To date, our understanding of how age affects the mind and brain is largely based on tightly controlled, though largely artificial, experimental tasks or, on the other hand, the completely uncontrolled resting state (Campbell & Schacter, 2016). But do these effects extrapolate to everyday life?
One way to approximate everyday life in the scanner is to use movies, which are arguably more similar to our experiences in everyday life than standard experimental stimuli. We scanned a large population-representative sample while they watched Alfred Hitchcock’s “Bang! You’re Dead” and found that neural synchrony, or the correlation between different people’s fMRI timecourses, decreases with age (Campbell et al., 2015). Older adults (particularly those with lessened attentional control) responded to the movie in a more idiosyncratic fashion than both younger adults and their age-matched peers, suggesting that our experience of events in everyday life become more individualistic as we age
The brain is thought to become less specialized with age. However, this view is largely based on findings of increased frontal activation during cognitive tasks which fail to separate task demands (e.g., attention, decision making) from the cognitive process under examination (e.g., language comprehension).
We recently used a novel systems-level approach to show that these compensatory activations may simply reflect age differences in response to the task itself (Campbell et al., 2016). Participants were scanned using fMRI during two versions of an experiment: a natural listening version in which they simply listened to spoken sentences and an explicit task version in which they decided if the sentences were grammatical. We found that while task-free language comprehension only activates the auditory and language networks (which do not differ with age), performing a simple task with the same sentences recruits additional domain-general networks. These findings challenge the conventional approach to neurocognitive aging by showing that the neural underpinnings of a given cognitive function depend on how you test it.
A prominent theory of cognitive aging suggests that older adults are less able to form new associations and this leads to poorer memory performance. Our work has challenged this view, suggesting that rather than a deficit in the binding process itself, older adults have difficulty limiting their attention to target information and this leads them to form more irrelevant associations.
Using multiple converging methods, we showed that older adults’ lessened control leads them to form associations between overlapping targets and distractors (Campbell, Hasher, & Thomas, 2010), learn statistical regularities contained entirely within distracting information, which younger adults do not learn (Campbell, Zimerman, Healey, Lee, & Hasher, 2012), and form wider associations over time when learning a list of words (Campbell, Trelle, & Hasher, 2014). While this “hyper-binding” may lead to greater interference on standard tests of associative memory (Biss, Campbell, & Hasher, 2012), it may also put older adults at an advantage when knowledge of real-world relationships is put to the test.