A little more context
In the 2000 study, 15 Cornell undergraduates wore the shirt, which pretest interviews suggested most students would be embarrassed to wear. On average, the wearers estimated that 46 percent of the observers could name who was pictured. Only 23 percent could: half as many.
In a later study in the same paper, people in group discussions overestimated how much their own contributions, good and bad, stood out to the others. The authors note that this does not make people wholly inaccurate about the impression they make. These were laboratory studies, mostly with university students: the spotlight is dimmer than it feels, not switched off.