What is the phenomena of using words with opposite meanings accidentally called?

[Vicarious Reality]

I know it is not Spoonerism, that is when you take one part of a word and exchange it with the other to form new words

I say left when i mean right often, and similar things like dark & light, warm & cold

I could not google this at all, i feel IT impotent

 

[Starnerf]

Sounds like a malapropism but swapping words with related meanings instead of words that sound similar.

I think that's a form of dyslexia, actually, but I'm not a doctor so don't quote me on that.

 

[SckizoBoy]

snip

Eh... the only thing I can think of is antonymic substitution... just a specific form of substitution when the speaker means one thing and says another, though while grammatically, it still makes sense, it confuses the speaker's lexicon. Synonymy is one, but context makes it sound weird, while other cases it takes rhyming words, so antonymy seems the closest... *shrugs* dunno if that helps... -.-

 

[Asita]

Proper diction? No...wait...wrong phrase...Seems just like a specific kind of malapropism or catachresis to me. Not sure if there's a term specifically relating to the mistaken use of an antonym though :/

 

[Johnny Novgorod]

Schizophasia? Also known as "word salad".

 

[Vicarious Reality]

Interesting
So i take it this is not a common problem?
The second result, and probably the first correct one when i google ''antonymic substitution'' is this very thread
This seems like the place to be: http://en.wikipedia.org/wiki/Opposite_(semantics)