Acquiring English past tense

My grandson (aged 3 years 9 months) has recently started producing the past tense in a surprising way. I first noticed it with the form liked. He is now pronouncing this as likèd [laɪkɛd] , rather than [laɪkt]. I soon discovered he was using this form consistently not only in all weak verbs but even in some strong verb. For example instead of saying brought, he is saying bringed, which he pronounced as bringèd. The only strong verbs I noticed him using the correct form for were did and went. Because this feature of his speech is now so pervasive, I expect I would have noticed it before if it was present, so I’m sure he wasn’t doing this until the last couple of weeks.

While children are acquiring language, they often overgeneralise. For example, it would not be surprising to hear a young child say runned instead of ran. But I was surprised to hear my grandson consistently using the form ending in [-ɛd] for all weak forms.

Why did this surprise me?

To understand why this surprised me, it is worth looking at the various forms (allomorphs) of the suffix added in creating the past tense of English weak verbs. The suffix is generally /-d/. For example, the past tense of beg is begged [pronounced bɛgd]. But this suffix is adjusted in two cases:

• the suffix surfaces as [-t], the unvoiced counterpart of [-d], if the vowel ends in an unvoiced consonant, for instance [-p] or [-k]. For example, the past tense of kick is kicked [kɪkt]
• a vowel [-ɪ-] is inserted before the suffix if the verb ends in the dental sounds [-t] or [-d]. For example, the past tense of wait is waited [weɪtɪd].

Why did he change?

I wouldn’t have been surprised if he had generalised a form used for a large class of weak verbs. But I am surprised that he has generalised a form [-ɪd] used for only a narrow class of verbs to apply it to all weak verbs. For this narrow class, the phonetic motivation for this particular form is easy to understand: the inserted vowel [-ɪ-] makes it easier to produce and detect the dental ending [-d] by separating it from a preceding dental consonant (-d or -t).

But if the dental ending is added after other consonants, English speakers have no trouble pronouncing and detecting the sequence that results. So the sound system of English does not require a vowel to be inserted in those cases. And it is a mystery why he now feels the need to insert the vowel in all cases. Also, although this ending is typically written -ed, even when no vowel is pronounced, the written form can’t be affecting him because he can’t read yet.

Why change now?

It’s interesting that he has suddenly started producing the past tense this way now. He has been using the past tense confidently for perhaps 18 months or 2 years. Clearly his mind is restructuring (no doubt unconsciously) its understanding of the English systems of morphology (word forms), phonology (sounds) and phonotactics (sound sequences). It will be interesting to see how this develops over the next few months.