On Saturday September 17 1994 at 7:00 p.m. a collaborator and I blindfolded each other. He rode a tricycle up and down the street (parallel with the street) and I walked back and forth across the street (perpendicular to the street). He struck my left knee with the tricycle handlebars at 7:48 p.m. At 7:49 p.m. we changed roles so I was riding the tricycle up and down the street and he was walking back and forth across the street. Although the front wheel of the tricycle broke off when I ran into the curb, I eventually bumped into him on foot at approximately 9:18 p.m.