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If you have had to catch a taxi recently, you may have noticed how reliant many of them have become on their satellite navigation systems. While inherently useful to have a visual map showing your progress to your ultimate destination, I find myself as a passenger sometimes almost mesmerised by the moving image as we trundle along.

(Gosh, and I remember a time when cab drivers would actually know their way around our cities without a map. Is this all the result of outsourcing our mental capabilities? But I digress…)

So, if I as a passenger am finding myself distracted by the image, what effect is this having on the drivers themselves?

There is a wonderful classic experiment called  “The Invisible Gorilla” which demonstrates beautifully how when we are paying attention to something, we become blind to what else is going on in our environment.


In this experiment you are asked to concentrate on two teams playing basketball and to count how many times the ball is passed to the team in white. Simple huh? Yes, and whilst you are busy paying close attention to the ball. You don’t notice the gorilla walking across the play area. Try it yourself and see.

Even though I know the experiment well, I can still fool my brain into “not seeing” the gorilla by focussing hard. This effect is called “inattentional blindness” and yes we are all guilty of it.

So what has this got to do with navigational systems?

Well, it appears that if you are trying to hold an image in your mind of a road map, it produced the same inattentional effect. In other words it makes you ignore what else is going on in front of you, which if you are driving means you no longer “see” the other vehicles, cyclists or pedestrians.


It’s because our brain has a limited capacity to process information – a neural bottle- neck is created.


Bioscholar recently reported on a 2012 study undertaken at the University College London, where a group of volunteers were shown images of different coloured squares and while holding them in their mind, told to expect to see a flash of light.


Even though they had been told to expect to see the flash, the subjects were less likely to recall seeing it when holding the mental images of the squares in mind, than when they weren’t being asked to.

The researchers used neuroimaging to demonstrate that when the subjects were holding onto their mental images, they showed less activity in that part of the brain dealing with processing other incoming visual information.

The bottom line is that even though you are awake and looking, you may not “see” other things around us whilst holding an image of a road map (or any other image) in your mind.

I might start asking taxi drivers to turn off their “sat navs when” I hire them, it could keep us all a lot safer on the roads. What do you think?



Visual Short-term Memory Load Reduces Retinotopic Cortex Response to Contrast

Nikos Konstantinou, Bahador Bahrami, Geraint Rees, and Nilli Lavie

Journal of Cognitive Neuroscience 2012 24:11, 2199-2210 doi: 10.1162/jocn_a_00279




Dr Jenny Brockis

Dr Jenny Brockis is a medical practitioner and internationally board-certified lifestyle medicine physician, workplace health and wellbeing consultant, keynote speaker and best-selling author. You can now pre-order her new book ‘The Natural Advantage’ due for publication in October 2024.

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