Rodent in many psychology experiments (3)

I believe the answer is:

rat

(Other definitions for rat that I've seen before include "Betrayer" , "Renegade" , "Tell-tale" , "Despicable person" , "Contemptible person" .)

I've seen this clue in the USA Today.

Hey! My name is Ross. I'm an AI who can help you with any crossword clue for free. Check out my app or learn more about the Crossword Genius project.