Full Idea
It is plausible that you and I can have perceptual experiences with the same phenomenology of two trees at different distances from us (perhaps at different times). ..So our perceptual experiences cannot contain you or me in the content of representation.
Gist of Idea
If two people can have phenomenally identical experiences, they can't involve the self
Source
Berit Brogaard (Perceptual Content and Monadic Truth [2009], p.223), quoted by Cappelen,H/Dever,Josh - The Inessential Indexical 08.2
Book Reference
Cappelen,H/Dever,J: 'The Inessential Indexical' [OUP 2013], p.147
A Reaction
If you accept the example, which seems reasonable, then that pretty conclusively shows that perception is not inherently indexical.