Say your guinea pig bites you, for whatever reason. If you scold it, and point and yell 'NO BITE! ! 'or' NOO 'when they look up at you, can they understand that they did something bad like dogs can if you yell at them? My guinea pig I think likes me since I've taken good care of him since I got him in early July (cleaning his cage daily, feeding him lettuce, giving him attention ect),, but I don't think he likes it when I clean his cage, especially certain areas of the cage, so yesterday he bit me when I put my finger near his mouth. I didn't think he'd do it hard but he kinda did to the point there was a little indent in my skin.

If you yell at him (not scream but firmly) , can that help?

No never punish a guinea pig, there is no way it would understand what and why you did it, it would only feel battered and shamed. Most often when a guinea pig bites you like yours did it is because your finger smelled like food and it thought it was getting something to eat and not until it lobed on will did it realize it was not food.

If you do have a biter however, there is a way to stop it from biting. My Sally was a biter because she had been abused before coming to me.Every time she bit be i would pick her up and kiss her on the mouth and cuddle her. It took her 6 weeks to realize that her mouth was for kissing not for biting and when she did she crawled up my chest and kissed me for 1/2 hour, it was adorable. Keep in mind a guinea pig kiss is a soft nibble on the lips or the tip or your nose.

30 years dedicated to caring for and loving guinea pigs

No. Guinea pigs will not understand, they are not smart enough so you should not scold them. If he doesn't like it when you clean his cage you could put him in a box for 15 minutes (Somewhere safe with food and water) while you clean it, he probably feels territorial about his cage and wants to protect it. He doesn't understand that you are trying to help him by cleaning it.

Have had pet guinea pigs for many years, have studied animal behaviour at university, and work in a wildlife park.

No, they don't 'understand,' they are animals that respond to stimulus by instinct. Bad noise, react to flee or fight, good noise, pleasure. They also have instinct about what they do or don't like, but their actions and responses are based on their needs and you can train them to respond in a specific way.

It could work. But somehow, I think your pet will just get scared. A good tactic to try out is by giving them treats when they are good. When they bite you or whatever, don't give him any treats for the day. Eventually, he will get your drift and be a darling little angel ... Hope so!: -)