The odd thing with ds1 is that he scored high average for working memory on his WISC IV test (his lowest score was for processing speed). He actually scored unusually high on the reverse digit span test (scored at adult level), which totally confused the EP at the time and meant she had to consult on the results.
He has an incredible memory for facts and things that happened a long time ago. He can sit in a class and 'listen' whilst reading a paperback and still be able to recount all the main facts of the lesson, but if you give him an instruction, he is unable to plan, organise and co-ordinate his thoughts and actions well enough to do it. For me the executive function thing makes more sense for him.
If I quote the first paper I linked to:
"If we break down the skills or functions into sub functions, we might say that executive functions tap into the following abilities or skills: goal, plan, sequence, prioritize, organize, initiate, inhibit, pace, shift, self-monitor, emotional control and completing."
... and think of someone who can't do the things it lists, I have basically just described ds1.
I also find this:
"Executive functioning does not have one definition agreed on by researchers,
however, it is generally considered to describe the set of skills an executive would need to stay on top of his or her job; planning, organizing, prioritizing, multi-tasking.
Executive dysfunction may make it difficult to maintain a topic in a conversation as the student with ASD has difficulty maintaining a sense of order in his spoken messages often producing tangential responses, he or she may also have difficulty with the organization of written expression or independently planning to complete class assignments."
Sums him up really well, in relation to schoolwork and conversational skills. He can talk your ears off when it's a list of facts or an obsessional topic he's learned by rote, but he can't relate an event that's happened in the right order and he really struggles with the organisational planning and structuring that's required to complete schoolwork or say, going upstairs and getting himself properly dressed and ready to go out.
Imo, working memory issues will look the same/cause similar problems, but as you can see from ds's results it's not always the case, so simply working on working memory skills won't necessarily improve things. In the absence of testing such as the WISC or Ravens tests, it's definitely worth trying some WM exercises in the first instance though.
I have a feeling ds did so well on the digit span because he loves numbers and is good at retaining facts, particularly when they relate to patterns or series. If the test had been about recalling the right actions to do something as simple as make a cup of tea (fill kettle, close lid, plug in, switch on, etc) I have no doubt he would have scored extremely low. So, I'm not 100% convinced that the WISC WM tests are a good indicator of WM skills, but that's purely based on my/our own experience and I could be way off the mark.