I'm not sure if this is what you are referring to but my DH cannot say a word if he pictures the person or object in his head. He will often substitute odd but not totally unrelated words or use sentences without nouns as a work around. It can make a conversation very difficult for the other person. For example he might say "Can you grab that for me? That! Behind you! That... the thing with the papers inside it. You know for your nose..." "Oh you mean the box of tissues?" "Yes! That's what I was trying to say."
When my 2E daughter was first identified and I was reading everything I could get my hands on to try to get a handle on all her LD issues I read a description of a specific type of dyslexia that fit what DH does. It described him perfectly. Unfortunately I can't remember the name (ironic I know...) or which of the dozens of books or articles I found it in. He did this at an early IEP meeting for my daughter and I referenced it appearing that he had that specific type of dyslexia and the very good, very experienced spec Ed teacher nodded her head in agreement.
DD can't remember names unless the person is very important to her (and may even substitute "mommy" and "daddy" when speaking to one of us) but generally is very good about nouns, great at verbs and beyond spectacular at using just the right adjective or adverbs. She was recently started on a new medication for her migraines and we were told a common side effect would be losing the ability to find the right word. Sorry I don't know why.
Hope this rambling may help.
