評論
打印
Science and technology
科學技術
Forensic science
司法科學
Ignorance is bliss
無知即是福
Forensic scientists know too much about the cases they investigate
法醫科學家對他們調查的案子知道得太多
AS ALL fans of crime fiction know, DNA is the gold standard of forensic science. Or is it?
所有的罪案小說迷都知道，DNA是司法科學的黃金標準。它到底是么？
Itiel Dror, a cognitive psychologist at University College, London, thinks this doctrine of infallibility needs to be questioned.
一位倫敦的大學認知心理學專家Itiel Dror認為這個說法的正確性有待考驗。
His problem is not with the technology itself, but with the way it is deployed.
他的問題不是針對技術本身而是它進行的方式。
For he has gathered evidence that DNA examiners' interpretations of their results are, at least in complex cases, open to subjectivity and bias.
因為他已經搜集了證據證明DNA鑒定者對他們結果的解釋至少在復雜的案子里易受主觀性和偏差的影響。
When America's National Academy of Sciences produced a report on the state of forensic science in 2009,
當美國國家科學院在2009年發表了一片關于司法科學現狀的報告時，
it criticised many of the methods then in use.
它批判了很多當時正在應用的鑒定方式。
Citing earlier research by Dr Dror, the report's authors stated,
引用這篇報道的作者Dror博士早前做的研究，
for example, that fingerprint examiners' claims of zero error rates were scientifically implausible.
例如，指紋鑒定者宣稱的零誤差在科學上是不合理的。
DNA, however, was spared their criticism. Now Dr Dror and Greg Hampikian,
然而DNA省去了他們的批判。
a forensic biologist at Boise State University in Idaho, have published a study in Science & Justice that suggests all is not shipshape in the domain of the double helix either.
現在，Dror博士和博伊西的愛達荷州立大學的法醫學生物學家Greg Hampikian在科學與正義上發表了一篇研究，表明所有的東西都不是井然有序的，在雙螺旋線的領域里也不是。
Dr Dror's and Dr Hampikian's experiment presented data from a real case to 17 DNA examiners working in an accredited government laboratory in North America.
博士Dror和Dr Hampikian博士的實驗提供一個真實案例的數據給17個在一家受認可的北美政府實驗室里工作的DNA鑒定員。
The case involved a gang rape in the state of Georgia, in which one of the rapists testified against three other suspects in exchange for a lighter sentence,
這起案件涉及到一宗喬治亞州的輪奸案，其中一名強奸犯為了讓自己獲得輕判做了不利于其它三名嫌疑者的證言，
as part of a plea bargain.
作為認罪辯訴協議的一部分。
All three denied involvement, but the two DNA examiners in the original case both found that they could not exclude one of the three from having been involved, based on an analysis of swabs taken from the victim.
其他三名嫌疑人全部否認參與強奸，但是根據從受害者處提取的藥簽分析，原案中有兩位DNA鑒定師都發現他們無法排除三名中的其中一名參與了強奸。
As is almost always true in forensic-science laboratories, these examiners knew what the case was about.
由于在司法科學實驗室里總是什么都是對的，這些鑒定師們知道這個案子到底是怎么回事了。
And their findings were crucial to the outcome because in Georgia, as in many other states, a plea bargain cannot be accepted without corroborating evidence.
而且他們的手指對于出來的結果是至關重要的，因為在喬治亞，同時也在很多其它州，認罪辯訴如果沒有確實的證據是無法被接受的。
However, of the 17 examiners Dr Dror and Dr Hampikian approached—who, unlike the original two,
然而，在Dror博士和Hampikian接觸的17個鑒定師中—他們不像開始兩位鑒定師那樣，
knew nothing about the context of the crime,
對犯罪內容一無所知，
only one thought that the same suspect could not be excluded.
有一位認為一樣的嫌疑不能被排除。
Twelve others excluded him, and four abstained.
另外十二位把他排除了，而四位棄權。
Though they cannot prove it, Dr Dror and Dr Hampikian suspect the difference in contextual information given to the examiners was the cause of the different results.
盡管他們無法證明，Dror博士和Hampikian博士懷疑鑒定師得到的上下文信息的區別是引起這些不同結果的原因。
The original pair may have subliminally interpreted ambiguous information in a way helpful to the prosecution, even though they did not consciously realise what they were doing.
開始的兩個人也許已經在下意識里以某種有益于控方的方式破譯了模棱兩可的信息，即使他們沒有清楚地意識到當時他們在做什么。
And DNA data are ambiguous more often than is generally realised.
而且DNA數據往往比普遍了解的要模棱兩可。
Dr Dror thinks that in about 25% of cases, tiny samples or the mixing of material from more than one person can lead to such ambiguity.
Dror博士認為在大約25%的案子里，小樣本或者從不止一人身上取來的混合物質可能導致這樣的二義性。
Moreover, such is DNA's reputation that, when faced with claims that the molecule puts a defendant in a place where a crime has been committed,
此外，DNA的好名聲就是這樣，當面臨宣稱用DNA分子證明被告所犯的罪的時候，
that defendant will often agree to a plea-bargain he might otherwise not have accepted.
被告通常會同意認罪辯訴，否則他也許不會接受。
This one example does not prove the existence of a systematic problem.
這個例子沒有證明系統性問題的存在。
But it does point to a sloppy approach to science.
但是它確實指出了一個科學上草率的方法。
According to Norah Rudin, a forensic-DNA consultant in Mountain View, California, forensic scientists are beginning to accept that cognitive bias exists,
根據一位加利福尼亞州芒廷維尤的法庭DNA顧問Norah Rudin，法庭科學家正在開始接受那種認知性偏差的存在，
but there is still a lot of resistance to the idea, because examiners take the criticism personally and feel they are being accused of doing bad science.
但仍然有很多阻力，因為鑒定師個人會接受批評，覺得自己被譴責說自然科學學得差。
According to Dr Rudin, the attitude that cognitive bias can somehow be willed away, by education, training or good intentions, is still pervasive.
根據Rudin博士，認知偏差可以通過某種方式意識性去除的態度是普遍的，比如通過教育、訓練或好意的方式。
Medical researchers, by contrast, take great care to make drug trials blind,
相比之下，醫學研究者非常注意使藥物試驗不透明，
so that neither the patient nor the administering doctor knows who is receiving the drug being tested, and who is getting a control drug or placebo.
所以病人和用藥的醫生都不知道接受藥物測試的是誰，和控制藥物和安慰劑的是誰。
When someone's freedom—and, in an American context, possibly his life, as well—is at stake,
在美國環境中，當某人的自由和他的生命也危在旦夕的時候，
it surely behoves forensic-science laboratories to take precautions that are equally strong.
法醫科學實驗室應當采取相當的強預防措施。
