Other than the kapok-stuffed leather hairnets that we racers used in the '60's and '70's, all bike helmets (e.g., the popular Pro-Tec helmets) used "squishier" foam before Bell came out with their expanded-polystyrene-lined helmets. Once the ANSI (and Snell) began testing bike helmets, the helmets with spongy foam (to say nothing of the hairnets) all but disappeared from the market, since they could not meet the relevant safety standards.

Styrofoam hats, on the other hand, earn approval from the testing agencies because the EPS crushes on impact, thus absorbing energy and lessening the likelihood or severity of concussion.

(By the way: no, an EPS-lined helmet won't protect you from a hit from a speeding car. To argue, as some posters here are prone to do, that such a helmet is therefore useless for a bike rider is like arguing that steel and Kevlar helmets are useless for ground troops because they won't protect against a direct hit from a mortar shell.)

Instead of bloviating about bike helmets from his position of highly opinionated ignorance, Petersen should interview an engineer or two from Bell or Giro or one of the other current helmet manufacturers and learn a little about the subject.