Simulating the Acquisition of Verb Inflection in Typically Developing Children and Children With Developmental Language Disorder in English and Spanish

Children with developmental language disorder (DLD) have significant deficits in language ability that cannot be attributed to neurological damage, hearing impairment, or intellectual disability. The symptoms displayed by children with DLD differ across languages. In English, DLD is often marked by severe difficulties acquiring verb inflection. Such difficulties are less apparent in languages with rich verb morphology like Spanish and Italian. Here we show how these differential profiles can be understood in terms of an interaction between properties of the input language, and the child's ability to learn predictive relations between linguistic elements that are separated within a sentence. We apply a simple associative learning model to sequential English and Spanish stimuli and show how the model's ability to associate cues occurring earlier in time with later outcomes affects the acquisition of verb inflection in English more than in Spanish. We relate this to the high frequency of the English bare form (which acts as a default) and the English process of question formation, which means that (unlike in Spanish) bare forms frequently occur in third-person singular contexts. Finally, we hypothesize that the pro-drop nature of Spanish makes it easier to associate person and number cues with the verb inflection than in English. Since the factors that conspire to make English verb inflection particularly challenging for learners with weak sequential learning abilities are much reduced or absent in Spanish, this provides an explanation for why learning Spanish verb inflection is relatively unaffected in children with DLD.

Children's Production of Subject-Verb Agreement in Hebrew When Gender and Context are Ambiguous

Third and 5th grade Hebrew-speaking children performed two sentence completion tasks, one requiring the assignment of male, female, or gender-ambiguous names and the inflection of verbs for male-stereotyped, female-stereotyped, and gender-neutral activities, and the other task, of inflecting verbs for male- and female-stereotyped activities performed by children with gender-ambiguous names. The question of concern was whether when faced with the need to inflect verbs to match the conceptual gender of the sentence subject, the gender-stereotyped nature of the activities in question and children's own gender would play a role in resolving the dilemma created by gender-ambiguous names and contexts. In both parts of the study, we found that (1) children's own gender played a role in determining the pattern of verb inflection, and (2) children used their semantic knowledge regarding the gender-stereotyped nature of activities to inflect verbs so as to create subject-verb agreement. Hence, subject-verb agreement in children draws on both their grammatical and semantic knowledge.

Production and Comprehension of Time Reference in Korean Nonfluent Aphasia

Objectives

Individuals with nonfluent agrammatic aphasia show impaired production and comprehension of time reference via verbal morphology. However, cross-linguistic findings to date suggest inconsistent evidence as to whether tense processing in general is impaired or time reference to the past is selectively difficult in this population. This study examined production and comprehension of time reference via verb morphology in Korean-speaking individuals with nonfluent aphasia.

Methods

A group of 9 healthy controls and 8 individuals with nonfluent aphasia (5 for the production task) participated in the study. Sentence priming production and auditory sentence to picture matching tasks were used, parallel with the previous cross-linguistic experiments in English, Chinese, Turkish, and others.

Results

The participants with nonfluent aphasia showed different patterns of impairment in production and comprehension. In production, they were impaired in all time references with errors being dominated by substitution of incorrect time references and other morpho-phonologically well-formed errors, indicating a largely intact morphological affixation process. In comprehension, they showed selective impairment of the past, consistent with the cross-linguistic evidence from English, Chinese, Turkish, and others.

Conclusion

The findings suggest that interpretation of past time reference poses particular difficulty in nonfluent aphasia irrespective of typological characteristics of languages; however, in production, language-specific morpho-semantic functions of verbal morphology may play a significant role in selective breakdowns of time reference.