Why does your cat paw at the door? Because it works. You immediately know she wants to go out, so you open the door. This action rewards your cat's efforts. Or, if she keeps at it enough, she may manage to open the door on her own – again, a reward.
The door-pawing cat is sometimes used in psychology classes to illustrate the reinforcing power of continuous versus intermittent reinforcement of a behavior. A cat that paws at a door and is rewarded every time by having the door opened is on a "continuous schedule" of positive reinforcement. But, if the owner suddenly stops responding to the cat's pawing the door, the cat will soon discontinue the behavior.
The formula is:
Used to work + Doesn't work anymore = Quit.
However, if a door-pawing cat is rewarded for the behavior intermittently and randomly (sometimes you open the door, sometimes you don't), she will not give up so easily because she always thinks that the reward might be forthcoming the very next time.
The formula becomes:
Sometimes works + Isn't working now = Better keep at it for a while longer.
This is the power of intermittent reinforcement, which, incidentally, is the driving force behind gamblers' optimism that next time will be the time to win the jackpot. Of course, even a cat that was intermittently rewarded will eventually quit if there is no reward after numerous attempts.
Some cats learn to open doors on their own, perhaps inspired by frustration at a barrier that separates them from something they want. One of my cats, Monkey, who lives and dies for food, spent months watching me open the ground level door of the food cabinet at meal times. Then, one memorable day, she started taking matters into her own paws, scratching at the handle-side of the door, seemingly copying my behavior or intuitively pawing at the door in hopes that it would open.
No doubt she was not immediately successful, except in the sense that the spring-loaded door may have opened a little wider during some of her vain attempts. Eventually, her efforts were rewarded when the door flew completely open, giving her access to a veritable cornucopia of cat food. I was forced to move the food to another cabinet if I was to avoid her gorging herself daily.
Soon she shifted her attention to the door of the new storage cupboard – not that this new obsession stopped her from continuously opening the door to the original cabinet just in case there was food inside. I observed her strategy and her perseverance on some occasions. She would paw at the door; it would open a smidgen and then snap back. She would then pull the door open a little further and, once again, it would snap back. This procedure was repeated a dozen times or more but then the door opened past a critical point and remained open. Talk about intermittent reinforcement.
I've had to move the food supply to the bottom half of a double oven that has a heavy metal spring-loaded door. Monkey can't get this door open because it is physically impossible for her to do this, but she has learned that small pieces of kibble that occasionally get caught in the hinge can be released by pawing – so now you can guess what she spends her time doing after feeding time. When incredibly hungry, she returns to cabinet one and then cabinet two and opens the doors just in case she's in luck.
My other cat Cinder has different priorities but also learns what works fairly quickly. Her favorite pastime is a brief, chaperoned walk outside to "smell the roses," chew on some grass, and roll in the dirt. The door between her and utopia is a fly-screened kitchen slider that she has watched me open on numerous occasions. Whether through observational learning, frustration, or trial and error, she eventually learned to open the slider by pawing it. The freedom she obtained in this way was, for her, the most potent reward of all.
I was shocked when I discovered that the door had "opened itself" and both cats were outside grazing on my lawn. My solution was to put a catch on the door and hope that Cinder's attempts to paw and claw the door open would be short-lived once she discovered the futility of her actions. No such luck. Cinder tried to open the door many times before eventually giving up.