The Extreme Close Up (ECU) is where the camera is focused tightly on a specific body part (Eyes, Mouth, Hand etc). The ECU is used to bring the audiences attention to this part, showing that is represents something that is very important to know or see. This is used sparingly, but is used when the film-maker wants to make a big point about a small action.
Because the camera is extremely close, it can be used to unsettle the audience, or to make a subtle action that only the audience knows about (and possibly not other characters in the scene). Horror uses this often to show a characters eyes scanning, looking for danger, which amplifies the fear the characters are experiencing, and doesn't give the audience any new information to set their fears at ease.
An ECU of the original cookie jar - foreshadows the importance this plays in the story.
The new cookie jar, the ECU amplifies its sinister look, as if it is peering deep into Bree's soul.
The strange angle to this ECU unsettles the audience, and builds tension in anticipation of something happening to Bree.
This ECU of Kookie actually inside the TV show that Bree watches, is the first hint that Kookie is more than a cookie jar.
The ECU of these photos gives us a sense of what is normal - happy times with mum - but also foreshadows their use later, to disrupt 'normal', and show happiness as a past memory.
ECU used later in the film, shows how disturbed Bree is, and how she is now obsessed with Kookie.