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Saccadic eye movements enable us to search for the target of interest in a crowded scene or, in the case of goal-directed saccades, to simply bring the image of the peripheral target to the very centre of the fovea. This mechanism extends the use of the superior image processing performance of the fovea over a large visual field. We know that visual information is processed quickly at the end of each saccade but estimates of the times involved remain controversial. This study aims to investigate the processing of visual information during post fixation oscillations of the eyeball. A new psychophysical test measures the combined eye movement response latencies, including fixation duration and visual processing times. When the test is used in conjunction with an eye tracker, each component that makes up the ‘integrated saccade latency’ time, from the onset of the peripheral stimulus to the correct interpretation of the information carried by the stimulus, can be measured and the discrete components delineated. The results show that the time required to process and encode the stimulus attribute of interest at the end of a saccade is longer than the time needed to carry out the same task in the absence of an eye movement. We propose two principal hypotheses, each of which can account for this finding. 1. The known inhibition of afferent retinal signals during fast eye movements extends beyond the end point of the saccade. 2. The extended visual processing times measured when saccades are involved are caused by the transient loss of spatial resolution due to eyeball instability during post-saccadic oscillations. The latter can best be described as retinal image smear with greater loss of spatial resolution expected for stimuli of low luminance contrast.

扫视眼动（saccadic eye movement）能够让我们在拥挤场景中搜寻目标物；而就目标导向性扫视而言，其作用是将外周视野内的目标影像精准投射至中央凹（fovea）的中心区域。该机制可使中央凹卓越的图像处理性能在广阔视野范围内得到充分利用。已知视觉信息会在每次扫视结束后得到快速处理，但针对该过程所需时长的估算仍存在争议。本研究旨在探究注视后眼球振荡期间的视觉信息处理过程。本研究设计了一种全新的心理物理测试（psychophysical test），用于测量包含注视时长与视觉处理时长在内的综合眼动反应潜伏期。当该测试与眼动追踪仪（eye tracker）联用时，可对构成“整合扫视潜伏期”的各组分进行精准测量与清晰界定——该潜伏期指从外周刺激（peripheral stimulus）出现到对刺激所携带信息做出正确解读的总时长。研究结果显示，在扫视结束后处理并编码目标刺激属性所需的时长，要长于无眼动参与时完成同类任务的时长。针对该实验结果，本研究提出两项核心假说，均可对其做出合理解释：1. 已知快速眼动期间传入视网膜信号受到的抑制作用会延续至扫视结束之后；2. 伴随眼动出现的视觉处理时长延长，是由扫视后眼球振荡期间眼球不稳定导致的空间分辨率（spatial resolution）暂时性下降所引发的。后者可被具象化为视网膜影像模糊，且低亮度对比度（luminance contrast）的刺激会伴随更显著的空间分辨率损失。