I am quite sure every person who has used a computer has made this particular mistake: The task you are undertaking is moving along too slowly, or not at all. What do we all do? We start clicking, moving the cursor around (if it is willing to move, that is) and click on boxes, words, icons, whatever we find. We make the mistaken assumption that we can hurry the process along. And then we often find ourselves completely "frozen" and have to shut things down and start over.
The same thing happens when we are interacting with people who struggle to communicate. Since they have something different about their neurological wiring, and since we really do not understand just what that might be, we make a serious error every single time we repeat a verbal instruction.
Instead may I suggest the following: Say it once, let them start to process what has been said, and then WAIT! Don't repeat. I repeat: DON'T REPEAT. If they don't respond in some way in a minute or so, switch to another sensory system. Touch them lightly, show them a picture, pantomime what you are asking of them, point, or put your comment in writing. Anything is worth a try - but if we keep repeating spoken words, we are essentially restarting the process over again from the beginning, wasting valuable time and energy, and risking a meltdown, or at least getting stuck or frozen and unable to act.
It's a grandma thing that works with kids who aren't on the autism spectrum as well. We had our two youngest granddaughter with us recently and were excitedly getting ready to go to the zoo. Correction: Grandpa and Grandma were getting ready, while the girls (ages six and almost three) were causing multiple distractions and delays. As I tried to finish packing a somewhat healthy lunch for all of us, I found myself talking to the girls, making suggestions that were clearly falling on deaf ears. I got a little louder and they got sillier. We were NOT moving forward, and I was getting frustrated.
Then I remembered a lesson learned long ago, but forgotten in the moment. I stopped talking, found a piece of paper and started making a list. The six-year-old is a new reader and so very proud of her ability. She was immediately interested in what I was writing (and I suppose also wondering why I had suddenly gone quiet). Carefully she sounded out the words on the list - jackets, shoes, bathroom, umbrella, lunch . . . And right away (being a very smart granddaughter, of course!) she caught on. She still had to irritate her younger sister, but in between the teasing and chasing, she started doing what she could to help us get ready to leave.
I had a wonderful paraprofessional working with me years ago. She accompanied one of our students to his regular classes, helping him with academics as needed, but mostly helping him overcome his many anxieties. Among many other worries, he lived in almost constant fear that there would be an announcement on the public address system - even though such announcements were extremely rare. She discovered that she could draw simple stick figure pictures to help him understand that the voice of "the MAN" was actually coming from our very kind principal. Through a combination of pictures and words along with the universal NO sign (cross-through) she could put him at ease so that he could make it through most of his classes. They visited the office regularly and involved the principal in the drawing/writing adventure.
With younger children, pictures may be most effective, but please do include the printed word as well. While we really don't know precisely how or when kids learn to read, I am totally convinced that the human brain is programmed to find the patterns, unlock the mystery and learn to make sense of written language. All kids need regular exposure to the printed word, along with picture and contextual clues. If we provide them with enough of this, they WILL learn to read - all of them!
If you must talk, talk quietly. If they don't seem to be listening, try talking even more quietly. Or stop talking entirely and switch to paper and pencil to get your message across. Repeating things orally or getting louder are all too often counter-productive and almost always lead to frustration.
Has this - or some other suggestion - worked for you? Do let us know!