"The Human Factor" is an episode of the original The Outer Limits television show. It first aired on 11 November 1963, during the first season. The title was re-used in 2002 for an episode with an unrelated plot.

Doctor James Hamilton develops a device that allows him to experience the thoughts and feelings of another person.

At a military outpost in Greenland, Project Engineer Maj. Brothers (Guardino) begins losing his grip on reality - while wrestling with guilt and remorse - after losing one of his soldiers in an icy crevasse. Mentally haunted by a spectre of the dead man, Brothers decides he must detonate an atomic device to obliterate the crevasse, along with any implicating evidence of self-imposed incompetence - and the outpost, as well - to purge himself of his emotional anguish. The outpost's psychiatrist, Dr. Hamilton (Merrill), uses a revolutionary mind probe machine in an attempt to understand what is driving Brothers mad. During the experiment, Hamilton learns of the officer's plan to destroy the outpost as their minds join for a split second. When an unexpected earthquake causes the device to malfunction, the minds of Hamilton and Brothers are switched. This new identity enables the insane officer to set about his plan for destruction while in the guise of the doctor, with the real doctor - now in the guise of the disturbed officer - confined to a padded cell, desperately trying to warn everyone of the impending doom. When Hamilton's administrative assistant, Ingrid (Kellerman), who had earlier expressed her love for the doctor, reads his notes that were taken prior to the experiment, she learns of the possible exchange of minds between the two men. Ingrid then comes by the cell to talk with Brothers about his claims of really being the doctor, where he convinces her that he is actually the man she loves by revealing an intimate detail regarding their relationship; something that the officer would know nothing about. Now realizing that the wrong man is behind bars, she helps him to escape. Meanwhile, attempting to obtain information from another officer on how to detonate the bomb, Brothers is ordered to return to the doctor's office, where he encounters Hamilton and Ingrid. Brothers, intent on killing Hamilton before he can expose his true identity, is mortally wounded during Hamilton's attempt to attach the electrodes from the mind probe machine - with help from Ingrid - to himself and to Brothers. At the final moment of the process, just before Brothers dies, Hamilton's mind is successfully returned to his body. Afterwards, both Hamilton and Ingrid try to make sense of the ordeal, while wondering how to explain the unbelievable circumstances surrounding Brothers' death, with Hamilton suggesting that they simply tell the truth - Maj. Brothers shot himself.

...
Wikipedia