I recently installed a programming package, "Haskell mode," and apparently I changed how "initial parenthesis highlighting" works. I'm used to a quick black/white box superimposed on the initial parenthesis. Now there is a solid colored box that lingers for a while. How do I change this back to the default behavior?
The original behaviour you describe sounds like
blink-matching-paren is a variable defined in
Non-nil means show matching open-paren when close-paren is inserted. If t, highlight the paren. If `jump', move cursor to its position.
The new behaviour you are seeing sounds like
show-paren-mode. From the help for that function:
Show Paren mode is a global minor mode. When enabled, any matching parenthesis is highlighted in
show-paren-delayseconds of Emacs idle time.
As @nitishch commented, you can turn off
(show-paren-mode -1). You can customize the behaviour of
M-x customize-variable blink-matching-paren. You can customize
M-x customize-group paren-showing - this allows you to set the delay before showing parens, and the faces (fonts) used to highlight them.