By Christina Farr SAN FRANCISCO (Reuters) – Advocates for the blind are debating whether to use a carrot or a stick to persuade one of their oldest allies, Apple Inc, to close an emerging digital divide in mobile technology. Few disabled want to risk alienating Apple, considered a friend, by fighting it. Captions on videos and special hearing aids bring hearing impaired into the digital fold. I get nervous every time I hit the update button. LinkedIn has hired an accessibility chief, Jennison Asuncion, who himself is blind, and says it is working to improve the app.