Tari Benjamin, Fadel Mohammed A, Heath Matthew
School of Kinesiology, The University of Western Ontario, London, ON, N6A 3K7, Canada.
Exp Brain Res. 2019 May;237(5):1195-1203. doi: 10.1007/s00221-019-05497-z. Epub 2019 Feb 26.
Executive function supports the rapid alternation between tasks for online reconfiguration of attentional and motor goals. The oculomotor literature has found that a prosaccade (i.e., saccade to veridical target location) preceded by an antisaccade (i.e., saccade mirror symmetrical to a target) elicits an increase in reaction time (RT), whereas the converse switch does not. This switch-cost has been attributed to the antisaccade task's requirement of inhibiting a prosaccade (i.e., response suppression) and transforming a target's coordinate (i.e., vector inversion)-executive processes thought to contribute to a task-set inertia that proactively interferes with the planning of a subsequent prosaccade. It is, however, unclear whether response suppression and vector inversion contribute to a task-set inertia or whether the phenomenon relates to a unitary component (e.g., response suppression). Here, the same stimulus-driven (SD) prosaccades (i.e., respond at target onset) as used in previous work were used with minimally delayed (MD) prosaccades (i.e., respond at target offset) and arranged in an AABB paradigm (i.e., A = SD prosaccade, B = MD prosaccade). MD prosaccades provide the same response suppression as antisaccades without the need for vector inversion. RTs for SD task-switch trials were longer and more variable than their task-repeat counterparts, whereas values for MD task-switch and task-repeat trials did not reliably differ. Moreover, SD task-repeat and task-switch movement times and amplitudes did not vary and thus demonstrate that a switch-cost is unrelated to a speed accuracy trade-off. Accordingly, results suggest the executive demands of response suppression is sufficient to engender the persistent activation of a non-standard task-set that selectively delays the planning of a subsequent SD prosaccade.
执行功能支持任务之间的快速切换，以便在线重新配置注意力和运动目标。眼动文献发现，在反扫视（即与目标呈镜像对称的扫视）之后出现的顺扫视（即扫视到真实目标位置）会导致反应时间（RT）增加，而相反的切换则不会。这种切换成本被归因于反扫视任务对抑制顺扫视（即反应抑制）和转换目标坐标（即矢量反转）的要求——这些执行过程被认为会导致任务集惯性，从而主动干扰后续顺扫视的计划。然而，尚不清楚反应抑制和矢量反转是否导致任务集惯性，或者该现象是否与单一成分（例如反应抑制）有关。在这里，使用了与之前工作中相同的刺激驱动（SD）顺扫视（即在目标出现时做出反应）以及最小延迟（MD）顺扫视（即在目标消失时做出反应），并将它们安排在AABB范式中（即A = SD顺扫视，B = MD顺扫视）。MD顺扫视提供了与反扫视相同的反应抑制，而无需矢量反转。SD任务切换试验的反应时间比任务重复试验更长且更具变异性，而MD任务切换和任务重复试验的值没有可靠差异。此外，SD任务重复和任务切换的运动时间和幅度没有变化，因此表明切换成本与速度准确性权衡无关。因此，结果表明反应抑制的执行需求足以导致非标准任务集的持续激活，从而选择性地延迟后续SD顺扫视的计划。
