This is due to something called Metathesis.
From Wikipedia on Metathesis
Metathesis...is the transposition of sounds or syllables in a word or of words in a sentence. Most commonly, it refers to the interchange of two or more contiguous sounds, known as adjacent metathesis or local metathesis.
Metathesis may also involve interchanging non-contiguous sounds...
Metathesis is responsible for some common speech errors, such as children acquiring spaghetti as pasketti. The pronunciation /ˈæsk/ for ask, now considered standard, descends from a northern England version of the verb that in most midland and southern texts through the 1500s was spelled with x or cs, showing pronunciation as /ˈæks/. Chaucer, Caxton, and the Coverdale Bible use ax; Shakespeare and the King James Bible have ask. The word "ask" derives from Proto-Germanic *aiskōną.
Some other frequent English pronunciations that display metathesis are:
- comfortable > comfterble /ˈkʌmftərbəl/
- nuclear > nucular /ˈnjuːkjʊlər/ (re-analysed as nuke + -cular suffix in molecular,
- prescription > perscription /pərˈskrɪpʃən/
- interduce /ɪntərˈd(j)uːs/
- asterisk > asterix /ˈæstərɪks/
- cavalry > calvary /ˈkælvəri/
- foliage > foilage /ˈfɔɪlɪdʒ/
- pretty > purty /ˈpɜːrti/
It is likely that English-speaking children mix up this word more than Norwegian children because of how first language acquisition affects our ability to pronounce words. In English, here are the words that an English-speaking 2 year old should be able to say. As you can see, the most simple words have consonant-vowel-consonant (CVC), CVCC, or CVVC syllables (dad, mom, ball, door, milk, bad, good). English speaking children, therefore, have an easier time with these syllables than CCV syllables.
Common examples of children altering CCV syllables:
- "spa" > "pas" in spagetti
- "brain" > "bain"
- "specific" > "pacific"
- "library" > "libery"