What's the main purpose of the baseline test in Blade Runner?

Question

In Blade Runner 2049, officer K (a Replicant) is made to take a 'baseline test.

What's the point in repeating what the machine says in his baseline test?

Answer 1

To gauge K's reaction time and emotional response

The baseline test is self-explanatory; K has set a baseline response to this particular set of questions, the tester checks them and makes sure that he is aligned to it.

We have two examples of K taking his baseline, both with varying and telling signs. From them we can gather that the purpose is two-fold:

1. To gauge K's reaction time

   In the first test, K responds to his cues almost perfectly. There's only a single mention of a moment's hesitation, but he seems to pass the test with what seems to be flying colours:

   INTERVIEWER (O.S.)
   Do you long for having your heart
   interlinked. Interlinked.
   K
   Interlinked.
   INTERVIEWER (O.S.)
   Do you dream about being interlinked?
   Interlinked.
   A moment’s hesitation. Then --
   K
   Interlinked.
   INTERVIEWER (O.S.)
   What’s it like to hold your child in your
   arms? Interlinked.
   K
   Interlinked.
   _{-Final Shooting Script (undated), Blade Runner 2049 (2017), Fancher, H. and Green, M.}

   At which point he is almost immediately cleared and allowed to take his bonus:

   INTERVIEWER (O.S.)
   Say that three times. Within cells
   interlinked.
   K
   Within cells interlinked. Within cells
   interlinked. Within cells interlinked.
   A pause, a grinding of unseen machinery, the camera powering
   down, then --
   INTERVIEWER (O.S.)
   (kindly)
   We’re done. Constant K. You can pick up
   your bonus.
   K’s eyes look to the eye of the camera.
   K
   Thank you, Sir.
   _-Ibid.

   Now compare that to his second baseline toward the end of the movie:

   INTERVIEWER (O.S.)
   What’s it like to hold the hand of
   someone you love. Interlinked.
   A pause.
   K
   Interlinked.
   
   ...
   
   INTERVIEWER (O.S.)
   Dark.
   K
   Dark.
   INT. JOSHI’S OFFICE. POLICE STATION. INTERCUT.
   ON JOSHI. Watching K’s FEED carefully, knowingly. She can
   sense a change in him, as --
   INT. INTERVIEW ROOM.
   INTERVIEWER (O.S.)
   Within cells interlinked.
   K
   Within cells interlinked.
   INTERVIEWER (O.S.)
   Within one stem.
   K
   Within one stem.
   INTERVIEWER (O.S.)
   And dreadfully distinct.
   K
   And dreadfully distinct.
   INTERVIEWER (O.S.)
   Against the dark.
   K
   Against the dark.
   INTERVIEWER (O.S.)
   A tall white fountain played.
   A pause. K looks at camera.
   K
   A tall white fountain played.
   A pause.
   INTERVIEWER (O.S.)
   You’re not even close to baseline.
   INT. JOSHI’S OFFICE. POLICE STATION. MOMENTS LATER.
   K is seated, looking off. A new energy to him. The
   entitlement that comes from knowing. Joshi enters, pissed.
   JOSHI
   The hell is with you?
   -Ibid.

   K's noticeably slower and more affected by the questions.

2. To gauge K's emotional response

   It's not a wonder that the questions themselves are designed to elicit some emotional response out of him. Have a look at the distinct questions:

   • Have you ever been in an institution?
   • Do they keep you in a cell.
   • When you are not performing your duties do they keep you in a little box?
   • What’s it like to hold the hand of someone you love.
   • Did they teach you how to feel, finger to finger?
   • Do you long for having your heart interlinked.
   • Do you dream about being interlinked?
   • What’s it like to hold your child in your arms?
   • Do you feel like there is a part of you that is missing?
   • What’s it like to be filled with dread?
   • Do you like being separated from other people?

   [all extracted from the script]

   I mean, no one with real human emotions can withstand themselves from reacting to those questions. You can see above that K's emotions go rampant at the mention of closeness and connection (which these Replicants are supposed to be made distinct from).