Dissociative global and local task-switching costs across younger adults, middle-aged adults, older adults, and very mild Alzheimer’s disease individuals.

Abstract

A task-switching paradigm was used to examine differences in attentional control across younger adults, middle-aged adults, healthy older adults, and individuals classified in the earliest detectable stage of Alzheimer's disease (AD). A large sample of participants (570) completed a switching task in which participants were cued to classify the letter (consonant/vowel) or number (odd/even) task-set dimension of a bivalent stimulus (e.g., A 14), respectively. A Pure block consisting of single-task trials and a Switch block consisting of nonswitch and switch trials were completed. Local (switch vs. nonswitch trials) and global (nonswitch vs. pure trials) costs in mean error rates, mean response latencies, underlying reaction time distributions, along with stimulus-response congruency effects were computed. Local costs in errors were group invariant, but global costs in errors systematically increased as a function of age and AD. Response latencies yielded a strong dissociation: Local costs decreased across groups whereas global costs increased across groups. Vincentile distribution analyses revealed that the dissociation of local and global costs primarily occurred in the slowest response latencies. Stimulus-response congruency effects within the Switch block were particularly robust in accuracy in the very mild AD group. We argue that the results are consistent with the notion that the impaired groups show a reduced local cost because the task sets are not as well tuned, and hence produce minimal cost on switch trials. In contrast, global costs increase because of the additional burden on working memory of maintaining two task sets.

The developmental trajectories of executive function from adolescence to old age

“…A predicted cubic age relationship would indicate a developmental improvement in EF in adolescence through to young adulthood, a decline in EF across adulthood, and a further steeper decline in EF in older age. Finally, in line with previous research (e.g., 84 ) we predicted that the different aspects of cognitive flexibility would should show distinct effects: we predicted that switching costs (i.e., changing task sets) would not show any age-related changes, but mixing costs (i.e., maintaining multiple task sets) would show an increase across adulthood (e.g., 84,85 ).…”

“…Mixing costs have generally been found to be greater in older adults (e.g., [54][55][56][57][58] ) there are mixed results in regard to switch costs, with some studies reporting an age-related increase (e.g., 59 ), a U-shaped trajectory 53 or no age-related differences (e.g., 58,59 ), most likely due to differences in the task switching paradigms. We note that the current study used an alternating-runs paradigm without a preparatory cue-stimulus interval, which is analogous to Huff et al 's 84 task-switching paradigm with comparable aging results. In addition, switch and mixing costs showed a negative correlation, reflecting that individuals with a greater switch cost also had a reduced mixing cost, and vice versa, and this pattern also remained when accounting for the effect of age.…”

Switching between reading tasks leads to phase-transitions in reading times in L1 and L2 readers

“…Furthermore, elaborations of designs and modeling strategy have furrowed the notion of switching costs into ever finer scales of time and rooted them in finer subdivisions of the cognitive system. For instance, as experimenters have tested task switching not just across block but also within block, they need to distinguish between global and local costs of switching, respectively [82] or, by another-yet-synonymous set of labels, switching costs and mixing costs, respectively [83]. Local/mixing costs may reflect that trial-by-trial variation in the task set never permits full reconfiguring the task set, and more global/switching costs may come from maintaining multiple tasks sets [82], but the costs of having to inhibit interfering task-stimulus relationships seem to accrue across time, no matter their source [84].…”

Evaluating Cognitive Relationships with Resting-State and Task-driven Blood Oxygen Level-Dependent Variability

“…In addition to the neuropsychological test batteries, participants also completed a battery of computerized attentional (Spieler, Balota, & Faust, 1996;Stroop, 1935), a Simon spatial interference task (Castel, Balota, Hutchison, Logan, & Yap, 2007;Simon, 1969), and a consonant-vowel/oddeven (CVOE) task-switching task (Huff, Balota, Minear, Aschenbrenner, & Duchek, 2015).…”