I research which aspects of speaking and understanding language are affected by healthy ageing and study variability among healthy older adults in ageing trajectories. In speaking, for example, I have found that older adults show a decline when producing words (e.g., older adults experience tip-of-the-tongue states to varying degrees, and older adults show a decline in lexical access when planning phrases). Also, language comprehension shows a decline with ageing; for example, older adults show a decline in morpho-syntactic processing during listening. Age-related changes in performance are associated with changes in brain health. I evaluate models of maintenance, compensation, and reserve to gain a better understanding of how changes in brain health contribute to language abilities in older age.
Selected publications:
Rahman, R., Tsvetanov, K. A., Feron, J., Mullinger, K., Joyce, K., Gilani, A., Fernandes, E. G., Wetterlin, A., Wheeldon, L., Lucas, S. J. E., Segaert, K. Lifestyle and brain health determinants of word-finding failures in healthy ageing. Preprint available: https://doi.org/10.1101/2023.12.08.570799
Poulisse, C., Wheeldon, L., Segaert, K. (2019). Evidence against preserved syntactic comprehension in healthy aging.
Journal of Experimental Psychology: Learning, Memory and Cognition,45(12), 2290–2308 (PDF)
Segaert, K., Lucas, S.J.E., Burley, C.V., Segaert, P., Milner, A.E., Ryan, M., Wheeldon, L. (2018) Higher physical fitness levels are associated with less language decline in healthy ageing. Scientific Reports, 8:6715. doi: 10.1038/s41598-018-24972-1 (PDF)
Selected media on tip-of-the-tongue states: The Conversation, New York Times, The Telegraph, WebMD, MedicalXpress, Science Daily, Daily Mail; on language and Alzheimer's dementia: The Independent,Science Daily,Gulf Times, New Zealand Herald, MedicalXpress.
I research the impact of cognitive training and regular exercise interventions for brain health, cognition and language functions. Especially regular exercise interventions seem particularly promising. In a home-based HIIT intervention, older adults do not only improve their cardiorespiratory fitness levels, but monolingual older adults improve their language comprehension skills also.
Selected publications:
Fernandes, E; Fosstveit, S. H.; Feron, J.; Rahman, F.; Lucas, S. J. E.; Lohne-Seiler, H.; Berntsen, S.; Wetterlin, A.; Segaert, K.; Wheeldon, L. (2024) Effects of exercise training on language comprehension in monolingual and bilingual older adults: A randomized controlled trial. Aging, Neuropsychology and Cognition, 1-33. (PDF)
Feron, J., Rahman, F., Fosstveit, S., Joyce, K.E., Gilani, A., Lohne-Seiler, H., Berntsen, S., Mullinger, K., Segaert, K., Lucas, S. (2024) Cerebral blood flow and arterial transit time responses to home-based exercise training in healthy older adults. (PDF)
Being bilingual or multilingual offers some advantages in terms of being able to communicate in more than one language. However, it comes with some challenges as well: code-switching, for example (this is changing from one language to another), requires flexibility and cognitive control. Bilingualism is often thought, therefore, to be associated with greater inhibition and task-switching abilities, and may offer some protection against age-related decline. I work on characterizing which aspects of a bilingual's profile (language proficiency, age of second language acquisition, and language use) lead to changes in non-linguistic and linguistic cognitive processing, and to functional and structural brain changes (see here for a great background article in The Conversation by a postdoc on one of our projects).
Selected publications:
DeLuca, V., Voits, T., Ni, J., Carter, F., Rahman, F., Mazaheri, A., Krott, A., Segaert, K. (2024) Mapping individual aspects of bilingual experience to adaptations in brain structure. Cerebral Cortex, 34, bhae029 (PDF)
Markiewicz, R., Rahman, F., Fernandes, E., Limachya, R., Wetterlin, A., Wheeldon, L. and Segaert, K. (2024) Effects of healthy ageing and bilingualism on attention networks. Bilingualism, Language and Cognition, 2024: 1-14. (PDF)
Fernandes, E., Segaert, K., Rahman, F., Wetterlin, A., Wheeldon, L. (2024) Bilingualism and ageing independently impact on language processing: evidence from comprehension and production. Bilingualism, Language and Cognition, 2024:1-15 (PDF)
DeLuca, V., Segaert, K., Mazaheri, A., & Krott, A. (2020) Understanding bilingual brain function and structure changes? U Bet! A Unified Bilingual Experience Trajectory model. Journal of Neurolinguistics, 56, 100930 (PDF)
I conduct fMRI, EEG, ECoG, MEG, and OPM studies on sentence comprehension and sentence production. I have shown that the neurobiological substrate for sentence-level syntactic and semantic processing is shared for speaking and listening. EEG, MEG, and ECoG studies have yielded a precise picture of how the brain implements syntactic and semantic binding through precisely timed mechanisms. I have also collaborated on EEG studies investigating the effects of prediction during language comprehension.
Selected publications:
Hardy, S., Jensen, O., Wheeldon, L., Mazaheri, A., Segaert, K. (2022) Modulation in alpha band activity reflects syntax composition: An MEG study of minimal syntactic binding. Cerebral Cortex, doi:bhac080. (PDF)
Nieuwland, M. et al. (2020) Dissociable effects of prediction and integration during language comprehension: Evidence from a large-scale study using brain potentials. Philosophical Transactions of the Royal Society B, 375(1791), 20180522. (PDF)
Sharoh, D., van Mourik, T., Bains, L.J., Segaert, K., Weber, K., Hagoort, P., Norris, D. (2019). Laminar specific fMRI reveals directed interactions in distributed networks during language processing. Proceedings of the National Academy of Sciences Sep 2019, 201907858; DOI: 10.1073/pnas.1907858116 (PDF)
Segaert, K., Menenti, L., Weber, K., Petersson, K. M., & Hagoort, P. (2012). Shared syntax in language production and language comprehension — An fMRI study. Cerebral Cortex, 22, 1662-1670. (PDF)
Syntactic priming is a paradigm often used in behavioural experiments on syntactic processing. I am interested in how syntactic preferences determine syntactic priming effects, and how priming effects in syntactic choices relate to priming effects in reaction times. The combination of these gives unique insights into how we generate sentences. I also examine the persistence and generalizability of syntactic priming effects, as this gives us invaluable information about the mechanisms driving syntactic priming effects (and more generally, syntactic production) in both young and older adults.
Selected publications:
Heyselaar, E. & Segaert, K. (2022) Structural priming persists for (at least) one month in young adults, but not in healthy older adults. Journal of Experimental Psychology: Learning, Memory and Cognition. (PDF)
Heyselaar, E., Wheeldon, L., & Segaert, K. (2021). Structural priming is supported by different components of non-declarative memory: Evidence from priming across the lifespan. JEP:LMC. (PDF)
Hardy, S., Wheeldon, L., Segaert, K. (2020). Structural priming is determined by global syntax rather than internal phrasal structure: Evidence from young and older adults. Journal of Experimental Psychology: Learning, Memory and Cognition, 46(4), 720–740. https://doi.org/10.1037/xlm0000754 (PDF)
Segaert, K., Wheeldon, L. & Hagoort, P. (2016) Unifying structural priming effects on syntactic choices and timing of sentence generation. Journal of Memory and Language, http://dx.doi.org/10.1016/j.jml.2016.03.011. (PDF)
Language processing is most often studied in experiments with one participant doing a language task. But of course, in daily life, language is most often used in a communicative setting with a conversation partner. My research has shown that core language processes, like syntax, are influenced by the communicative and social context in which they take place, possibly through a mechanism of attention allocation. I also research the neural mechanisms that support cooperation between two people (communication is one example of a cooperative task).
Selected publications:
Markiewicz, R., Rahman, F., Apperly, I., Mazaheri, A., & Segaert, K. (2024). It’s not all about you: Communicative cooperation is determined by your partner’s theory of mind abilities as well as your own. Journal of Memory and Language: Learning, Memory and Cognition, 50(5), 833–844. (PDF)
Markiewicz, R.,Segaert, K., Mazaheri, A. (2024) Brain-to-brain coupling forecasts future joint action outcomes. IScience, Volume 27, Issue 9, 110802https://doi.org/10.1016/j.isci.2024.110802 (PDF)
Schoot, L., Hagoort, P., Segaert, K. (2019) Stronger syntactic alignment in the presence of an interlocutor. Frontiers in Psychology, 10: 685. doi: 10.3389/fpsyg.2019.00685 (PDF)
Heyselaar, E., Hagoort, P., & Segaert, K. (2017) How social opinion influences syntactic processing - an investigation using Virtual Reality. PLoS One, 12(4): e0174405. https://doi.org/10.1371/journal (PDF)
I examine how language is processed by older adults with mild cognitive impairment, and whether variability in language processing within those with mild cognitive impairment is informative for predicting conversion to Alzheimer's disease.
Selected publications:
Segaert, K., Poulisse, C., Markiewicz, R., Wheeldon, L., Marchment, D., Adler, Z., Howett, D.5 Chan, D., Mazaheri, A. (2021) Detecting impaired language processing in patients with mild cognitive impairment using around-the-ear cEEgrid electrodes. Psychophysiology, 00, e13964. https://doi.org.10.1111/psyp.13964 (PDF)
Segaert, K., Mazaheri, A., Olichney, J., Niu, J.-Q., Yang, J.-C., Shapiro, K., Bowman, H. (2018) EEG oscillations during word processing predict MCI conversion to Alzheimer’s disease. NeuroImage Clinial, 17, 188-197. https://doi.org/10.1016/j.nicl.2017.10.009 (PDF)
Selected media on language and Alzheimer's dementia: The Independent,Science Daily,Gulf Times, New Zealand Herald, MedicalXpress.