Every night we cuddle with the pups up in our room, on the family bed. (It's why we have a king sized bed, after all!). The dogs come up via a set of 'stairs' Tom created for them. Someday we'll get real stairs. Thing is, both Olive and Chester need the stairs. Olive is too small to just jump up on the bed...and Chester just doesn't have a clue how to 'jump' up on the bed. Emily...she can bound across the room to land on the bed in one leap. And does so, often!
Since Emily believes SHE is entitled to the best spot on the bed...and since she believes it's her job to decide who else gets to BE on the bed... she will sit in the spot that is closest to the stairs...thereby preventing both Chester and Olive from coming up. After all, by sitting right there, as she is below, they would have to nudge her aside or try and leap to the edge, and scramble up. (something both dogs are reluctant to do...)
I am quite certain Emily is aware of this. How do I know? Well, we used to keep the steps on the right side of the bed... and Emily would lay over there. We moved the steps, albeit to prevent Emily from lording it over Chester and Olive...and ... Emily merely moved where she sits. She knew, immediately, that moving the steps meant she had to move her perch, also.
And people say dogs don't think!
(just look at her face... what does it tell you???)