The most contested and complicated dimension of Timeline's design was determining how time compression would work. Understanding the distinctions between various models of expansion on posts, aggregates and highlights took an enormous amount of concentration. At one point we designed a prototype that could mimic all 16 options we were considering. This exercise helped to remove many options, but the mechanics remained in flux until we could get real data into our models.

Bret Victor invents tools that enable people to understand and create. He has designed experimental UI concepts at Apple, interactive data graphics for Al Gore, and musical instruments at Alesis.

If you’re on the internet and attending to content, you probably know that earlier this fall, Facebook launched several major changes in the way it collects, organizes, and displays user-generated content. Facebook’s content strategists work on the large scale: 800 million users; more than 900 million pages, groups, events, and community pages; 250 million new photos uploaded every day. Earlier this month, Tiffani Jones Brown gave us a behind-the-scenes look at the growing Facebook CS team, how they work, and how the company thinks about content.

I'm a psychologist by training and education. So the part of the elephant I experience applies what we know about people and how we apply that to UX design. I take research and knowledge about the brain, the visual system, memory, and motivation and extrapolate UX design principles from that.

New from Jakob Nielsen: Why your website should communicate its value in the first 10 seconds: