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"Unbelievable! You, [Subject Name Here], must be the pride of [Subject Hometown Here]."

A Test Subject is a human, animal or robotic individual used by Aperture Science in their computer-aided Enrichment Center.



Test Subject Chell, Portal's playable character.

  • While most of the time Test Subjects are human individuals, Aperture has been known to use animals (such as chickens), as well as robots (such as ATLAS, P-Body and the Military Androids).
  • Test Subjects are also required to answer essay questionnaire, like Essay Question 1-A: "Why should Aperture Science accept you as a research volunteer and would anyone file a police report if you went missing?"[3]
  • While common scientific / medical research made on humans is never directly dangerous, the ASHPD tests can be very dangerous, and can often result in the death of an unwary Test Subject. The hazards met include vaporization caused by High Energy Pellets, death by bullets from Sentry Turrets, falling in toxic liquid, being burned alive (by falling in an Emergency Intelligence Incinerator, or, in the case of Chell, by being purposefully killed by GLaDOS), being hurt by falling objects such as Weighted Storage Cubes, and being crushed by pistons (only in maintenance areas, if the Test Subject escapes).
  • Human Test Subjects are fitted with Advanced Knee Replacement to slow down their falls, primarily to protect expensive testing equipment rather than the Test Subjects.
  • According to GLaDOS, Aperture Science's annual bring-your-daughter-to-work day "is the perfect time to have [one's daughter] tested", suggesting Test Subjects are (at least partially) chosen among daughters of Aperture employees. Other popular Aperture Science Test Subject gathering methods include paying homeless people insignificant wages, forcing employees to participate in tests, picking up orphans from orphanages or transferring psychiatric patients from Aperture-branded mental institutions. Compared to early testing phases, when Aperture seems to have hired the best of the best (such as "astronauts" "war heroes" and "olympians"), Aperture later shows both increasing issues with test subject quality and apparent investigations into the whereabouts of failed test subjects.
  • ASHPD tests allowed Aperture Science to discover that Test Subjects, when confronted with science, may exhibit any or all of the following personality flaws: cowardice, impaired motor skills, poor judgement, fear of heights, weights, depths, bullets, and fire.[4]
  • According to Wheatley in Portal 2, the Enrichment Center has held over 10,000 test subjects.
Test subject

The panel on the back of a Relaxation Center room that labels the test subject.

  • When Chell was moving from the Relaxation Center room to the docking station and her room was slowly being destroyed, you can see other subjects' Relaxation Center rooms and a small description about the subject such as their age, body type, gender, and height. However, it seems most of these test subjects have "expired" according to the label.

Known Test Subjects[]

Aperture clipboard 042

Test Subject #042's clipboard sheet.

As of the events of Portal 2, both Wheatley and GLaDOS imply that Chell is the last surviving Test Subject of the 10,000 residents that were stored there before the enrichment center was locked down. Shortly before GLaDOS' destruction at the hands of Chell, a robotic replacement program was being developed to render Chell and any human-based test subjects as unnecessary and irrelevant. However, during the co-op campaign, ATLAS and P-body discover a room full of humans in suspended animation, apparently giving the facility even more subjects to test. However, these test subjects die as well due to a system malfunction caused by a bird.

Behind the scenes[]

  • In Portal and Portal 2, the playable characters are always Test Subjects.
  • In the original Portal trailer, the "Portal is Free" video, the Portal 2 diagrams, the Portal game cover, and several signs seen in-game, Test Subjects are always represented as genderless black stick figures.


  • The track "Subject Name Here" in the Portal soundtrack is a reference to the GLaDOS' quote, "Unbelievable ! You, [Subject Name Here], must be the pride of [Subject Hometown Here]." said at the completion of Test Chamber 06.
  • During the credits of the multiplayer campaign, GLaDOS lists a fault with a number of the test subjects (or Valve employees). When scrolling over Gabe Newell's name GLaDOS titles him as a procrastinator; a common joke with Valve's tardiness in releasing games.

List of appearances[]


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