The services are slowly expanding their use of "psychometric" testing to help identify who is best suited to join the military's growing cyber force.

New research is revealing an array of traits that might be linked to strong performance in cyber training schools. Solid math skills are required, but so is a knack for logic, a close eye for detail and a behavioral intuition that helps people extrapolate and predict the likely behavior of others.

And some believe there's also a correlation with musical ability.

The services are currently halfway toward their goal of assembling an operational cyber force of about 6,200 troops by the end of 2016.

In search of people with an aptitude for cyber skills to fill those ranks, the services are turning to — and in some cases creating — a battery of tests that aim to see beyond résumés and face-to-face interviews to identify the strongest candidates for an increasingly essential and distinctly nontraditional military skill set.

The most basic test is given to some recruits on day one at their Military Entrance Processing Stations. Research shows that the "cyber test," which takes about 15 to 20 minutes to complete, helps predict who will succeed in cyber training schools.

For now, it is not part of the general military entrance exam known as the Armed Services Vocational Aptitude Battery. Instead, it's given to a limited number of recruits who are on track for one of the newly created cyber jobs or specialties.

"It's primarily used to confirm and make sure you're the right fit for the job," said Donald Hill, chief of the testing division at the Military Entrance Processing Command in Illinois.

Other tests could cast a far wider net, evaluating not only people who have expressed interest in cyber careers but others across the force who might unknowingly have an aptitude for cyber warfare, according to experts inside and outside the military. Those tests are based on psychometrics and aim to measure psychological capability using questionnaires and statistical research.

The Army is trying out several versions, including personality assessments and tools that aim to measure broader cognitive abilities rather than just knowledge of a specific topic. They include some that were previously used by the intelligence community and the National Security Agency, said Army Col. Jennifer Buckner, commandant for the Army Cyber School at Fort Gordon, Georgia.

"We have a number of tests already out there," she said in an interview. "Assessing how an individual learns skills, I think those are important assessment tools that we are looking for and experimenting with. We're kind of trying to apply them in a layered approach. None of them are decisive in and of themselves. They are tools that help with our decision-making."

The Army Cyber School is also adding an "operational psychologist" to its staff to help identify how cyber students learn and work as a team, she said.

The private sector is working to develop similar tests. For example, the SANS Institute, a Maryland-based cybersecurity training center, has worked with the Army and many large corporations to craft tests that can predict success in the cyber trade.

In part, it's an effort to save money, as training programs are costly and time consuming. "They want to make pretty darn sure they have a successful candidate coming through their program," said Scott Cassity, a managing director at SANS.

Cassity said SANS has developed a test that research shows is significantly more effective at predicting success in cyber training programs compared to the military's ASVAB and cyber test.

Well-designed tests also can help with specific job assignments, for example by suggesting some cyber warriors are better suited for offensive, rather than defensive, operations.

"The way the brain works for people who can find things works a little different than for the guys who build things," said Alan Paller, the SANS research director.

Personality tests also may prove to have some predictive value, said Tom Carretta, a psychologist at the Air Force Research Laboratory who helped develop the current cyber test at MEPS.

For the past several years, the Air Force has required new recruits to take a personality test at their entrance processing stations. Using so-called big-data analytics, the Air Force might use those test results, alongside training school test scores and career information obtained later, to find unexpected traits that correlate with success in cyber fields.

"In a very large organization like the military, even these modest small increments in [predictability] can have a significant effect because we're talking about bringing in thousands of people a year," Carretta told Military Times.

It's unclear where those links might appear. A few years ago, a Google executive speaking to a conference of Army officers suggested a correlation between musical ability and the kind of math skills needed for cyber trades.

Several months later, when Buckner was reviewing a warrant officer package for a talented Army bandsman in her command, his exceptionally high military entrance exam score caught her eye.

"I actually approached the band member and said, 'Your [General Technical] scores are off the charts. I know you don't do this, but have you ever considered cyber?" Buckner recalled.

That particular soldier decided to continue in his music career, Buckner said.

But, she added, "Now I look at band members differently."