Since pressure causes the attention to focus on a single direction, it can be inferred that pressure has a negative effect on visual lobe size. As a result, the probability that the target is found decreases. Eye movement is another factor that affects search performance and can be influenced by time pressure. When there exists time pressure, observers made smaller numbers of saccades per trial, the saccade amplitudes increased and fixation durations was shorter [11]. As a result, search efficiency was improved. However, the negative effect of eye movement change was that it became more difficulty for observers to distinguish target from background objects in dynamic condition. Erickson (1964) pointed out that for static search, peripheral visual acuity greatly affected search performance while central visual acuity mattered more in dynamic condition [13]. In low velocity conditions, the positive effect of time pressure was greater than the negative effect, thus performance was enhanced. On the contrary, the negative effect was greater than the positive effect in high velocity conditions, and this led to the performance decrease. Further study is needed to explore the effect of velocity and time pressure on eye movements.