Breaking NEWz you can UzE...
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
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BANGALORE: Fingerprints can become clinching evidence to nab culprits of crimes, ranging from chain-snatching to terrorist activities. ...
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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
containing new posts
Moderated by Steve Everist and Charlie Parker
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
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
For discussion, visit the CLPEX.com forum FIG thread.
Updated the forum Keeping Examiners Prepared for
thread with KEPT #42; No prints found - Why weren't any fingerprints found?;
by Michelle Triplett. You can send your
questions on courtroom topics to Michelle Triplett:
Updated the Detail Archives
we looked at an interesting thread on the CLPEX.com
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
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
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
Read the remainder of the 45-page article at:
- Keeping Examiners Prepared for Testimony - #42
by Michele Triplett, King County
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?
It could be because the item was wiped down.
This would clean away any latent prints that may be on an item.
Usually it’s because the person who touched the item was a
non-secretor, a person who doesn’t sweat and leave latent fingerprints.
It’s frequently because the person who handled the item was
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
d) This is a very complete answer and can be
articulated in a variety of ways.
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