"Who did you see [a picture of ___]?" (The phrase is the object).
Some researchers suggest the problem isn't grammar, but . Islands
Extracting from a subject might simply be too mentally taxing for the brain to process in real-time. Exceptions and "Parasitic" Gaps "Who did you see [a picture of ___]
Many generative grammarians argue that islands are a result of the of human language. Islands