Participation in the experiment is mandatory. Failure to follow instructions will result in your immediate incarceration.
The Professor

The Professor's Experiment is an elaborate multi-phase experiment that involves surveilling unwilling subjects and pushing them to their limits. The experiment began shortly after the murder of Beacon Heights University student, Nolan Hotchkiss. If the subjects refuse to comply they will be incarcerated for conspiracy to cover up a crime.

The experiment is currently navigated by The Professor.

The Beginning


Phase One

Phase One appears to have been mostly surveillance on The Perfectionists, Alison DiLaurentis, and eventually Taylor Hotchkiss with the assistance of Jeremy Beckett. Beckett surveilled the group in order to protect Caitlin.

The Professor hacked into Beacon Guard and other systems to spy on and threaten the group while seeing what they would do. They also made an encrypted list using Mona's Crystal Ball (Beacon Heights Success Predictor) so that the system could pinpoint specific people which included Taylor Hotchkiss and Ray Hogadorn.  In the episode, The Ghost Sonata, Taylor mentions that she believes her mother used Mona's program to find Alison so she could find Taylor as she doesn't believe that she's dead. This use of psychological profiling wasn't intention of the program, which is to identify similar personality traits in people. The Professor used Mona's program in the same way for their experiment as Caitlin, Alison, Ray, Ava, Dylan, Mona and Taylor, seem to share a similar psychological pattern that is perfect for the Professor's criteria.

Jeremy was surveilling The Perfectionists, Alison and Mona the whole time to protect Caitlin. He destroyed his unusually military-grade encrypted personal computer by drilling a few holes into it and tossing it into the river as it was the Hotchkiss device that was used to cause the timed Beacon Guard blackout on the night Nolan was killed. The laptop may have had files that had surveillance footage of The Perfectionists, Mona and Alison for The Professor's experiment because of the amount of encryption on the computer, which may have been provided by The Professor.

Jeremy tried to cover up his tracks and make a run for it but, everyone believing he killed Nolan, was shot by Taylor and The Professor caught it all on camera. With incriminating evidence against them, they decided it was time for Phase Two.

Phase Two

In a room with seven chairs at Watchgrove Hall, The Professor introduced the subjects to the experiment and ensured their compliance by destroying Taylor's RV and personal Beacon Guard computer, which eliminates the perfect way to find out who The Professor was.

He also asked them to tell him their greatest fear for yet undisclosed purposes that may include psychological warfare against The Perfectionists, Mona and Alison as plans for their tests in The Experiment: Phase Two.

Their fears are the following:

  • Alison DiLaurentis - "I'm afraid I'm too broken to be fixed"
  • Caitlin Park-Lewis - "I'm afraid I'll fail, not just at school, but in life"
  • Ava Jalali - "I'm afraid I'll become like my father"
  • Dylan Walker - "I'm afraid I'll have to go home"
  • Mona Vanderwaal - "Dying before I find out who you are, bitch!"


Full Name Phase Involved Role in the experiment Status
Nolan Hotchkiss Phase One Murdered by the Professor to initiate the experiment Purpose Served: eliminated
Jeremy Beckett Phase One Surveilling Ava, Dylan, Mona, and Alison to protect Caitlin. Purpose Served: eliminated
Caitlin Park-Lewis Phase One & Two Subject
Served as motivation for Jeremy
Ava Jalali Phase One & Two Subject Active
Dylan Walker Phase One & Two Subject Active
Mona Vanderwaal Phase Two (Wasn't under surveillance for Phase One) Subject Active
Alison DiLaurentis Unclear Subject Active
Ray Hogadorn Unclear Unknown (Was on list created by The Professor) Active
Taylor Hotchkiss Unclear Unknown (Was on list created by The Professor) Active

Notes and Trivia


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