In 1994, Donna Good Higbee began an investigation into HSII (humanspontaneous involuntary invisibility). In every HSII case she hasresearched, the person is physically still present, although unable to beseen or heard. From the point of view of the invisible person, the worldlooks normal and they have no idea that they cannot be seen or heard bypeople around them. Donna continues to receive reports of human spontaneousinvoluntary invisibility.