不仅如此，现在医生做手术时也不再穿白色大褂，而穿着绿大褂或蓝大褂。如果外科医生长时间盯着患者鲜红的内脏和血液，一旦他抬头扫过白大褂，便会在白底上投射出很多“鬼怪”一样的绿色残影。这种现象在心理学中称为视觉负后像（negative afterimage），也即某种颜色长时间刺激后再接受白光，眼中便会出现它的补色[10]。而红色的补色正好是蓝绿色，因此换上绿大褂或蓝大褂之后，便能在一定程度上“中和”医生因长时间观察红色而产生的“鬼影“，也就能避免干扰医生的注意力。

色轮，位置相对的颜色即为互补色，与红色对应的版块是绿色。图片来源：sessions.edu

白大褂的新争议

经过一百余年的发展，白大褂已经成为全体医护人员的精神象征。然而，近几年却有一些专业人士对白大褂提出了反对意见，他们认为白大褂已渐渐沦为一种新型细菌培养皿——虽然没有直接证据能够证明白大褂会在医院内造成交叉感染[11]，但有不少研究发现白大褂的袖筒和口袋确实会滋养大量细菌[12-13]，而且这些细菌是可以将白大褂作为媒介进而感染患者[14-15]。

为此，英国于2008年最先出台了一部规范医生着装的守则，其中禁止医生在工作场合穿着包括白大褂在内的长袖上衣[16]。2009年美国医学会（American Medical Association）部分会员也提议彻底禁止白大褂，但学会最后以“还需要更多研究”为由否决了该提议[17]。目前，相关的争论仍在医学界内继续。

有趣的是，白大褂在19世纪末登上历史舞台是因为它能有效隔绝细菌，而一百多年后它遭到质疑却是因为在隔绝细菌上做得不够好。在前一个阶段，白大褂顺应了现代医疗的发展潮流，而在后一个阶段它被一部分人视作现代医疗发展的羁绊。人们对白大褂态度的变化，从本质上说是人类认识进一步深化、更为接近事物原貌的结果，这么看，白大褂的发展也像是现代医疗事业发展的缩影。

参考文献：

Glick, S. M. (2003). White coat ceremonies--another commentary. Journal of Medical Ethics, 29(6), 367-368.

Jones, V. A. (1999). The white coat: why not follow suit?. Jama the Journal of the American Medical Association, 281(5), 478.

Howe, E. D., & Boeckl, C. M. (2003). Images of plague and pestilence: Iconography and iconology. Renaissance Quarterly, 56(1), 205.

Lister, J. (2010). On the antiseptic principle in the practice of surgery. Clinical Orthopaedics & Related Research, 468(8), 2012-2016.

Lister, J. (2015). Remarks on the antiseptic system of treatment in surgery. Br Med J, 2(409), 53-56.

Lister, J. (1867). On the effects of the antiseptic system of treatment upon the salubrity of a surgical hospital. Lancet, 95(2418), 4-6.

Hochberg, M. S. (2007). The doctor's white coat-An historical perspective. Virtual Mentor Vm, 9(4), 310.

Millard, C., & Michael, P. (2011). The destiny of the republic: a tale of madness, medicine and the murder of a president. Doubleday.

Glen, S. K., Elliott, H. L., Curzio, J. L., Lees, K. R., & Reid, J. L. (1996). White-coat hypertension as a cause of cardiovascular dysfunction. Lancet, 348(9028), 654-657.

Burden, M., Cervantes, L., Weed, D., Keniston, A., Price, C. S., & Albert, R. K. (2011). Newly cleaned physician uniforms and infrequently washed white coats have similar rates of bacterial contamination after an 8-hour workday: a randomized controlled trial. Journal of Hospital Medicine, 6(4), 177-182.

Varghese, D., & Patel, H. (1999). Hand washing, stethoscopes and white coats are sources of nosocomial infection. Bmj, 319(7208), 519.

Loh, W., Ng, V. V., & Holton, J. (2000). Bacterial flora on the white coats of medical students. Journal of Hospital Infection, 45(1), 65-68.

Mackintosh, C. A., & Hoffman, P. N. (1984). An extended model for transfer of micro-organisms via the hands: differences between organisms and the effect of alcohol disinfection. Epidemiology & Infection, 92(3), 345-355.

Scott, E., & Bloomfield, S. F. (1990). The survival and transfer of microbial contamination via cloths, hands and utensils. Journal of Applied Bacteriology, 68(3), 271.

Murphy, Clare. "Death of the doctor's white coat". BBC News. BBC. Retrieved 5 December 2014.

Yao, Laura. "AMA: White Coats Need More Study". The Wall Street Journal. The Wall Street Journal. Retrieved 5 December 2014.