My cats Georgia (top) and Henry (middle) enjoy their new toy, a small fishbowl. Georgia puts her head inside while also kicking and grabbing at other toys, while Henry's more apt to just sit placidly with his head in the bowl, looking around. They stay there for long periods of time, Henry often for up to 45 minutes, his breath steaming up the glass.
I don't know why. And so, Houston, we have a problem:
Maybe they like the sonic environment it creates — a world where the only sound is their own breathing, like nursing with their mother. On the other hand, they don't purr or knead when they do this (for a change — they are avid nursers).
Maybe the glass distorts the room, making things look "weird" — and certainly, they like their world when it's defamiliarized. Georgia, who often seems a little bored, likes touring the apartment atop my shoulders. On the other hand, she uses the bowl for shorter periods than Henry and does less "looking" while she's there. Henry, who's less bored with his surroundings, enjoys the view more.
Therefore, my pet theory (sorry for the pun) is that they're pretending that they're astronauts (e.g., John Glenn, also shown above for easy comparison). I believe they imagine themselves to be in Outer Space. They must appreciate this, as I do, as a metaphor for their status as The Other, as representatives from outside of language and discourse, emissaries from a place beyond history and culture.