Perceptual Blindness is a happening that takes place when you are being focused on one particular thing and are not noticing other happenings that are taking place and may or may not be as relevant. The thing about a human brain is that during the evolution process it has developed several features of its own. One of those would actually be the perceptual blindness phenomena. Your brain prevents itself from overloading by focusing all attention on the task you are giving it. You can be astonished with all the things that are happening all around you all the time, yet you simply are not noticing them.
Let’s take an experiment conducted by NASA for our example. Several commercial pilots were under a test which took place in a flight simulator. There were some distractions placed on the runway and the goal was for the pilots to detect these distractions. The flyers knew nothing of them, yet knew much about landings. So the amazing effect was that skilled pilots that knew the procedure by heart landed directly on the unknown distractions in 25% of cases, due they were focused on the procedure itself, as they’ve thought that these skills were at test then. And yet all freshmen pilots that had lack of experience have been noticing the distractions in almost every case. They were not focusing on particular procedures at all, due the fact they did not know them well. So right about now I think you are guessing where all this is headed.
How does this affect testing?
You can miss lots and lots when are focusing on separate details. Just think of how many times have you been going through the whole software structure looking for a particular bug or something of that kind?
Let’s look through a simple case example. Your tester is testing a website. His goal is making sure that the design is done well and everything matches the blueprints. So far so good. He will definitely be looking for all kinds of flaws in spacing etc. yet will he notice some typos or a wrong URL structure. Not so plausible. Thus you may end up with an URL that is leading to yourwebiste.com rather than to yourwebsite.com. And the tester will not be to blame, he did his job fine.
So how can your teams deal with this phenomena?
- Testing can be done in pairs
- The communication has to be improved. It should, by the way, always be amongst the top criteria.
You can have some cross-functional teams.
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