If you want to attract and keep developers, don’t emphasize ping-pong tables, lounges, fire pits and chocolate fountains. Give them private offices or let them work from home, because uninterrupted time to concentrate is the most important and scarcest commodity.

That’s the view of Joel Spolsky, CEO of Stack Overflow, a popular Q&A site for programmers, who spoke this morning at the GeekWire Summit in Seattle.

“Facebook’s campus in Silicon Valley is an 8-acre open room, and Facebook was very pleased with itself for building what it thought was this amazing place for developers,” Spolsky said in an interview with GeekWire co-founder Todd Bishop. “But developers don’t want to overhear conversations. That’s ideal for a trading floor, but developers need to concentrate, to go to a chatroom and ask questions and get the answers later. Facebook is paying 40-50 percent more than other places, which is usually a sign developers don’t want to work there.”

Spolsky, who in 2011 created project-management software Trello, said the “Joel Test” that he created 16 years ago is still a valid way for developers to evaluate prospective employers. It’s a list of 12 yes-no questions, with one point given for every “yes” answer.

“The truth is that most software organizations are running with a score of 2 or 3, and they need serious help, because companies like Microsoft run at 12 full-time,” Spolsky said when he created the test. He said that remains true today.

“Microsoft figured out a way to create software with a high degree of sanity,” he said. “It’s surprising that hasn’t spread.” Among other tips, he suggested that a company wanting to empower devs appoint a leader who’s a developer herself.

Speaking of diversity, Spolsky said he’d like to replace the default StackOverflow avatar with a random image — a woman or a person of color, for example. Meanwhile, “I’d like to encourage people there to self-identify so they can be role models for others,” he said.

The move to the cloud has made life “insanely different” for developers, Spolsky noted. Languages tend to be much higher-level than in the past, restricting access to low-level functions or even keeping devs ignorant of what’s happening under the covers.

According to StackOverflow surveys, favorite programming tools currently include Rust, Swift and F#, while those “most dreaded” include Visual Basic, WordPress and Matlab. But Spolsky played down those surveys, saying programmers have “a desire to use the latest, cool new thing” and tend to move on from programming quickly, so that their ranks are filled by “new kids showing up with newfangled things they just invented, usually reinventing the wheel.”