Insights into Early Word Comprehension: Tracking the Neural Representations of Word Semantics in Infants.

Infants start developing rudimentary language skills and can start understanding simple words well before their first birthday. This development has also been shown primarily using Event Related Potential (ERP) techniques to find evidence of word comprehension in the infant brain. While these works validate the presence of semantic representations of words (word meaning) in infants, they do not tell us about the mental processes involved in the manifestation of these semantic representations or the content of the representations. To this end, we use a decoding approach where we employ machine learning techniques on Electroencephalography (EEG) data to predict the semantic representations of words found in the brain activity of infants. We perform multiple analyses to explore word semantic representations in two groups of infants (9-month-old and 12-month-old). Our analyses show significantly above chance decodability of overall word semantics, word animacy, and word phonetics. As we analyze brain activity, we observe that participants in both age groups show signs of word comprehension immediately after word onset, marked by our model's significantly above chance word prediction accuracy. We also observed strong neural representations of word phonetics in the brain data for both age groups, some likely correlated to word decoding accuracy and others not. Lastly, we discover that the neural representations of word semantics are similar in both infant age groups. Our results on word semantics, phonetics, and animacy decodability, give us insights into the evolution of neural representation of word meaning in infants.

The Wernicke conundrum revisited: evidence from connectome-based lesion-symptom mapping in post-stroke aphasia

The classical assumption that word and sentence comprehension deficits in stroke aphasia follow from damage to Wernicke's area has been questioned following discrepant results in primary progressive aphasia. We tested the hypothesis of Mesulam et al. (2015; 2019) that word and sentence comprehension deficits in stroke aphasia result from 'double disconnection' due to white matter damage: word comprehension deficits resulting from disconnection of the anterior temporal lobe and sentence comprehension deficits resulting from disconnection of the frontal lobe. We performed lesion-deficit correlations, including connectome-based lesion-symptom mapping, in four large, partially overlapping groups of English-speaking chronic left hemisphere stroke survivors. After removing variance due to object recognition and associative semantic processing, the same middle and posterior temporal lobe regions were implicated both in word comprehension deficits (N = 180) and complex noncanonical sentence comprehension deficits (N = 131). Repetition deficits (N = 218) were associated with damage to the posterior temporal lobe and superior longitudinal fasciculus, and agrammatic production (N = 92) was associated with damage to the posterior middle frontal gyrus. Connectome lesion-symptom mapping revealed similar temporal-occipital white matter disconnections for impaired word and noncanonical sentence comprehension, including the temporal pole. We found additional significant temporal-parietal disconnections for noncanonical sentence comprehension deficits, which may indicate a role for phonological working memory in processing complex syntax, but no significant frontal-temporal or frontal-parietal disconnections. By contrast, repetition deficits were associated with a very large set of significant disconnections, including frontal-temporal disconnections, and agrammatic production was associated primarily with significant disconnections within the frontal lobe. Our results largely agree with the classical notion that damage to Wernicke's area causes both word and sentence comprehension deficits in stroke-based aphasia, suggest a supporting role for temporal pole in both word and sentence comprehension, and speak against the hypothesis that sentence comprehension deficits in Wernicke's aphasia result from frontal-temporal or frontal-parietal disconnections.

EFFICIENCY OF HEARING AID FOR HEARING LOSS CHILDREN UNDER 3 YEARS OLD AT NATIONAL CHILDREN HOSPITAL IN 2018-2019

A self-controlled intervention study was conducted on a group of hearing loss children who wear hearing aids at the National Children Hospital January 2018 to August 2019. The purpose of the study is to evaluate the effectiveness of the hearing aid on these children. Data were taken by questionnaires and analyzed using Stata software. The results showed that the average improvement of the hearing threshold in 71 hearing loss ears after wearing hearing aids was 49.2 ± 9.5dB. In which improvement at frequency 500 Hz is 47.5 ± 10.9dB; frequency 1000 Hz is 49.9 ± 10.5dB; frequency 2000 Hz is 50.2 ± 10.1dB; frequency 4000 Hz is 47.9 ± 10.2dB. The SII index improve 38.5 ± 27.4%. The Maximum word comprehension improve 60.9 ± 38.5%. The Maximum sentence comprehension improve 73 ± 34.2.

The effect of phonological complexity on the order in which words are acquired in early childhood

During the second year of life, children acquire words and expand their receptive and expressive vocabularies at a rapid pace. At this age, toddlers’ phonological abilities are also developing rapidly. The current study investigated the effect of phonological complexity of words on the order in which they are acquired, receptively and expressively. Data were collected from Hebrew-speaking parents of 881 typically developing toddlers: 417 girls and 464 boys, aged 1;0 to 2;0 years old. Parents reported on their child’s receptive and expressive vocabularies by completing a computerized version of the Hebrew adaptation of the MacArthur-Bates Communicative Development Inventories. Phonological complexity scores of the target words were calculated using the Phonological Mean Length of Utterances measure. The proportion of children who were reported to understand and produce each word at each age was calculated. Results showed that phonological complexity affected the acquisition of word comprehension and word production. Words that are less phonologically complex were acquired earlier, representing a process of subconscious selection of words that are easier to produce.

Two-year-olds’ eye movements reflect confidence in their understanding of words

We study the fundamental issue of whether children evaluate the reliability of their language interpretation, i.e., their confidence in understanding words. In two experiments, two-year- olds (n1 = 50; n2 = 60) saw two objects and heard one of them being named; both objects were then hidden behind screens and children were asked to look towards the named object, which was eventually revealed. When children knew the label used, they showed increased post-decision persistence after a correct compared to an incorrect anticipatory look, a marker of decision confidence in word comprehension (experiment 1). When interacting with an unreliable speaker, children showed accurate word comprehension, but reduced confidence in the accuracy of their own choice, indicating that children’s confidence estimates are influenced by social information (experiment 2). Thus, by 2 years, children can estimate their confidence during language comprehension, long before they can reflect upon and talk about their linguistic skills.

How Reliable is the Give-a-Number task?

The Give-a-Number task has become a gold standard of children’s number word comprehension and has been increasingly used to organize debate in developmental psychology. In this task, the experimenter asks children to give specific numbers of objects (e.g., 1 to 6), and based on their pattern of responses, children are classified into stages that can be readily related to other developmental milestones. The increasing popularity of Give-a-Number raises the question of how reliable it is, since the size of a correlation between two different tasks cannot reliably exceed the test- retest reliability of either measure taken individually. In Experiment 1, 2- to 4-year-old children were tested twice in a single session with Wynn’s (1992) version of the Give-a- Number task, which features a titrated design. In Experiment 2, we tested a second group of children with an alternative version that uses a larger number of trials in a non-titrated design. We found that in both cases the task was highly reliable in differentiating children who could accurately count from those who could not, but that reliability differed for specific numbers, and was more reliable for very small numbers (i.e., “one” and “two”) than for slightly larger ones (i.e., “three” and “four”). We discuss practical implications of these results for researchers studying numeracy and discuss further directions to assess the validity of the task.