There was a benefit in reading out loud. As you learned to read you built the vocabulary and your minds ability to process the written language. Once you do that you graduate to the faster process of silent reading and minimal subvocalisation.
When it comes to visual images your mind has always been processing and making snap decisions about them. Talking out loud slows that down so that you can actually 'see it'
It's interesting. We want our minds speed and ability to process visual information for meaning to transfer reading, for faster non-conscious processing and understanding. And would like to transfer our reading comprehension (conscious understanding) to our visual ability. Talking seems to be a largely conscious process and so slows everything down.
Alex
