Christina Bergmann

Preschoolers’ comprehension of pronouns and reflexives: The impact of the task

Pronouns seem to be acquired in an asymmetrical way, where children confuse the meaning of pronouns with reflexives up to the age of six, but not vice versa. Childrens production of the same referential expressions is appropriate at the age of four. However, response-based tasks, the usual means to investigate child language comprehension, are very demanding given childrens limited cognitive resources. Therefore, they might affect performance. To assess the impact of the task, we investigated learners of Dutch (three- and four-year-olds) using both eye-tracking, a non-demanding on-line method, and a typical response-based task. Eye-tracking results show an emerging ability to correctly comprehend pronouns at the age of four. A response-based task fails to indicate this ability across age groups, replicating results of earlier studies. Additionally, biases seem to influence the outcome of the response-based task. These results add new evidence to the ongoing debate of the asymmetrical acquisition of pronouns and reflexives and suggest that there is less of an asymmetry than previously assumed.

Promoting replicability in developmental research through meta-analyses: Insights from language acquisition research

Previous work suggests that key factors for replicability, a necessary feature for theory building, include statistical power and appropriate research planning. These factors are examined by analyzing a collection of 12 standardized meta‐analyses on language development between birth and 5 years. With a median effect size of Cohens d = .45 and typical sample size of 18 participants, most research is underpowered (range = 6%–99%; median = 44%); and calculating power based on seminal publications is not a suitable strategy. Method choice can be improved, as shown in analyses on exclusion rates and effect size as a function of method. The article ends with a discussion on how to increase replicability in both language acquisition studies specifically and developmental research more generally.

A model of the headturn preference procedure: Linking cognitive processes to overt behaviour

The study of first language acquisition still strongly relies on behavioural methods to measure underlying linguistic abilities. In the present paper, we closely examine and model one such method, the headturn preference procedure (HPP), which is widely used to measure infant speech segmentation and word recognition abilities Our model takes real speech as input, and only uses basic sensory processing and cognitive capabilities to simulate observable behaviour.We show that the familiarity effect found in many HPP experiments can be simulated without using the phonetic and phonological skills necessary for segmenting test sentences into words. The explicit modelling of the process that converts the result of the cognitive processing of the test sentences into observable behaviour uncovered two issues that can lead to null-results in HPP studies. Our simulations show that caution is needed in making inferences about underlying language skills from behaviour in HPP experiments. The simulations also generated questions that must be addressed in future HPP studies.

Measuring word learning performance in computational models and infants

In the present paper we investigate the effect of categorising raw behavioural data or computational model responses. In addition, the effect of averaging over stimuli from potentially different populations is assessed. To this end, we replicate studies on word learning and generalisation abilities using the ACORNS models. Our results show that discrete categories may obscure interesting phenomena in the continuous responses. For example, the finding that learning in the model saturates very early at a uniform high recognition accuracy only holds for categorical representations. Additionally, a large difference in the accuracy for individual words is obscured by averaging over all stimuli. Because different words behaved differently for different speakers, we could not identify a phonetic basis for the differences. Implications and new predictions for infant behaviour are discussed.

Investigating word learning processes in an artificial agent

Researchers in human language processing and acquisition are making an increasing use of computational models. Computer simulations provide a valuable platform to reproduce hypothesised learning mechanisms that are otherwise very difficult, if not impossible, to verify on human subjects. However, computational models come with problems and risks. It is difficult to (automatically) extract essential information about the developing internal representations from a set of simulation runs, and often researchers limit themselves to analysing learning curves based on empirical recognition accuracy through time. The associated risk is to erroneously deem a specific learning behaviour as generalisable to human learners, while it could also be a mere consequence (artifact) of the implementation of the artificial learner or of the input coding scheme. In this paper a set of simulation runs taken from the ACORNS project is investigated. First a look ‘inside the box’ of the learner is provided by employing novel quantitative methods for analysing changing structures in large data sets. Then, the obtained findings are discussed in the perspective of their ecological validity in the field of child language acquisition.

Modelling the Noise-Robustness of Infants’ Word Representations: The Impact of Previous Experience

During language acquisition, infants frequently encounter ambient noise. We present a computational model to address whether specific acoustic processing abilities are necessary to detect known words in moderate noise—an ability attested experimentally in infants. The model implements a general purpose speech encoding and word detection procedure. Importantly, the model contains no dedicated processes for removing or cancelling out ambient noise, and it can replicate the patterns of results obtained in several infant experiments. In addition to noise, we also addressed the role of previous experience with particular target words: does the frequency of a word matter, and does it play a role whether that word has been spoken by one or multiple speakers? The simulation results show that both factors affect noise robustness. We also investigated how robust word detection is to changes in speaker identity by comparing words spoken by known versus unknown speakers during the simulated test. This factor interacted with both noise level and past experience, showing that an increase in exposure is only helpful when a familiar speaker provides the test material. Added variability proved helpful only when encountering an unknown speaker. Finally, we addressed whether infants need to recognise specific words, or whether a more parsimonious explanation of infant behaviour, which we refer to as matching, is sufficient. Recognition involves a focus of attention on a specific target word, while matching only requires finding the best correspondence of acoustic input to a known pattern in the memory. Attending to a specific target word proves to be more noise robust, but a general word matching procedure can be sufficient to simulate experimental data stemming from young infants. A change from acoustic matching to targeted recognition provides an explanation of the improvements observed in infants around their first birthday. In summary, we present a computational model incorporating only the processes infants might employ when hearing words in noise. Our findings show that a parsimonious interpretation of behaviour is sufficient and we offer a formal account of emerging abilities.

Grammatical Gender Influences Dutch 5-year-olds' Pronoun Interpretation in a Pointing Task

Alternative account: Task effects and differences in processing cost Experiments require more than just comprehension Interpretation: Who is meant by “her” or “herself ”? Reflexive “herself ” → Referent within the same phrase Low impact on memory / attention Pronoun “her” → Referent outside the phrase High impact on memory / attention Additional Task: • Store interpretation • Compare spoken sentence to visual referents • Select appropriate response (pointing, saying “yes” / “no”) • Execute response Grammatical Gender