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Tagging speech planning and comprehension across the lifespan
Poster Session D, Thursday, October 1, 4:30 - 6:30 pm, Wangari Maathai
This poster is part of the Sandbox Series.
Cecilia Husta1, Linda Drijvers2, Antje Meyer1; 1Max Planck Institute for Psycholinguistics, 2Donders Institute for Brain, Cognition and Behaviour
Most current evidence on how people plan speech during comprehension comes from younger adults, who are typically healthy and highly educated. A consistent finding in this population is that speech planning is a highly flexible process that can be initiated rapidly and can co-occur with other linguistic and nonlinguistic processes with relatively little interference. Older adults, however, differ from younger adults in working memory capacity, processing speed, and linguistic knowledge. These differences may not only lead to slower or less accurate speech production, but may also reflect qualitative changes in the planning process itself. Understanding how people plan and comprehend language in real time therefore requires methods that can track and dissociate both processes with high temporal precision. Rapid Invisible Frequency Tagging (RIFT) is well suited for this purpose because it measures steady-state evoked potentials (SSEPs) to continuous visual and auditory stimulation, providing an index of attentional engagement. In the present study, 30 younger and 30 older healthy Dutch participants will view pictures depicting adjectives (e.g., wet) and nouns (e.g., dog) while listening to questions about categorically related nouns (e.g., What matches with the grey bunny?). The luminance of the adjective and noun pictures will be modulated at high frequencies (64 and 68Hz, counterbalanced across stimuli), while the amplitude of the auditory questions will be modulated at 54Hz. These imperceptible modulations allow us to track attention to the visual and auditory streams unobtrusively. In the simple naming condition, participants will name only the noun (e.g., dog), whereas in the complex naming condition they will produce both the adjective and noun (e.g., wet dog). Note that data collection will begin in June. We expect stronger visual tagging responses in the complex naming condition, particularly at the adjective-tagging frequency, reflecting increased lexical retrieval and combinatorial planning demands. We further predict later and broader visual tagging responses in older than younger adults, consistent with slower lexical access and prolonged planning. In contrast, auditory tagging responses are expected to be weaker in the complex naming condition, reflecting reduced resources for concurrent speech comprehension during more demanding speech planning. Importantly, RIFT also enables investigation of neural interactions between visual and auditory representations. Coupling between tagged stimuli gives rise to intermodulation frequencies, reflecting nonlinear interactions between the base tagging frequencies (e.g., 68−54Hz, 64−54Hz, and 68−64Hz). We expect stronger intermodulation frequencies between adjective and noun representations in the complex naming condition, reflecting lexical integration into a single utterance. In contrast, interactions between the auditory stimulus and noun representation may be stronger in the simple naming condition, where reduced production demands leave more resources for auditory processing. Intermodulation frequencies may also differ in older adults, potentially reflecting greater overlap between the comprehension and production pathways. Together, these findings would provide novel insight into how language production and comprehension interact dynamically across the lifespan. More broadly, the study demonstrates how RIFT can be used to disentangle concurrent cognitive processes with high temporal precision, offering a powerful tool for investigating age-related changes in attention and speech planning.
Topic Areas: Language Production, Methods