|InfoVis.net>Magazine>message nş 92||Published 2002-06-24|
|También disponible en Espańol|
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I propose to you a brief but interesting experiment. Watch the centre point lying between the three yellow dots, trying to concentrate on the movement of the blue dots.Â
If you have a little patience, one, two or even the three yellow dots will disappear in front of your eyes for a while, reappearing from time to time.
This phenomenon is called Motion Induced Blindness (MIB) and has been described thanks to the work of professors Yoram Bonneh, Alexander Cooperman and Dov SagiÂ that published their work last year in the prestigious scientific journal, Nature.
It seems that the brain has different â€śtheoretical modelsâ€ť about the appearance and nature of the world that surrounds us. Usually sensorial stimuli allow the brain to select one of them, but in certain situations, like the one seen before, several models enter into conflict and the brain cannot decide on only one of them.
According to John Witfield the researchers speculate about whether this phenomenon appears in real life without us noticing it. Maybe for some night drivers the red lights of the preceding cars could disappear temporally while he/she is paying attention to the moving lights coming from the other lane.
Other scientists, like Jack Pettigrew from the Queensland University at Brisbane (Australia) have achieved similar effects by applying selectively electromagnetic impulses to one or the other cerebral hemisphere.Â
It seems that the left hemisphere suppresses the sensorial information that the right hemisphere owns if it does not match with the theoretical model it has selected. This way we could say that the right hemisphere sees the world as it is and the left hemisphere sees the world as it believes it looks like.
The fact that people that have suffered from certain injuries in the right side of brain consistently deny their evident paralysis or see their own legs disappear strengthen the foundations of this theory.
All this makes me think about the relevance of mental models, since Visualization is â€śthe formation of a mental image of a conceptâ€ť (see the Glossary)
Barbara Tversky** introduced the concept of Cognitive Map to refer to the mental model and the internal representation of reality in a structured way. In the same way that a real map can be consulted and inspected, mental constructions of cognitive maps can be [mentally] inspected as well.
Tversky speaks about the â€śCognitive Collageâ€ť, the set of cognitive maps that we use to approach reality. For example I can have in my mind different cognitive maps of the bus lines of my city. Some of them are clearer than others, belonging to lines I use more frequently. The existence of this collage leads to conflict when two different maps overlap on the same problem the brain is trying to solve. As in the case of the blue and yellow dots.
An example that may also be relevant, is the existence of different navigation models coexisting in the same web site. If they arenâ€™t complementary and clear they can lead to confusion instead of clarification, since itâ€™s very difficult to get a mental image of a web site, due to the high non linearity of this medium, where you donâ€™t have physical references helping you to incorporate its structure. In the end you are always placed in what seems like a unique, stand alone page.
The lack of a solid theory of the process of formation and use of cognitive maps in the understanding of things prevents us from giving easy â€śrecipesâ€ť to the information designer.Â
Nevertheless knowing of its existence should serve to open up our mind. We donâ€™t always see whatâ€™s in front of our noses.
We thank Prof. Bonneh for the kindness of allowing us to use the image of this issue.
*Â Â Motion Induced Blindness in Normal Observers, Nature, 411, 2001, pp 798-801.
At the page on Motion Induced Blindness you can get more information on this phenomenon.
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