[lsiebert]

A few suggestions.

I'd avoid a maximal test as a basis for your decision. It's fine to test to make sure a potential intern has the technical knowledge to succeed, but studies have shown that given a familiarity with the subject, real world ability is largely not correlated with being able to do really well on a test of how fast/smart they are on a test. What seems to be a good predictor is something called grit... Basically how well a person deals with setbacks, keeps moving, perseveres etc. You should ask about setbacks and challenges they have faced and how they dealt with them.

I recall that there are grit assessment tools like questionnaires; I know West Point recently began to use one for it's cadet applicants. There may be one available online.

Remember that good hackers may be introverted, shy, or lack social skills. People have inherent biases against such people, tending to think of them as less intelligent and capable. Also remember that people have a bias and will rate more attractive people as smarter, more competent etc. Try to be aware of these inherent biases. so you pick the best candidate on their ability and merits.

Hope that is helpful.