Strategy and Motivation, Rather Than Fatigue, Drive Age-Related Differences in Sustained Attention Performance: Evidence for Decoupled Beta-Band Oscillations.

Young and older adults adopted distinct speed-accuracy trade-off strategies from the outset that remained stable throughout the experiment.

• Young adults (mean age = 22.6 years, n = 18) showed faster but more erroneous responses.
• Older adults (mean age = 66.5 years, n = 16) showed slower but more accurate responses.
• These strategy differences were present from the beginning of the task and remained stable over the course of the experiment.
• Response strategies did not change over time-on-task within either group.

Subjective fatigue increased with time-on-task irrespective of age group.

• Both young and older adults reported increasing subjective fatigue across the experiment.
• The increase in subjective fatigue was not specific to either age group.
• Despite rising subjective fatigue, behavioral performance strategies remained stable.

Two distinguishable poststimulus beta-band EEG signatures were identified with distinct topographies and functional roles.

• The first beta signature had a fronto-central topography and served as a marker of age-specific response strategy.
• The second beta signature had a fronto-parietal topography and was modulated by motivation per se.
• These two beta signatures were described as 'decoupled,' indicating they reflect separable neural processes.
• The authors speculate these two signatures contribute to offsetting performance declines over time.

A financial incentive manipulation in the final block modulated fronto-parietal beta activity associated with motivation.

• In the final block, half of the participants in each group were offered a financial incentive for best overall performance.
• This motivational manipulation was reflected specifically in the fronto-parietal beta signature.
• The fronto-central beta signature was not modulated by the motivational incentive, indicating specificity of the two beta signals.

Prestimulus alpha power and mind-wandering scores increased with time-on-task, but were not correlated with each other.

• Both prestimulus alpha power and self-reported mind-wandering scores increased as the task progressed.
• No significant correlation was identified between prestimulus alpha power and mind-wandering scores.
• This dissociation suggests these two commonly used measures of attentional lapses may not index the same underlying process.

The study used the Sustained Attention to Response Task (SART) with simultaneous EEG recording to induce and measure fatigue across age groups.

• 18 young participants (mean age = 22.6 years) and 16 older participants (mean age = 66.5 years) were recruited.
• EEG was recorded simultaneously during the SART to capture both prestimulus and poststimulus neural activity.
• The final block included a between-subjects motivational manipulation (financial incentive vs. no incentive) within each age group.
• Measures included behavioral performance (speed and accuracy), subjective fatigue ratings, mind-wandering scores, and EEG oscillatory activity.