Humphrey Bonnie, Helton William S, Bedoya Carol, Dolev Yinnon, Nelson Ximena J
School of Biological Sciences, University of Canterbury, Private Bag 4800, Christchurch, 8140, New Zealand.
Department of Psychology, University of Canterbury, Private Bag 4800, Christchurch, 8140, New Zealand.
Anim Cogn. 2018 Nov;21(6):787-794. doi: 10.1007/s10071-018-1210-2. Epub 2018 Aug 30.
The inability to maintain signal detection performance with time on task, or vigilance decrement, is widely studied in people because of its profound implications on attention-demanding tasks over sustained periods of time (e.g., air-traffic control). According to the resource depletion (overload) theory, a faster decrement is expected in tasks that are cognitively demanding or overstimulating, while the underload theory predicts steeper decrements in tasks that provide too little cognitive load, or understimulation. Using Trite planiceps, a jumping spider which is an active visual hunter, we investigated vigilance decrement to repetitive visual stimuli. Spiders were tethered in front of two stimulus presentation monitors and were given a polystyrene ball to hold. Movement of this ball indicates an attempt to turn towards a visual stimulus presented to a pair of laterally facing (anterior lateral) eyes for closer investigation with high acuity forward-facing (anterior median) eyes. Vigilance decrement is easily measured, as moving visual stimuli trigger clear optokinetic responses. We manipulated task difficulty by varying the contrast of the stimulus and the degree of 'noise' displayed on the screen over which the stimulus moved, thus affecting the signal:noise ratio. Additionally, we manipulated motivation by paired testing of hungry and sated spiders. All factors affected the vigilance decrement, but the key variable affecting decrement was stimulus contrast. Spiders exhibited a steeper decrement in the harder tasks, aligning with the resource depletion theory.
由于在持续较长时间的高要求注意力任务（如空中交通管制）中，无法随任务时间保持信号检测性能或警觉性下降这一现象具有深远影响，因此在人类中得到了广泛研究。根据资源耗竭（过载）理论，在认知要求高或过度刺激的任务中，预计警觉性下降会更快，而负荷不足理论则预测在提供认知负荷过少或刺激不足的任务中，警觉性下降会更明显。我们使用活跃的视觉猎手——跳蛛平额狡蛛，研究了对重复视觉刺激的警觉性下降。蜘蛛被拴在两个刺激呈现监视器前，并给它们一个聚苯乙烯球让其抓握。这个球的移动表明蜘蛛试图转向呈现给一对侧向（前外侧）眼睛的视觉刺激，以便用高敏锐度的向前（前中）眼睛进行更近距离观察。由于移动的视觉刺激会引发明显的视动反应，因此警觉性下降很容易测量。我们通过改变刺激的对比度以及刺激移动所经过屏幕上显示的“噪声”程度来操纵任务难度，从而影响信号与噪声的比例。此外，我们通过对饥饿和饱腹的蜘蛛进行配对测试来操纵动机。所有因素都影响了警觉性下降，但影响下降的关键变量是刺激对比度。在较难的任务中，蜘蛛表现出更明显的下降，这与资源耗竭理论相符。
