Poster A65, Tuesday, August 20, 2019, 10:15 am – 12:00 pm, Restaurant Hall
Animacy in relative clauses differentially affects older adults’ speech processing
Ira Kurthen1, Martin Meyer1,2,3, Matthias Schlesewsky4, Ina Bornkessel-Schlesewsky4;1University of Zurich, 2Cognitive Psychology Unit (CPU), University of Klagenfurt, Austria, 3Tinnitus-Zentrum, Charité – Universitätsmedizin Berlin, 4Centre for Cognitive and Systems Neuroscience, University of South Australia, Adelaide
Age-related hearing loss (ARHL) is a condition affecting not only the inner ear, but also brain structure and function. ARHL impacts speech understanding on different levels, from transmission of the acoustic signal over its encoding to the extraction of meaning, but cognitive ability is consistently found to alleviate these negative effects. Most research focuses on the influence of ARHL and cognition on low-level features of the acoustic signal, e.g. background noise. However, ARHL has also been shown to influence understanding of embedded clauses. This research has focused mostly on comparing object-relative clauses (ORCs) to subject-relative clauses (SRCs), but ORCs are not per se more complex than SRCs. Indeed, the so-called ‘SRC advantage’ is only found with an animate subject in the main clause. Therefore, this study investigates the influence of ARHL and cognition on the processing of ORCs with respect to animacy. A sample of older monolingual native English speakers (aged 60-76) was presented acoustic sentences while their electroencephalogram was recorded. The sentences contained SRCs and ORCs with an animacy manipulation: 50% of each sentence type had an animate main clause subject and an inanimate relative clause subject, while the other 50% had an inanimate main clause subject and an animate relative clause subject. Participants rated the sentences on their acceptability. For the ORCs, event-related potentials (ERPs) time-locked to the onset of the relative clause subject were computed. Participants also performed cognitive tests tapping into working memory and inhibition, as well as a hearing threshold test. Significant differences in ERPs were investigated via cluster-based permutation tests. For analyses investigating the influence of participant-level factors (age, hearing loss, cognition), mean ERP voltage values for a baseline period and for the N400 time window (300 – 500 ms after onset) were extracted and linear mixed-effects models with random intercepts for participants and items were computed. Preliminary analyses with the first 17 participants showed that acceptability ratings were significantly lower for ORCs with an animate main clause subject than for all the other conditions. There was a significant difference at medial parieto-occipital electrodes between the ERPs in the N400 time window, with ERPs time-locked to the onset of the animate relative clause subject being more negative than ERPs time-locked to the onset of the inanimate relative clause subject. It was further investigated whether the N400 effect could be explained by participant-level factors. There were significant interaction effects between condition and age and condition and working memory, with higher age and lower working memory being related to higher N400 amplitudes. The ‘SRC advantage’ was present only for relative clauses with an animate main clause subject. Also, ORCs with an animate main clause subject elicited an N400 compared to ORCs with an inanimate main clause subject. This provides converging evidence for ORCs with an animate main clause subject being harder to process. Interestingly, age as well as working memory predicted N400 amplitude, suggesting that animacy in object-relative clauses differentially affects older adults’ speech processing, depending on their age and cognitive ability.
Themes: Speech Perception, Syntax
Method: Electrophysiology (MEG/EEG/ECOG)