장시간 동적 시자극 노출에 따른 동공 반응

Abstract

The mechanism of pupillary responses in previous studies has been investigated by response patterns to static visual stimuli in a small amount of time. However, this method is likely to be limited to explain the changes of pupillary responses when an individual is exposed to prolonged dynamic visual stimuli. Thus, this study aims to inspect the patterns of pupillary responses in humans with normal vision according to the prolonged exposure of video, and to examine the relationship between the video features and each pupillary response. A total of 54 individuals, aged 14-67 years, participated, however, one participant was excluded in the data analysis due to errors in pupillary data. A documentary and a music video with a length of 45 minutes were used, and the three levels of average display luminance within the range of standard television (150/200/300nit) were applied to provide a diversity of visual stimuli. The viewing condition was that the participants watched the videos at 2.1m away from the 55’’ TV under the ambient illuminance of 200lux, and simultaneously the pupil data were collected by an eye-tracker. In order to study the effects of age on the responses, the participant were divided into three age groups: adolescents (10-19 years old), younger adults (20-39 years old), and older adults (40 years old or above). They watched the different type of video in the randomly selected levels of display luminance on two separate occasions, and the key findings of this study are the following:

1. Between the videos, both resolution and frame rate were the same, and the levels of saturation was similar. The documentary had a higher levels of brightness, but the music video had higher color contrast and value. 2. Age-related decrease in both baseline and average pupil diameters were found, but there were no significant effects of both the levels of display luminance and the type of video on them. 3. Psychosensory reflex (PSR) and constriction were heavily outnumbered in the frequency of pupillary responses, and that of dilation was rare. 4. There were no considerable differences on the frequency of dilation between the comparison groups. However, while the music video had more frequencies of both PSR and constriction with a positive time trend in both first and second viewings, no time interactions with both responses were found in the linear mixed model (LMM) analysis. 5. Although the mean extent of dilation was not significantly affected by both display luminance and age groups, the documentary had a larger extent of dilation only at the first viewing and the type of video served to be a significant effector on it. In contrast, cumulative viewing ime was the only significant effector on the extent of PSR and constriction. 6. The mean velocity of dilation was slower in the adolescents and faster in the older adults. According to the results of LMM, the age group was the only primary effector on it. On the other hand, none of the comparison groups were significantly impacted by the velocity of PSR and constriction, and no outstanding fixed effects were found. 7. According to the results of multiple logistic regression between the video features and the frequency of each pupillary response, the type of video and the count of cyan together significantly affect all the responses in common.

It is concluded that the most sensitive factor responding to the prolonged dynamic visual stimuli is the frequency of pupillary responses. This study further suggests that the type of video and their features such as color composition can considerably influence the pupillary responses rather than the changes of display luminance.