Refers to the reported situations where an unseen presence, such as a spirit, provides comfort or support during traumatic experiences.

Sir Ernest Shackleton, describes in his 1919 book South, his belief that an incorporeal joined him and his men during the final leg of their Antarctic journey. Shackleton wrote, "during that long and racking march of thirty-six hours over the unnamed mountains and glaciers of South Georgia, it seemed to me often that we were four, not three". His admission resulted in other survivors of extreme hardship coming forward and sharing similar experiences.

In recent years well-known adventurers like climber Reinhold Messner and polar explorers Peter Hillary and Ann Bancroft have reported the experience. One study of cases involving adventurers reported that the largest group involved climbers, with solo sailors and shipwreck survivors being the second most common group, followed by polar explorers.

Modern psychologists have used the "third man factor" to treat victims of trauma. The "cultivated inner character" lends imagined support and comfort.