In this study, the effect of presentation rates on pupil dilation is investigated for target recognition in the Rapid Serial Visual Presentation (RSVP) paradigm. In this experiment, the RSVP paradigm with five different presentation rates, including 50, 80, 100, 150, and 200 ms, is designed. The pupillometry data of 15 subjects are collected and analyzed. The pupillometry results reveal that the peak and average amplitudes for pupil size and velocity at the 80-ms presentation rate are considerably higher than those at other presentation rates. The average amplitude of pupil acceleration at the 80-ms presentation rate is significantly higher than those at the other presentation rates. The latencies under 50- and 80-ms presentation rates are considerably lower than those of 100-, 150-, and 200-ms presentation rates. Additionally, no considerable differences are observed in the peak, average amplitude, and latency of pupil size, pupil velocity, and acceleration under 100-, 150-, and 200-ms presentation rates. These results reveal that with the increase in the presentation rate, pupil dilation first increases, then decreases, and later reaches saturation. The 80-ms presentation rate results in the largest point of pupil dilation. No correlation is observed between pupil dilation and recognition accuracy under the five presentation rates.

For this research, electroencephalography (EEG) was analyzed to investigate the perception ability of the brain for moving objects at different speeds. In this experiment, total six kinds of videos regarding license plates were created, moving at distinct speed of 0.26 m/s, 0.36 m/s, 0.46 m/s, 0.56 m/s, 0.66 m/s, and 0.76 m/s, respectively. In the semantic priming paradigm, the N400 effect was analyzed for each speed. The ERP results demonstrated that the N400 amplitude gradually reduced with increasing speed. At the three lower speeds, N400 was evoked evidently and mainly distributed in the centro-posterior region. At the three higher speeds, no significant N400 effect was found. The results concluded that the perception ability of the brain declined with the acceleration of the object’s moving speed and that the brain recognized the detailed information of the moving object when its speed was lower than 0.46 m/s.