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Adapting Video for VI Learners

Effects of visual impairment

Problems with moving images

There are a very few people for whom it is impossible to see moving objects, people or images: they have a condition called akinetopsia. However, if you have other forms of visual impairment you may still have difficulty in seeing, or more likely, following or tracking moving images.

If you have restricted visual field and the action either starts in your 'blindspot' or moves into it before you can compensate you may have problems keeping up visually with the movement . You may even miss it altogether and be surprised by a new object or person suddenly being there. Compare the simulated clips below. Keeping the bird in view is not difficult for a person with unrestricted vision, even though it occasionally slips out of the highly acute central area of vision. However, such a change in direction makes it difficult for a person with a severely restricted field of view either to first locate the duck, and then to track it.

On the other hand, if the disability is due to control of the eye muscles, you may be able to see the object, but not keep it in the central part of your visual field, where details and colour are most precise. In the clips below, the swan is moving steadily and poses no problems for the person with good sight. However, random muscle spasms can make even this a problem: it isn't that the swan is completely lost from view, but that it can't be held in the centre of vision where most detail may be had.

>What are the effects of having problems with moving images?

If the problem is that the movement is too fast for you to track you may lose the object, person or action on the screen. If action takes place in several locations (either on-screen or between the screen and some other part of the learning environment, such as a concurrent demonstration), you might not register that an important event is taking place, and therefore not focus on it quickly enough.

What might improve the situation?

If the action is too fast, then replaying a video section in slow motion might help.

If the object started in your blind area, then using slow motion reverse play - using jog or shuttle controls - might help you follow the object back on its original trajectory.

Video in multimedia can also be backstepped in this way.

How does this affect viewing video screens?

If you have a field loss then it might be worthwhile trying out a smaller monitor. Compensating for the loss by seating position or head position could also be tried. If you have time, run through the critical sequence once with the screen in the middle distance, to get a feel for the general action - then move in close and single step it or run it slow for details.

What would improve screen access?

Preparation for the session might be the safest bet. Ideally, commentary on the video itself or reading the a transcript before the showing could alert you to the action if it is integral and important to the content of the video. If you are not sure if it is only incidental asking a friend about it should suffice.

Teachers: be sensitive to the amount of time which students might need to refocus on demonstrations, and give good and early verbal cues to upcoming events.

What names of eye conditions should I watch out for?

  • akinetopsia
  • retinitis pigmentosa (tunnel vision)
  • coloboma
  • hemianopia
  • ocular-motor apraxia (OMA).