Production-comprehension asymmetries of semantic processing in Chinese older adults

Syntactic processing is essential to daily communication. It remains unclear how syntactic processing changes in both expressive and receptive modalities in older adults. The currentstudy aimed to determine whether older adults produce and comprehend sentences in an asymmetrical manner, namely superior production performance but inferior comprehension performance, or vice versa. Furthermore, we explored how it is affected by memory systems, as language is the interference of various basic cognitive abilities, especially the declarative and procedural memory systems(Ullman, 2001; Wang, 1982).Language and memory performance data were collected from 23 younger (aged 24.4±2.7 years; 13females) and 19 older (aged 68.1±2.6years; 9females)Chinese native speaker participants who were both cognitively normal.Participants were asked to complete a constrained production task, which requires them to construct sentences using words given to them. Two syntactic conditions were provided for the verbs that are capable of and are not capable of capturing the Ba construction. An assessment of receptive syntactic processing ability was conducted via the correctness judgment task. Participants were required to identify whether a Ba construction sentence with a word order violation is syntactically congruent or not, while the electroencephalogram (EEG) was recorded. Additionally, declarative memory and procedural memory were measured by the object recognition memory test and the serial reaction time test on two consecutive days. It was found that, regardless of the fact thatolder adults consumed much more time creating a sentence compared to their younger counterparts(t(40) = 3.015, p= .004), there was no significant difference between the two groups in terms of syntactic complexity, t(40) = .828, p= .413. Although both groups showed similar accuracy rates ofcomprehensiontasks(t(40) = -2.069, p= .05), the main group effect(F(1,40) = 11.55, p= .002)was noticed via the omnibus ANOVA on the mean amplitude of the anterior negativity(NA)componentelicited by the syntactic incongruent sentence compared to the congruent equivalent(Neville et al., 1991). Furthermore, a significant difference was found on older adults between the syntactic complexity and NA effects after min-max rescale(t(18) = -4.041, p= .0007), but not betweenthe thinking time and accuracy rate(t(18) = -0.698 , p= .494), suggesting that subtle production-comprehension asymmetry already permeated through the neural domains despite it being undetectable on the behavioral level. This potential asymmetry on the neural level may be due to lifelong divergent supports of declarative memory, since it was only correlated with production performance rather than comprehension performance.

Reference
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