I'm always looking for ways to improve the interview process, and I hit upon another interesting technique when reflecting on the qualities I am looking for in a good hire. To quickly review, these generally include:

• Enthusiasm
• Flexibility and Open-mindedness in regards to technical approaches and solutions
• General technical skill
• An intuitive sense of how things are built

Enthusiasm and Open-mindedness are easy to figure in the interview process. I have my own thoughts on how to learn about general technical skill, but on the last one, I think the easiest thing is just to ask someone to do what I tend to do on a daily basis: look at things are try to guess how they were probably built. I do this sort of reflexively; whenever I see an application, website, or any other piece of technology that does something clever or unusual, I immediately start trying to deconstruct it in the same way a kid might try to figure out how a magic trick works. Here are two quick examples that came to mind:

jacksonpollock.org - The technology is simple enough. It's clearly a flash application (if you could do this with javascript and CSS alone, that would be 100 times the hack). However, what is the algorithm that generates the paint strokes? It seems to be some combination of mouse speed and motion, as if you have a paint can from which paint is leaking at a constant rate and if you move it quickly you produce a small amount of paint per square inch, but if you leave it somewhere it will pile up. There's slightly more too it though, as it must be doing some simple physics modeling or just randomization to produce splatter.

DHTML Lemmings - Speaking of 100 times the hack, how about a full arcade game using only DHTML? I haven't really dug down into the code at all, but I can guess at how it is implemented although there are probably dozens of good ways. I would assume that the screen is composed of images rendered into divs or other containers, just like any tile-based game would be. The sprites are probably just images that are moved or altered by javascript by the game logic, and animation is a well-known javascript technique.

There are both small, fun applications that don't have any serious tricks that need to be unraveled, but the exercise is still useful. A lot of what I and others like me do really boils down to reverse engineering. Reverse engineering not in the DMCA violating sense, but in the sense of being given an application and a huge mass of code and needing to quickly understand the code by guessing at how the application is probably built and then looking for evidence that you were right.

Asking a potential hire to demonstrate their skill in this area seems very valuable, geared toward their area of expertise. A good web designer should be able to tell you how a webpage was probably constructed without looking at very much of the HTML and CSS. A good web application developer should be able to guess at the database structure, the types of objects in the system, and the types of actions being taken without looking at very much of the code. If the candidate makes wildly improbable guesses, or simply refuses to play the game, I would look elsewhere.