The Third Man Factor: The Invisible Presence That Walks With Climbers and Castaways in Extreme Situations

In May 1916, three exhausted men crossed the frozen mountains of a South Atlantic island on foot to save their companions. Years later, one of them wrote that during that march “it seemed to me often that we were four, not three.”

That man was Ernest Shackleton, and his sentence gave rise to one of the most striking phenomena in the psychology of extreme situations: the feeling that someone invisible is walking beside you just when you need it most.

Today it is known as the third man factor, and neuroscience has begun to understand where it might come from.

Shackleton’s march

After losing their ship to the Antarctic ice, Shackleton, Frank Worsley and Tom Crean crossed the uncharted mountains and glaciers of South Georgia in about 36 hours to reach a whaling station and get help.

In his 1919 book South, Shackleton told it like this:

“I know that 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.”

He added two details that turn the anecdote into more than a personal impression:

• He said nothing about it to his companions during the march.
• Afterward, Worsley told him: “Boss, I had a curious feeling on the march that there was another person with us.” And according to Shackleton, Crean admitted the same.

Three men, without discussing it among themselves, had felt the same impossible companionship.

From the fourth man to the “third”

If Shackleton spoke of a fourth, why is it called “the third man”? Poetry is to blame.

In 1922, T. S. Eliot published The Waste Land, which includes some unforgettable lines:

“Who is the third who walks always beside you? / When I count, there are only you and I together”

In his notes, Eliot explained that he drew on the account of one of the Antarctic expeditions, adding: “I forget which, but I think one of Shackleton’s.” In moving it into the poem, he reduced the group to two and turned the fourth into the third.

The name caught on in 2009 with The Third Man Factor, a book by journalist John Geiger that gathered dozens of similar cases.

One phenomenon, on summits, oceans and skyscrapers

The accounts repeat themselves with an eerie resemblance:

• Frank Smythe, on Everest in 1933, was climbing alone without oxygen when he felt a strong, friendly presence. When he took out a piece of mint cake, he broke it in two and turned to offer half to his invisible companion. Smythe himself suggested it might be due to lack of oxygen and stress.
• Reinhold Messner, on the descent of Nanga Parbat in 1970, where his brother Günther died, described a third climber descending with them, slightly to his right, just outside his field of vision.
• Joshua Slocum, who sailed alone around the world, said that in 1895, ill and feverish near the Azores, he saw at the helm a man who claimed to be the pilot of Columbus’s Pinta. He himself put it down to delirium.
• Ron DiFrancesco, one of the few survivors who made it out of the upper floors of the South Tower on September 11, 2001, told Geiger that when he collapsed in the smoke, a voice called him by name and guided him down the stairs.

The details change, but the pattern holds: solitude or near-solitude, extreme exhaustion, danger and, sometimes, a companion who encourages, guides or protects.

What happens in the brain

For decades, these accounts drifted between the mystical and the anecdotal. In 2006, a chance finding in a Geneva hospital gave them a neurological anchor.

The team of Shahar Arzy and Olaf Blanke was assessing a 22-year-old patient with epilepsy and no psychiatric history. When they electrically stimulated a specific area of her brain, the left temporoparietal junction, she felt that a person was standing behind her.

Most revealing was how that “shadow” behaved:

• It copied her posture: if she sat, the figure sat.
• If she hugged her knees, she felt the figure trying to grab her.
• She did not realize that the shadow was reproducing her own movements.

The researchers’ conclusion, published in Nature, was that the brain was perceiving her own body as if it belonged to someone else.

A ghost built with a robot

In 2014, Blanke and his team went a step further. First they analyzed 12 neurological patients who sensed presences and found that their lesions clustered in regions that integrate bodily signals: frontoparietal, temporoparietal and insular.

Then they designed an experiment with healthy volunteers:

1. Blindfolded, they moved a robot placed in front of them with their hand.
2. Another robot, behind them, touched their backs following those movements.
3. When the touch arrived half a second late, some participants felt that someone else was in the room. One counted as many as four “ghosts”, and two asked to stop the experiment.

The explanation, published in Current Biology, is as simple as it is unsettling: the sensed presence would arise from misattributing the source of signals from our own body. When movement and touch fall out of sync, the brain resolves the contradiction by inventing someone else.

The logic resembles that of the ideomotor effect behind the Ouija board: our own movements, attributed to an outside force.

Why it appears in extreme situations

If the sensed presence comes from a mismatch in the model of one’s own body, it makes sense that it would appear when that model is under pressure:

• Lack of oxygen, cold and exhaustion, as at high altitude.
• Sleep deprivation, like that of Charles Lindbergh, who said he felt “ghostly presences” in his cockpit after more than twenty hours of flying without sleep in 1927.
• Monotony and isolation, as in solo sailing or in isolation experiments like that of Michel Siffre, the scientist who went into a cave.

In 1987, psychologists Peter Suedfeld and J. S. P. Mocellin reviewed accounts from explorers, castaways and survivors and put forward a suggestive idea: that the sensed presence, often interpreted as a symptom, might actually be an adaptive reaction.

It is best taken as a hypothesis. No studies prove that the presence helps people survive, and the accounts have an obvious bias: only those who come back tell their story.

The presence of those who are gone

The sensed presence does not belong only to mountaintops. It appears frequently in a far more everyday context: grief.

In 1971, physician Dewi Rees interviewed 293 widowed people in an area of Wales:

• Almost half had had some experience related to their deceased spouse.
• The most common was sensing their presence, at around 39%.
• Many had not told anyone.
• Rees considered these experiences normal and often comforting.

Later reviews place these experiences at between 30% and 60% of widowed people and describe the vast majority as benign.

Here a tempting connection with attachment theory appears: the idea that, in extreme solitude or loss, the mind conjures a secure base, like the one described in secure attachment. It is a beautiful interpretation, but for now speculative: research on grief shows a more complex relationship between these experiences and the way loss is worked through.

What the third man suggests about the mind

Perhaps the most interesting thing about the third man is not the mystery but what it reveals about something we take for granted: the boundary between “me” and “someone else” is built by the brain, and under certain conditions that boundary can shift.

That this construction, when it fails, tends to produce a companion rather than a mere sensory error says something about us. We are social animals even in our illusions.

Resilience is usually described as the capacity to hold steady in the face of adversity. The accounts of Shackleton, Smythe or Messner suggest that, at times, part of that capacity might consist in not feeling alone, even when one is. Whether that companionship is a brain error or a survival strategy is a question science has not yet settled, and perhaps the answer is that it can be both at once.

Sources

• Arzy, S., Seeck, M., Ortigue, S., Spinelli, L. and Blanke, O. (2006). Induction of an illusory shadow person. Nature, 443(7109), 287.
• Blanke, O., Pozeg, P., Hara, M., Heydrich, L., Serino, A., Yamamoto, A., Higuchi, T., Salomon, R., Seeck, M., Landis, T., Arzy, S., Herbelin, B., Bleuler, H. and Rognini, G. (2014). Neurological and robot-controlled induction of an apparition. Current Biology, 24(22), 2681-2686.
• Eliot, T. S. (1922). The Waste Land.
• Geiger, J. (2009). The Third Man Factor: Surviving the Impossible. Weinstein Books.
• Rees, W. D. (1971). The hallucinations of widowhood. British Medical Journal, 4(5778), 37-41.
• Shackleton, E. (1919). South. William Heinemann.
• Suedfeld, P. and Mocellin, J. S. P. (1987). The “sensed presence” in unusual environments. Environment and Behavior, 19(1), 33-52.