Moran Catherine N, McGovern David P, Melnychuk Mike, Smeaton Alan F, Dockree Paul M
Trinity College Institute of Neuroscience & School of Psychology, Trinity College Dublin, Dublin, Ireland.
School of Population Health, RCSI University of Medicine & Health Sciences, Dublin, Ireland.
Hum Brain Mapp. 2025 Apr 15;46(6):e70174. doi: 10.1002/hbm.70174.
This study traced the neurophysiological signals of fluctuating attention and task-related processing to ascertain the mechanistic basis of transient strategic shifts between competing task focus and mind-wandering, as expressed by the 'exploitation/exploration' framework, and explored how they are differentially affected with age. Thirty-four younger (16 female, mean age 22 years) and 34 healthy older (20 female, mean age 71 years) adults performed the Gradual Contrast Change Detection task; monitoring a continuously presented flickering annulus for intermittent gradual contrast reductions and responding to experience sampling probes to discriminate the nature of their thoughts at discrete moments. Electroencephalography and pupillometry were concurrently recorded during target- and probe-related intervals. Older adults tracked the downward stimulus trajectory with greater sensory integrity (reduced target SSVEP amplitude) and demonstrated earlier initiation of evidence accumulation (earlier onset CPP), attenuated variability in the attentional signal (posterior alpha) and more robust phasic pupillary responses to the target, suggesting steadier attentional engagement with age. Younger adults only exhibited intermittent sensory encoding, indexed by greater variability in the sensory (SSVEP) and attentional (alpha) signals before mind-wandering relative to focused states. Attentional variability was accompanied by disrupted behavioural performance and reduced task-related neural processing, independent of age group. Together, this elucidates distinct performance strategies employed by both groups. Older adults suspended mind-wandering and implemented an exploitative oscillation strategy to circumvent their reduced cognitive resources and allay potential behavioural costs. Conversely, younger adults exhibited greater exploration through mind-wandering, utilising their greater cognitive resources to flexibly alternate between competing goal-directed and mind-wandering strategies, with limited costs.
本研究追踪了注意力波动和任务相关加工的神经生理信号，以确定在相互竞争的任务焦点和走神之间瞬时策略转换的机制基础，这一转换由“开发/探索”框架所表达，并探究了年龄对其的不同影响。34名年轻成年人（16名女性，平均年龄22岁）和34名健康的年长成年人（20名女性，平均年龄71岁）进行了渐变对比度变化检测任务；监测持续呈现的闪烁环形物，以检测间歇性的渐变对比度降低，并对经验抽样探针做出反应，以辨别他们在离散时刻的思维性质。在与目标和探针相关的时间段内同时记录脑电图和瞳孔测量数据。年长成年人以更高的感觉完整性追踪向下的刺激轨迹（目标稳态视觉诱发电位幅度降低），并表现出更早开始证据积累（较早出现的对侧后顶叶正波），注意力信号（后部阿尔法波）的变异性减弱，以及对目标更强烈的阶段性瞳孔反应，这表明随着年龄增长注意力参与更稳定。年轻成年人仅表现出间歇性的感觉编码，表现为在走神前相对于专注状态，感觉（稳态视觉诱发电位）和注意力（阿尔法波）信号的变异性更大。注意力变异性伴随着行为表现受损和与任务相关的神经加工减少，且与年龄组无关。总之，这阐明了两组所采用的不同表现策略。年长成年人暂停走神并实施一种开发性振荡策略，以规避其减少的认知资源并减轻潜在的行为成本。相反，年轻成年人通过走神表现出更大的探索性，利用其更丰富的认知资源在相互竞争的目标导向和走神策略之间灵活交替，且成本有限。
