Objectives

Research on police body-worn cameras (BWCs) draws attention to the need for suspects to be aware of the devices for them to exert a deterrent, “civilising effect”, which can manifest as a reduction in the use of force in police-public interactions. This awareness can be manipulated audibly, visually, or both, yet no trials exist to test a visual stimulus that increases awareness of BWCs relative to BWCs without this function. In this field experiment, we test the effect of a visual warning of BWCs on use-of-force incidence.

Methods

A six-month cluster-randomised controlled trial involving spatiotemporal police units was conducted in Miami Beach, USA. The units were randomly assigned to the experimental group, which included officers who wore BWCs featuring multiple yellow stickers and “VIDEO & AUDIO” logo (used as a visual warning). Officers in the control group were equipped with BWCs without yellow stickers. Neither group was required to announce the presence of the BWCs, thus isolating the visual warning from the audial warning. Poisson regression models estimate the treatment effect, with confirmatory subgroup analyses based on the proactive versus reactive interactions.

Results

Statistically significant differences in the use of force by officers, but in the contrary direction: higher rate of use of force due to equipping officers with BWCs with yellow stickers relative to BWCs without the yellow stickers. Relative change analysis indicates that yellow stickers cause an increase in the rate of use of force in incidents involving proactive policing, with a less pronounced increase in reactive policing.

Conclusion

Without contextualising their use to citizens, raising awareness of the presence of BWCs can aggravate police-public encounters.

中文翻译：

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黄色贴纸背后：随身摄像头视觉警告对警察使用武力的矛盾效应

 目标

对警察随身摄像机（BWC）的研究引起人们的注意，嫌疑人需要了解这些设备，以便他们发挥威慑力，“文明效应”，这可以表现为警察与公众之间使用武力的减少互动。这种意识可以通过听觉、视觉或两者来操纵，但目前还没有试验来测试视觉刺激相对于不具有此功能的 BWC 来提高 BWC 的意识。在本次现场实验中，我们测试了生物武器视觉警告对使用武力发生率的影响。

 方法

在美国迈阿密海滩进行了一项为期六个月、涉及时空警察单位的整群随机对照试验。这些单位被随机分配到实验组，其中包括穿着带有多个黄色贴纸和“视频和音频”标志（用作视觉警告）的 BWC 的军官。对照组的警员配备了没有黄色贴纸的生物武器。两个团体都不需要宣布生物武器的存在，从而将视觉警告与声音警告分开。泊松回归模型通过基于主动与反应相互作用的验证性亚组分析来估计治疗效果。

 结果

军官使用武力方面存在统计上的显着差异，但方向相反：与没有黄色贴纸的 BWC 相比，配备有黄色贴纸的 BWC 的军官使用武力的比例更高。相对变化分析表明，黄色贴纸导致涉及主动警务的事件中使用武力的比率增加，而被动警务的增加则不太明显。

 结论

如果不将其使用与公民联系起来，提高人们对生物武器的认识可能会加剧警察与公众的接触。