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Monday, November 3, 2008

The purpose of the Detail is to help keep you informed of the current state of affairs in the latent print community, to provide an avenue to circulate original fingerprint-related articles, and to announce important events as they happen in our field.
Breaking NEWz you can UzE...
by Kasey Wertheim
Lazar murderer could face death sentence
Monessen Valley Independent, PA - Oct 31, 2008
Todd Wharton, a forensic scientist with the state Bureau of Criminal Identification and Investigation, said Wednesday that he tested for fingerprints on the ...
Use fingerprint bureau, cops told
Express Buzz, India - Oct 29, 2008
BANGALORE: Fingerprints can become clinching evidence to nab culprits of crimes, ranging from chain-snatching to terrorist activities. ...
Iraq Court Convicts Killer of 2 Soldiers
Washington Post, United States - Oct 28, 2008
Ibrahim Karim Muhammed Salih al-Qaraghuli was found guilty and sentenced to death after expert testimony that his fingerprints matched photos of bloody ...
Woods receives 13-year sentence
Chillicothe Gazette, OH - Oct 31, 2008
During the trial, Andrew McCleland, a fingerprint expert from the Bureau of Criminal Identification and Investigation, testified that the fingerprints on ...

Recent CLPEX Posting Activity
Last Week's Board topics containing new posts
Moderated by Steve Everist and Charlie Parker

Public CLPEX Message Board
Moderated by Steve Everist

Great News For Megrahi (Lockerbie Bomber)
by Big Wullie on Wed Oct 15, 2008 12:39 pm 1 Replies 205 Views Last post by WRoughead
on Sat Nov 01, 2008 5:15 am

Tribunal for McKie print expert
1, 2, 3by charlton97 on Thu Sep 11, 2008 1:00 am 35 Replies 2198 Views Last post by WRoughead
on Sat Nov 01, 2008 4:22 am

Evidence Fabrication in South Africa
1 ... 19, 20, 21by Pat A. Wertheim on Fri Nov 30, 2007 12:48 pm 307 Replies 34734 Views Last post by Gerald Clough
on Fri Oct 31, 2008 12:33 pm

Microwavable Fingerprints?
by josher89 on Wed Oct 22, 2008 7:37 am 3 Replies 295 Views Last post by BC FIS
on Wed Oct 29, 2008 10:07 pm

RUVIS focusing issue
by MitchVFL on Wed Oct 22, 2008 10:11 am 3 Replies 183 Views Last post by AdamH
on Tue Oct 28, 2008 6:47 pm

The merits of putting Henry Faulds on a Pumpkin
1, 2 by Boyd Baumgartner on Tue Oct 21, 2008 11:17 am 20 Replies 607 Views Last post by Gerald Clough
on Tue Oct 28, 2008 2:40 pm

What's new in Print Challenges and Tech?
by L.J.Steele on Fri Aug 29, 2008 10:16 am 2 Replies 471 Views Last post by L.J.Steele
on Tue Oct 28, 2008 12:03 pm

Fingerprints rarely make case
by charlton97 on Mon Oct 27, 2008 5:59 pm 4 Replies 252 Views Last post by lpexaminer
on Tue Oct 28, 2008 10:17 am

The merits of photographing a latent at 1000 ppi
1, 2, 3 by antonroland on Fri Oct 17, 2008 8:27 am 35 Replies 620 Views Last post by antonroland
on Tue Oct 28, 2008 12:05 am

by charlton97 on Sat Oct 04, 2008 6:15 pm 12 Replies 551 Views Last post by rmcase
on Mon Oct 27, 2008 3:41 pm
IAI Conference Topics -
Louisville, Kentucky 2008:
Moderator: Steve Everist

No new posts

Documentation issues as they apply to latent prints
Moderator: Charles Parker

No new posts

Historical topics related to latent print examination
Moderator: Charles Parker

No new posts



Updated the Fingerprint Interest Group (FIG) page with FIG #68; a footprint comparison; submitted by Charlie Parker.  You can send your example of unique distortion to Charlie Parker:  For discussion, visit the forum FIG thread.

Updated the forum Keeping Examiners Prepared for Testimony (KEPT) thread with KEPT #42; No prints found - Why weren't any fingerprints found?; submitted by Michelle Triplett.  You can send your questions on courtroom topics to Michelle Triplett:

Updated the Detail Archives

Last week

we looked at an interesting thread on the forum.

This week

we look at the introduction of an excellent general psychology article on Confirmation Bias.

Confirmation Bias: A Ubiquitous Phenomenon in Many Guises
[introduction only reproduced for the Weekly Detail]

by Raymond S. Nickerson, Tufts University

Review of General Psychology
1998, Vol. 2, No. 2, 175-220

Copyright 1998 by the Educational Publishing Foundation

Confirmation bias, as the term is typically used in the psychological literature, connotes the seeking or interpreting of evidence in ways that are partial to existing beliefs, expectations, or a hypothesis in hand. The author reviews evidence of such a bias in a variety of guises and gives examples of its operation in several practical contexts. Possible explanations are considered, and the question of its utility or disutility is discussed.

When men wish to construct or support a theory, how they torture facts into their service! (Mackay, 1852/1932, p. 552)

Confirmation bias is perhaps the best known and most widely accepted notion of inferential error to come out of the literature on human reasoning. (Evans, 1989, p. 41)

If one were to attempt to identify a single problematic aspect of human reasoning that deserves attention above all others, the confirmation bias would have to be among the candidates for consideration. Many have written about this bias, and it appears to be sufficiently strong and pervasive that one is led to wonder whether the bias, by itself, might account for a significant fraction of the disputes, altercations, and misunderstandings that occur among individuals, groups, and nations.

Confirmation bias has been used in the psychological literature to refer to a variety of phenomena. Here I take the term to represent a
generic concept that subsumes several more specific ideas that connote the inappropriate bolstering of hypotheses or beliefs whose truth
is in question.

Deliberate Versus Spontaneous Case Building

There is an obvious difference between impartially evaluating evidence in order to come to an unbiased conclusion and building a case to justify a conclusion already drawn. In the first instance one seeks evidence on all sides of a question, evaluates it as objectively as one can, and draws the conclusion that the evidence, in the aggregate, seems to dictate. In the second, one selectively gathers, or gives undue weight to, evidence that supports one's position while neglecting to gather, or discounting, evidence that would tell against it.

There is a perhaps less obvious, but also important, difference between building a case consciously and deliberately and engaging in
case-building without being aware of doing so. The first type of case-building is illustrated by what attorneys and debaters do. An attorney's job is to make a case for one or the other side of a legal dispute. The prosecutor tries to marshal evidence to support the contention that a crime has been committed; the defense attorney tries
to present evidence that will support the presumption that the defendant is innocent. Neither is committed to an unbiased weighing of all the evidence at hand, but each is motivated to confirm a particular position. Debaters also would be expected to give primary attention to arguments that support the positions they are defending; they might present counterarguments, but would do so only for the purpose of pointing out their weaknesses.

As the term is used in this article and, I believe, generally by psychologists, confirmation bias connotes a less explicit, less consciously one-sided case-building process. It refers usually to unwitting selectivity in the acquisition and use of evidence. The line
between deliberate selectivity in the use of evidence and unwitting molding of facts to fit hypotheses or beliefs is a difficult one to draw in practice, but the distinction is meaningful conceptually, and confirmation bias has more to do with the latter than with the former. The one may seek evidence of that fact or give undue weight to such evidence. But in such cases, the hypothesis in question is someone else's belief. For the individual who seeks to disconfirm such
a hypothesis, a confirmation bias would be a bias to confirm the individual's own belief, assumption that people can and do engage in
case-building unwittingly, without intending to treat evidence in a biased way or even being aware of doing so, is fundamental to the

The question of what constitutes confirmation of a hypothesis has been a controversial matter among philosophers and logicians for a long time (Salmon, 1973). The controversy is exemplified by Hempel's (1945) famous argument that the observation of a white shoe is confirmatory for the hypothesis "All ravens are black," which can equally well be expressed in contrapositive form as "All nonblack things are nonravens." Goodman's (1966) claim that evidence that something is green is equally good evidence that it is "grue"—grue being defined
as green before a specified future date and blue thereafter—also provides an example. A large literature has grown up around these and similar puzzles and paradoxes. Here this controversy is largely ignored. It is sufficiently clear for the purposes of this discussion that, as used in everyday language, confirmation connotes evidence
that is perceived to support—to increase the credibility of—a hypothesis.

I also make a distinction between what might be called motivated and unmotivated forms of confirmation bias. People may treat evidence in
a biased way when they are motivated by the desire to defend beliefs that they wish to maintain. (As already noted, this is not to suggest intentional mistreatment of evidence; one may be selective in seeking or interpreting evidence that pertains to a belief without being
deliberately so, or even necessarily being aware of the selectivity.) But people also may proceed in a biased fashion even in the testing of
hypotheses or claims in which they have no material stake or obvious personal interest. The former case is easier to understand in commonsense terms than the latter because one can appreciate the tendency to treat evidence selectively when a valued belief is at risk. But it is less apparent why people should be partial in their uses of evidence when they are indifferent to the answer to a question in hand. An adequate account of the confirmation bias must encompass
both cases because the existence of each is well documented.

There are, of course, instances of one wishing to disconfirm a particular hypothesis. If, for example, one believes a hypothesis to be untrue, one may seek evidence of that fact or give undue weight to such evidence. But in such cases, the hypothesis in question is someone else's belief. For the individual who seeks to disconfirm such
a hypothesis, a confirmation bias would be a bias to confirm the individual's own belief, namely that the hypothesis in question is false.

A Long-Recognized Phenomenon

Motivated confirmation bias has long been believed by philosophers to be an important determinant of thought and behavior. Francis Bacon (1620/1939) had this to say about it, for example:

The human understanding when it has once adopted an
opinion (either as being the received opinion or as
being agreeable to itself) draws all things else to
support and agree with it. And though there be a greater
number and weight of instances to be found on the
other side, yet these it either neglects and despises, or
else by some distinction sets aside and rejects; in order
that by this great and pernicious predetermination the
authority of its former conclusions may remain
inviolate.. . . And such is the way of all superstitions,
whether in astrology, dreams, omens, divine judgments,
or the like; wherein men, having a delight in
such vanities, mark the events where they are fulfilled,
but where they fail, although this happened much
oftener, neglect and pass them by. (p. 36)

Bacon noted that philosophy and the sciences do not escape this tendency.

The idea that people are prone to treat evidence in biased ways if the issue in question matters to them is an old one among psychologists

If we have nothing personally at stake in a dispute
between people who are strangers to us, we are
remarkably intelligent about weighing the evidence and
in reaching a rational conclusion. We can be convinced
in favor of either of the fighting parties on the basis of
good evidence. But let the fight be our own, or let our
own friends, relatives, fraternity brothers, be parties to
the fight, and we lose our ability to see any other side of
the issue than our own. .. . The more urgent the
impulse, or the closer it comes to the maintenance of
our own selves, the more difficult it becomes to be
rational and intelligent. (Thurstone, 1924, p. 101)

The data that I consider in what follows do not challenge either the notion that people generally like to avoid personally disquieting
information or the belief that the strength of a bias in the interpretation of evidence increases with the degree to which the evidence relates directly to a dispute in which one has a personal stake. They are difficult to reconcile, however, with the view that evidence is treated in a totally unbiased way if only one has no personal interest in that to which it pertains.

The following discussion of this widely recognized bias is organized in four major sections. In the first, I review experimental evidence of the operation of a confirmation bias. In the second, I provide examples of the bias at work in practical situations. The third section notes possible theoretical explanations of the bias that various researchers have proposed. The fourth addresses the question of the effects of the confirmation bias and whether it serves any
useful purposes.

Read the remainder of the 45-page article at:

KEPT - Keeping Examiners Prepared for Testimony - #42
by Michele Triplett, King County Sheriff's Office


Disclaimer:  The intent of this is to provide thought provoking discussion.  No claims of accuracy exist. 


Question – No Prints Found:

Why weren’t any fingerprints found?


Possible Answers:

a)      It could be because the item was wiped down.  This would clean away any latent prints that may be on an item.

b)      Usually it’s because the person who touched the item was a non-secretor, a person who doesn’t sweat and leave latent fingerprints.

c)      It’s frequently because the person who handled the item was wearing gloves.

d)     It could be due to a variety of reasons.  One latent print recovery condition is whether or not the item is conducive to accepting latent fingerprints.  This has to do with the material and the texture of the item being touched.  Another factor is in regards to the person who touched the item, whether or not there was a transferable substance on their hands (or on the object) or how they handled the item.  A 3rd factor is how the item was handled, packaged, or processed after it was initially touched.  These factors could destroy any latent fingerprints that were on the object. Another possibility is that the object wasn’t handled.



Most latent print examiners are very familiar with latent recovery condition. Even so, there are many people who could use a review of this information.  It’s also important to remember that “A lack of evidence isn’t evidence itself”, which means that we shouldn’t imply anything from an absence of latent prints.  There are times when we can make an inference about whether or not the item was touched but examiners need to be very careful about arriving at this type of conclusion, making sure they have additional information to support such a conclusion.

a)  The wiping down of an object is a possibility but experts shouldn’t assume an item was wiped down merely from a lack of latent prints.

b) The idea that non-secretors don’t leave latent prints is another false assumption.  A person doesn’t need to sweat to leave a latent print; there just need to be a transferable substance on their hands or on the item.

c) Examiners should rarely make a judgment on whether or not a person wore gloves when touching an item.  Some people may not realize that it’s actually possible for a person to leave latent prints while wearing gloves.  Anyone testifying to latent print evidence should fully understand all of the latent print recovery conditions.

d) This is a very complete answer and can be articulated in a variety of ways.




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Until next Monday morning, don't work too hard or too little.

Have a GREAT week!