The illusion of vision

What we look at and what we see can be completely different. Our perception is filtered by what we think we know, past experience and expectation. Indeed this is what the brain does before creating a plausible image. When we are looking at an animal in a cage we do not think ‘there is a series of segments of a lion’ when the bars are positioned in front of the animal. No, the brain creates an experience of a lion. Equally, if we have just watched a spooky film and on taking the rubbish out into the alley we see a moving shadow we are more likely to believe that it could be an intruder rather than a cast of a branch.

In the world of neuroscience, all conscious experiences are created by the brain including vision and pain. The world that we see in front of us is no exception, however it is entirely possible that we can miss something right befroe our very ‘eyes’ if the brain does not perceive it to be there or happening. Christopher Chabris and Daniel Simons explain this brilliantly in their book that discusses the illusions of vision, memory and knwledge amongst other functions that we take for granted. Daniel Simons is known for a famous experiment that you can do here:

Have a go and see how you get on. Then ask friends and family! It helps to explain how we can be falsely secure in what we see, know and experience.

The illusion of vision is relevant to daily practice with patients in pain for several reasons. Firstly it demonstrates how we must be targeting the brain and the processing of information to change someone’s experience of their pain and secondly how we can use vision and illusion to ‘train the brain’. In simple terms, the brain is operating in a particular mode or state that is giving the current experience of the body and mind that could include pain.

To alter this experience we need to give the brain something else to do that has meaning and purpose. Of course, the meaning will need to be personal and contextual to that person but could include a position change, an exercise, a change of thought, writing a poem or drawing a picture. Treatment-wise we think about the types of intervention that could either change the flow of informatioin into the brain or to stimulate descending pathways that runs from brain to spinal cord and dampen the activity here in the dorsal horn.

In brain training we are focusing upon particular changes that we know take place in the brain termed cortical plasticity (click here, here and here). This includes the Graded Motor Imagery programme (and click HERE) that we use as part of the treatment programme and training for CRPS and other conditions.

If we are living in an illusion, which many of the leading lights in the field of neuroscience are saying, then this is still our experience and our ‘illusion’. Modern rehabilitation is not only about developing health and function in the tissues, but also changing the brain so that the sense of self is normal in terms of ‘feeling’ the body and in controlling movement. Both of these are developed through redefining the sensory and motor maps that change when we are in pain and not moving properly. Only in achieving this will nomal service be restored in function, confidence and longevity.

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