According to a little anecdote from director Gore Verbinsky, director of the first three "Pirates of the Caribbean" films
Geoffrey Rush (better known as Captain Hector Barbossa) was aware of the fact that, in the Western world, viewers habitually follow a film by looking at the screen from left to right, just like books.
In the scenes he always tried to stand on the left side of each frame to keep the audience's attention on his performance.
His attempts increased in intensity during the scenes he shared with Keira Knightley and the monkey.
The reason? According to the director, the answer was: "I'm sharing the frame with a beautiful actress and a very nice monkey... who would ever look at me?"