You would know because she would make errors. Kids don’t stop talking because they don’t know the right word. You know that irregular past tense is hard(er) for kids to learn because they say things like ‘runned’ and ‘eated’. In some cases it might be a circumlocution rather than an error (‘I’m the big one’ in place of ‘I’m the biggest’), but it’s not hard to know what a kid is having trouble learning if you are paying attention.
I haven’t noticed her making errors that obviously relate to polysemy like that of “post”. But I’m not sure what such errors would look like; my best guess is that if such things are a problem their main impact is probably just extra cognitive load, hence slower learning generally.
Slower processing evidenced by slower response or stated confusion would be the most likely result. Polysemy is actually good for helping kids practice using context cues, so it is arguable that even if she was making errors, it would still be a good thing from an educational standpoint.
It is worth noting that when linguists complain about how bad English is, they do not complain about polysemy, but about deep orthography and some nasty grammatical rules. It is also worth noting that English is pretty much average as far as polysemy goes, at least in European languages—although this may depend on whether you consider idiomatic phrasal verbs to be polysemies of the composite words.
Sidenote:
You would know because she would make errors. Kids don’t stop talking because they don’t know the right word. You know that irregular past tense is hard(er) for kids to learn because they say things like ‘runned’ and ‘eated’. In some cases it might be a circumlocution rather than an error (‘I’m the big one’ in place of ‘I’m the biggest’), but it’s not hard to know what a kid is having trouble learning if you are paying attention.
I haven’t noticed her making errors that obviously relate to polysemy like that of “post”. But I’m not sure what such errors would look like; my best guess is that if such things are a problem their main impact is probably just extra cognitive load, hence slower learning generally.
Slower processing evidenced by slower response or stated confusion would be the most likely result. Polysemy is actually good for helping kids practice using context cues, so it is arguable that even if she was making errors, it would still be a good thing from an educational standpoint.
It is worth noting that when linguists complain about how bad English is, they do not complain about polysemy, but about deep orthography and some nasty grammatical rules. It is also worth noting that English is pretty much average as far as polysemy goes, at least in European languages—although this may depend on whether you consider idiomatic phrasal verbs to be polysemies of the composite words.