

A mind that is stretched by a new experience can never go back to its old dimensions.
Oliver Wendell Holmes, Jr. (Perhaps recognising brain neuroplasticity long before it was described?)

Further Examples:

The following sub-sections provide further examples:

Unedited Images


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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.