I just bought a Canon Ixus 1000 HS digital camera and my favourite improvement over my old Ixus is one that you wont find amongst all of the talk of megapixels and optical zoom in the reviews – the removal of a subtle but insidious mode.

On my old Ixus, there is a button on top that switches the mode from photography to video recording.  You then press the ubiquitous button on the top right to take the photo or – if you’ve switched to video recording mode – the video.  Seems simple enough.  In fact, at first glance you might think that only a fool could get that wrong.  If you look at my video collection however, you’ll find scores of little videos that run for a couple of seconds and all share the same sound track of “huh? aarrgggghhhh!!!”.  Some of them are me, some are my wife.  I was amused to see that my parents had also amassed a collection of these little short films on a recent trip to Portugal using their identical camera.

Every time I do this I’m angry at myself for being so absent-minded and fumbling over a simple switch.  I’m sure you’re the same.  However, it occurred to me that this was in fact a text-book example of what is known in interaction design as a mode error.  Mode errors are the mistakes people make when performing the same gesture in a system (in this case pressing the take photo/video button) produces a different result depending on the mode the system happens to be in at the time.   Anyone can see with the most cursory of glances that the little switch shows the camera as being in video recording mode.  The problem with modes however is that unless the current mode is part of your locus of attention, you will make mode errors.  Period.  Its inevitable.  If you consciously work it through you are able to get it right.  But when you’re taking a photograph, your cognitive consciousness is focused on taking the shot, the timing, the composition.  Operating the camera is automated and unconscious – until you suddenly realise that there has been no click and you are staring at a little video recording icon on the viewfinder.  By that point its too late, the shot is ruined and you are the victim of yet another mode error.

Photo of my old Ixus

My old Ixus with mode selector and single button

The new Ixus has a far more elegant solution to the problem.  Instead of overloading one button with several modes, a second button has been introduced.  This is operated by the thumb and has been placed right where the button on a camcorder would be.  So rather than being just another button on a device, the placement and operation maps perfectly to the established conventions for what used to be 2 different classes of device – index finger for a photo, thumb for video.  Simple, elegant and effective – since buying the new camera we’ve not once made an accidental video recording.

My new Ixus

My new Ixus with one button for photographs and another for video

This post is heavily influenced by the late and great Jef Raskin.  I recommend you read more about modes, the cognitive conscious and automation in his classic, The Humane Interface.