One of the Cognitive ghosts discussed in the The Rest Is Science episode “Cognitive Ghosts”.
What it is
The Third Man Factor is the powerful, comforting sense of an unseen presence — an extra companion walking beside you — that often appears to people under extreme physical and mental stress: mountaineers near the summit, polar explorers, shipwreck survivors, 9/11 escapees. The presence is typically benevolent and sometimes seems to guide the person to safety.
What’s happening in the brain
It’s thought to be a glitch of the temporoparietal junction (TPJ) — the region that builds your sense of where your own body is in space. Under extreme stress, fatigue, cold, and low oxygen, the brain’s model of “self” can split: proprioceptive signals about your own body get misattributed to a separate entity, and the brain, unable to reconcile them, defaults to “there must be someone else here with me.” It’s the same self-model that, when disturbed, produces out-of-body experiences.
References from the show
- The phenomenon is named after T. S. Eliot’s The Waste Land — “Who is the third who walks always beside you?” — which Eliot footnoted as inspired by Shackleton’s Antarctic crossing. Other famous cases: Frank Smythe sensing a companion near the summit of Everest (~28,000 ft).
- Book: John Geiger, The Third Man Factor: Surviving the Impossible (2009) — compiles dozens of cases.
- Olaf Blanke and colleagues at EPFL (Lausanne), 2014 — “Neurological and Robot-Controlled Induction of an Apparition” (Current Biology). Using a robot that poked subjects’ backs with a ~500 ms delay relative to their own hand movements, they induced a felt presence in healthy volunteers in the lab — strong evidence the “ghost” is a self-model error, not a visitor.
Links
Related
- Sleep paralysis — felt presence at the edge of sleep
- Blindsight — body reacting to what the conscious self can’t place
- End-of-life dreams and visions — presences perceived near death
- Cognitive ghosts