Mathematical expressions in TeX files are displayed in a human-readable way

Question

When I type some mathematical expressions in Tex files using Vim, e.g. a_{2} = a_{1} + a_{0}, it is displayed in a human readable way like a2 = a1 + a0. (Actually the numbers are of a smaller font, but I don't know how to format mathematical expressions in Vi and Vim beta.) What I would like to know is what plugin is causing this effect. I just want to disable this feature since it's really annoying when moving cursor because it looks as if each of the numbers is consisted of one character but actually I have to type arrow keys several times to move from the number to the neighboring characters since the numbers correspond to something like _{2}.

I use Neobundle for managing plugins and I use the following plugins,

NeoBundle 'Shougo/neocomplete'
NeoBundle 'Shougo/neosnippet'
NeoBundle 'Shougo/neosnippet-snippets'
NeoBundle 'tpope/vim-fugitive'
NeoBundle 'ctrlpvim/ctrlp.vim'
NeoBundle 'flazz/vim-colorschemes'
NeoBundle 'Shougo/unite.vim'
NeoBundle 'thinca/vim-quickrun'
NeoBundle 'davidoc/taskpaper.vim'
NeoBundle 'itchyny/lightline.vim'
NeoBundle 'altercation/vim-colors-solarized'
NeoBundle 'git://git.wincent.com/command-t.git'
NeoBundle 'vim-latex/vim-latex'
NeoBundle 'surround.vim'
NeoBundle 'mattn/emmet-vim'
NeoBundle 'kchmck/vim-coffee-script'
NeoBundle 'vim-scripts/sudo.vim'
NeoBundle 'Shougo/neomru.vim'
NeoBundle 'tomtom/tcomment_vim'
NeoBundle 'vim-scripts/AnsiEsc.vim'
NeoBundle 'hallison/vim-markdown'
NeoBundle 'elzr/vim-json'
NeoBundle 'xolox/vim-session'
NeoBundle 'xolox/vim-misc'
NeoBundle 'tmhedberg/SimpylFold'
NeoBundle 'vim-ruby/vim-ruby'

I thought vim-latex has something to do with this but it turned out that it doesn't.

Answer 1

This functionality comes from the internal LaTeX plugin. See :h tex-conceal and :h g:tex_conceal. You can turn it off either by setting conceallevel=0 or by letting g:tex_conceal=''. To be more precise, you can use either of the following lines in your vimrc file:

let g:tex_conceal = ''
set conceallevel = 0

I propose that you read :h conceallevel before you set it to 0, since this will have an effect also for other file types.