10284
When trained with positive reinforcement , rats can learn to respond to a signal of a certain duration , but not to signals of shorter or longer durations , which demonstrates that they can discriminate between different durations .
 rats
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: media, plant, vehicle, astronomical object, time, disease, animal, location, person, organization, mythical figure, food, biology, geographical phenomenon, instrument, event 
Text: {0} 
Answer:
 rats