When we follow a slowly moving target with our eyes, we perform smooth pursuit eye movements (SPEM). Previous investigations point to significantly and robustly reduced SPEM performance in the presence of a stationary background and at higher compared to lower target velocities. However, the reliability of these background and target velocity effects has not yet been investigated systematically.

To address this issue, 45 healthy participants (17 m, 28 f) took part in two experimental sessions 7 days apart. In each session, participants were instructed to follow a horizontal SPEM target moving sinusoidally between ±7.89° at three different target velocities, corresponding to frequencies of 0.2, 0.4 and 0.6 Hz. Each target velocity was presented once with and once without a stationary background, resulting in six blocks. The blocks were presented twice per session in order to additionally explore potential task length effects. To assess SPEM performance, velocity gain was calculated as the ratio of eye to target velocity.

In line with previous research, detrimental background and target velocity effects were replicated robustly in both sessions with large effect sizes. Good to excellent test-retest reliabilities were obtained at higher target velocities and in the presence of a stationary background, whereas lower reliabilities occurred with slower targets and in the absence of background stimuli. Target velocity and background effects resulted in largely good to excellent reliabilities.

These findings not only replicated robust experimental effects of background and target velocity at group level, but also revealed that these effects can be translated into reliable individual difference measures.

当我们用眼睛跟随一个缓慢移动的目标时，我们会进行平滑追踪眼动 (SPEM)。先前的研究表明，在存在静止背景的情况下，与较低的目标速度相比，SPEM 性能显着下降。然而，尚未系统地研究这些背景和目标速度效应的可靠性。

为了解决这个问题，45 名健康参与者（17 m，28 f）参加了两个相隔 7 天的实验。在每次会议中，参与者都被指示跟随水平 SPEM 目标以三个不同的目标速度在 ±7.89° 之间正弦移动，对应于 0.2、0.4 和 0.6 Hz 的频率。每个目标速度在有和没有固定背景的情况下呈现一次，从而产生六个块。块在每个会话中呈现两次，以进一步探索潜在的任务长度影响。为了评估 SPEM 性能，速度增益被计算为眼睛与目标速度的比率。

与之前的研究一致，有害的背景和目标速度效应在两个具有大效应量的会话中都得到了有力的复制。在较高的目标速度和存在静止背景的情况下获得了良好到出色的重测可靠性，而在较慢的目标和没有背景刺激的情况下，可靠性较低。目标速度和背景效应在很大程度上产生了良好到极好的可靠性。

这些发现不仅在群体水平上复制了背景和目标速度的强大实验效果，而且还表明这些效果可以转化为可靠的个体差异测量。