Acquisition of cumulative conditioning effects on words: Spanish-speaking children’s [subject pronoun + verb] usage

Child language acquisition research has provided ample evidence of lexical frequency effects. This corpus-based analysis introduces a novel frequency measure shown to significantly constrain adult language variation, but heretofore unexplored in child language acquisition research. Among adults, frequent occurrence of a form in a particular discourse context that conditions usage accumulates in memory over time and shapes the lexical representation of that form. This study contributes to the body of research on frequency effects in child language acquisition by testing whether such cumulative conditioning effects are also found among children, and, if so, at what age such effects appear. Specifically, the study investigates the influence of a distributional frequency measure (each verb form’s likelihood of use in a switch vs same-reference discourse context) on variable subject personal pronoun (SPP) expression ( N = 2227) in Spanish (e.g. yo voy ~ voy, both meaning ‘I go’) in the speech of 65 monolingual children in two age cohorts. Results reveal sensitivity to the contextual conditioning of discourse continuity (switch reference) among both the younger (6- and 7-year-olds) and older (8- and 9-year-olds) children in support of previous research. In addition, each verb’s likelihood of use in a switch-reference context significantly predicted the SPP use among the older children, but not the younger ones, suggesting that the cumulative effect of a probabilistic pattern takes time to emerge during childhood. The lexically specific accumulation in memory of contextual conditioning effects supports exemplar models of child language acquisition: each instance of use in discourse contributes to the lexical representation of that form and, over time, plays a role in the creation of morphosyntactic patterns during language development.

Theta- and gamma-band oscillatory uncoupling in the macaque hippocampus

Nested hippocampal oscillations in the rodent gives rise to temporal coding that may underlie learning, memory, and decision making. Theta/gamma coupling in rodent CA1 occurs during exploration and sharp-wave ripples during quiescence. Whether these oscillatory regimes extend to primates is less clear. We therefore sought to identify correspondences in frequency bands, nesting, and behavioral coupling taken from macaque hippocampus. We found that, in contrast to the rodent, theta and gamma frequency bands in macaque CA1 were segregated by behavioral states. Beta/gamma (15-70Hz) had greater power during visual search while theta (7-10 Hz) dominated during quiescence. Moreover, delta/theta (3-8 Hz) amplitude was strongest when beta2/slow gamma (20-35 Hz) amplitude was weakest, though the low frequencies coupled with higher, ripple frequencies (60-150 Hz). The distribution of spike-field coherence revealed three peaks matching the 3-10 Hz, 20-30 Hz and 60-150 Hz bands; however, the low frequency effects were primarily due to sharp-wave ripples. Accordingly, no intrinsic theta spiking rhythmicity was apparent. These results support a role for beta2/slow gamma modulation in CA1 during active exploration in the primate that is decoupled from theta oscillations. These findings diverge from the rodent oscillatory canon and call for a shift in focus and frequency when considering the primate hippocampus.

Modeling Morphology With Linear Discriminative Learning: Considerations and Design Choices

This study addresses a series of methodological questions that arise when modeling inflectional morphology with Linear Discriminative Learning. Taking the semi-productive German noun system as example, we illustrate how decisions made about the representation of form and meaning influence model performance. We clarify that for modeling frequency effects in learning, it is essential to make use of incremental learning rather than the end-state of learning. We also discuss how the model can be set up to approximate the learning of inflected words in context. In addition, we illustrate how in this approach the wug task can be modeled. The model provides an excellent memory for known words, but appropriately shows more limited performance for unseen data, in line with the semi-productivity of German noun inflection and generalization performance of native German speakers.

Reading Development, Word Length and Frequency Effects: An Eye-Tracking Study with Slow and Fast Readers

Research on reading development attempts to explain differences in the reading patterns of adults and children. Previous studies, which typically analyzed word length and frequency effects in developing readers, often focused on dyslexic or dysfluent readers. Similar to previous studies, we investigated the effects of word length and word frequency on the eye movements of children and added several novel aspects: We tested 66 typically developing German-speaking children. Children’s oral reading fluency was used as measure of reading ability. Only fast readers (n = 34, mean age 10.9 ± 0.9 years) and slow readers (n = 32, 11.2 ± 0.9 years) participated in an eye-tracking experiment and silently read an age-appropriate original narrative text from a children’s book. The analysis of silent reading of the entire text confirmed the earlier group classification. To analyze word length and frequency, we selected 40 nouns as target words in the text. We found significant effects of word length and word frequency for all children in the expected direction. For fast readers, we detected significant interactions of word length and frequency in first fixation duration, gaze duration, and total reading time. These revealed a frequency effect for long, but not short words. This suggests lexical whole-word processing with a fast activation of the word’s lexical entry for shorter words and an application of the nonlexical route of the dual route cascaded model (DRC) with a slower lexical access to whole word forms for long words. Slow readers demonstrated a strong sensitivity to word length, indicating a slower or delayed lexical access to orthographic word forms. Additionally, they exhibited weaker word frequency effects. These findings suggest a developmental view of reading in typically developing children in accordance with the DRC, with nonlexical serial decoding as the seemingly prominent reading strategy of slow readers and lexical whole-word recognition as the prominent reading strategy of fast readers.