Language comprehension across the life span: Introduction to the special section

Over the last years, cognitive aging has attracted a great deal of scholarly attention, partly due to the global demographic trend toward aging populations and the economic, medical, and social challenges this poses. Cognitive aging in healthy individuals is often seen as a process of general cognitive decline. Aging is known to be associated with losses of cerebral mass, decline of gray and white matter integrity, disruption of functional brain networks, and decrements in neuroplasticity (ability of the brain to reorganize itself in response to injury, disease, or new experiences). These structural and functional brain changes have widely been taken to underlie a general deterioration of cognitive functions including episodic and working memory, executive control, and language processing (Borella et al., 2011; see Burke & Shafto, 2008, for a review).

More recently, however, different strands of research have begun to cast doubt on the tenet of general cognitive decline. Thus, a number of studies have argued that at least certain aspects of cognition (including vocabulary size, world knowledge, explicit memory during learning, and different aspects of language comprehension) might actually be preserved or even improve as a function of age (Engel & Hanulíková, 2020; Eppinger et al., 2010; Ferstl, 2006; Hanulíková, 2020; Lockhart et al., 2014; Radvansky & Dijkstra, 2007; Ramscar et al., 2014; Wlotko et al., 2010). Prior studies concluding to cognitive deterioration have been criticized for not duly taking into consideration the trade-off between amount of stored information (which increases as a function of age) and processing speed (which may also slow down as a function of higher information load; Gray & Hills, 2014; Ramscar et al., 2014).

It has also been argued that many age-related differences identified in behavioral or neuro-functional experiments might simply have resulted from weaker responsiveness of older subjects to task demands in unnatural experimental situations (Campbell et al., 2012; Davis et al., 2014). More generally, it has been suggested that age should not be seen as “a situation where older individuals simply do the same task more poorly than younger individuals” (Gray & Hills, 2014, p. 2), but as a situation where younger and elderly subjects may to some extent recruit different cognitive strategies and neural resources to support a similar level of behavioral performance (Bailey & Zacks, 2015; Martins et al., 2015; Meunier et al., 2014; Shafto & Tyler, 2014; Wlotko et al., 2010).

This special section makes a step toward gaining a more systematic and integrated understanding of the dynamics of language comprehension across the life span at different levels of language processing. It is based on the results of a Project Group on the same topic, awarded by the Freiburg Institute for Advanced Studies (FRIAS) to the editors of this section. The project was hosted by the FRIAS from 2016 to 2018 and concluded with a workshop in April 2018. Bringing together international researchers across various disciplines (psychology, neurology, linguistics, cognitive sciences, among others), the workshop explored challenges and opportunities of life span research on language comprehension.

More specifically, the present special section aimed to address several questions arising from the stimulating discussions around the presumed resilience of language comprehension to aging: Are all aspects of language comprehension (phonological, morphological, syntactic, semantic, pragmatic levels of processing) equally spared across the (adult) life span? Does broadly similar behavioral performance between age-groups in comprehension tasks result from similar neuro-functional processes, or does the performance of elderly people rest on compensatory reorganization of the language comprehension system? How do the dynamics between language and other cognitive functions (executive control, working memory) develop with age? How do sensory deficits affect language comprehension? How do typical experimental tasks (e.g., button-press tasks under time pressure, tasks with high working memory load) affect, and maybe even bias, the outcome of cognitive experiments comparing younger and older subjects?

This special section brings together five contributions that cover diverse age-groups from primary school children to older adults. It features three original research papers and two reviews which are concerned with various subprocesses of language comprehension, going from speech perception to higher level text comprehension. To provide answers to the above questions from different perspectives, they employ diverse methods, making use of longitudinal and cross-sectional data designs, behavioral and neurophysiological data (e.g., sentence recall, functional Magnetic Resonance Imaging (fMRI), reaction times, acceptability ratings), and diverse statistical approaches (e.g., structural equation modeling, mixed effects regression).

The review by Heinrich (2021) addresses the role of cognition in speech-in-noise (SiN) processing across the life span. The age variable is particularly relevant to this issue, since aging is accompanied by both cognitive and auditory changes. However, the author cautions against overly simplistic expectations by highlighting that in SiN processing, age-cognition relationships interact in complex ways with further variables such as the listening situation and the use of hearing aids. Against this background, the article suggests promising theoretical and experimental avenues for further research.

In text comprehension research, the notion of situation model has been influential. Besides a representation of the wording of the text, the result of comprehension is an integration of the verbal information with background knowledge and context information. Hoeben Mannaert and Dijkstra (2021) use the event segmentation model as a theoretical framework for reviewing experimental work on situation model generation and updating in older adults. The authors conclude that these higher level language processes remain largely intact across the life span, even though declines in working memory and processing speed pose additional challenges.

Krebs et al. (2021) explore how age and age of acquisition (AoA) influence acceptability ratings and reaction times in deaf signers of Austrian Sign Language processing different kinds of sign language constructions. While age is found to positively correlate with response times, relationships between AoA and acceptability ratings turn out to be much more intricate, with the direction of effects depending on the specific linguistic construction at hand.

Diaz and Yalcinbas (2021) study the neuronal underpinnings of age-related changes in speech perception and interpretation. Using fMRI, they employ the McGurk effect, a well-known paradigm to study the integration of auditory and visual information into a unified percept. The behavioral data show a similar effect in older (around 65 years of age) and younger adults (25 years on average). Interestingly, the neuroimaging data reveal that the older group relied more on brain regions involved in attentional and monitoring processes, lending support to the idea of compensatory strategies.

The empirical study by Acha et al. (2021) addresses the dynamic interaction between memory and linguistic skills during child language development. Using a longitudinal design, children’s working memory and sentence recall abilities are tracked at the ages 6 and 7. The authors report robust predictive effects of memory or linguistic skills on recall performance within each test time. Moreover, the phonological short-term memory and sentence recall performance at the age of 6 predict verbal working memory and vocabulary skills 1 year later.

Taken together, the articles featured in this special section provide an important step toward a more comprehensive understanding of the complex dynamics between language and other cognitive functions across the life span from different perspectives.