I mentioned in a post below the overwhelming dominance of blue-ish, squar-ish icons.  It would seem that designers seem to naturally gravitate towards this particular shape/colour combination like some kind of moth to a halogen flood-light.  Allow me to demonstrate.  Below is a screenshot of one of my monitors the other day.

Now, whilst the detailed shot above doesn’t look too bad (and well done to Amazon for actually creating something that is visually distinct), in the context of an entire row of simlar looking icons, with a fair bit of visual clutter on the rest of the screen, this becomes a serious problem for pattern recognition.  Click on the screengrab or download it and view it fullsize to get an idea of the issue.  And now, let me tell you WHY this is a problem.

Cognitive psychology is that field of psychology that views the mind as an information processing system.  As such it is quite a young field but in the last 40 years or so has provided enormous insight into the internal processes of our minds.  One fundamental feature of our brains, or indeed pretty much any information processing system, is that we have capacity limitations.  We can only actually attend to, or process, or respond to so many things at once.  And these limits are known, well documented and, in most cases, pretty much absolute.  In most cases.  Ahah!  Yes, there seem to be interesting ways in which we can sidestep some of the fundamental bottle-necks of our information processing systems.  And this is where things get interesting.

In most cases, (ie: combinations of stimuli and responses) humans are observed to have a limited capacity.  Ie: the more information we are given at the same time, the more our performance decreases.  In some cases, however, we can add many, more stimuli to a given task and the processing required does not seem to increase at all – this is known as ‘unlimited capacity’ (yes, an example will follow).  Furthermore, there are a few (but so far seemingly rare) cases where it would seem that the more information we are provided with, the more effective our processing is, referred to as ‘Super Capacity’.

Let me provide you an example of unlimited capacity processing.  In fact, let’s carry out a little experiment!  Place your left hand flat on a surface next to you and raise your index finger.  Keep it there.  When you click on the link below a new window will pop up showing you an image.  Find the red ball in the image, and when you do, drop your finger to the desk.  What we’re looking to measure is how long (roughly) did it take you to find the red ball?  Ready?  Here’s the first image.

Now do the same thing again with the following image.  Got your finger ready?   Click here.

And let’s do it one more time.  Click here.

So the last image contained 560 possible targets, but it took you almost the same amount of time to find the target as when there were only 5 possible targets.  Can you see where I’m going with this?

This type of unlimited capacity is also referred to as parallel processing in that it is assumed that processing of each object happens at the same time (this is an abstract model – yes our vision system doesn’t quite work like that, but go with me here…).  So we have at our disposal well established rules of cognition and perception that can lead to massive improvements in our capacity to process information.  And do we use them?  Blue-ish, squarish icons.  Bangs head on desk.

There’s more to talk about here than I want to get into right now: parallel and serial processing, search stopping rules, Treisman’s awesome Feature Integration Theory etc… Perhaps of most relevance though, Townsend and Nozawa have developed an astonishingly parsimonious and elegant paradigm for being able to work this stuff out from a simple experiment.  Indeed this method is so effective I believe that it should be used in ALL usability testing for things like icons.  In fact even super-easy testing such as what we went through above should quickly demonstrate if your icons are distinctive enough.  Empiricism people – use it!