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Monday, February 9, 2009

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
Jimmy Ryce Family Fights On
WJHG-TV, FL - Feb 5, 2009
“The murder weapon was found in his trailer with his fingerprint on it. Jimmy Ryce’s book bag was found in his trailer with his fingerprints on it. ...
Evolved transforms improve image compression
SPIE Newsroom, WA - Feb 3, 2009
This evolved transform also achieved 49.88% (3.00 dB) and 42.35% (2.39 dB) average MSE reduction when tested on 80 fingerprints and 18 digital photographs, ...
Ascension deputies nab 2 in burglaries
2TheAdvocate, LA - Feb 4, 2009
“West Baton Rouge got a latent fingerprint of a 16-year from a burglary. He was identified and arrested,” Bacala said. “A list of his known associates was ...
Ashland police arrest man in car-bomb case
Mail Tribune, OR - Jan 31, 2009
Police submitted a fingerprint found at the scene but no match was found until recently, when Campbell was arrested on another charge and his fingerprint ...
Science Found Wanting in Nation’s Crime Labs - Feb 5, 2009
“Forensic evidence is often the product of shoddy scientific practices that should be upgraded, a draft report found. ...

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    We are taking a break from publishing new entries on the Fingerprint Interest Group (FIG) page.  You may still submit your examples (anonymously if you desire) of unique distortion through Charlie Parker:  He will be preparing batches of FIGs for column continuation as they are submitted and formatted.  For discussion on existing FIGs, visit the forum FIG thread.

    Updated the Detail Archives

    Last week

    We looked at the NIJ sponsored NIST Expert Working Group on Human Factors in Latent Print Examination.

    This week

    we look at a report on a lecture given recently by Dr. Dror. 

    A Report on Dr. Itiel Dror's "Why Forensic Examinations are Inherently Biased, and What can be Done About it."

    by Cindy Rennie

    Al D’Silva


                On January 23, 2009, Dr. Itiel Dror, Senior Lecturer in the Department of Psychology at the University of Southampton (UK) gave a lecture at the University of Toronto entitled “Why forensic examinations are inherently biased, and what can be done about it.”

                Dr. Dror has spent many years researching the effect of psychological and contextual factors on decision-making in forensic examinations.  He has chosen to focus on the fingerprint field because it has been around for over a hundred years, it is well understood worldwide, and it carries a lot of weight in court. 

                The complete list of his experiments (and their findings) may be found at


                Dr. Dror began his lecture by listing what he calls “the ingredients of decision-making”:

    1.          Data – decisions are based on the information available at the time.

    2.          Parameters – decisions are affected by such factors as the number of alternatives available to the decision-maker, the complexity of the decision, and the amount of time available to them in which to make the decision.

    3.          The decision-maker themselves – decisions will be influenced by such factors as the age, gender, education, and level of experience of each decision-maker.


                One of the questions that his research asks is, “Is decision-making consistent?” or would a decision change if the circumstances were changed?


                 Dr. Dror believes that there are two sets of circumstances that affect a person’s decisions:  internal and external.  Internal circumstances include such things as each person’s point of view, level of expertise, education and values.

                External circumstances are the resources available to each person and the circumstances surrounding the decision (e.g., is there a “right” or “wrong” answer, and what are the consequences?)


                Dr. Dror’s experiments try to determine if the decision of a fingerprint examiner is based on the actual data and evidence available, or if it can be affected by context.

                He made reference to three of his studies of fingerprint examiners (all of which are available on the above-noted website) “When Emotions Get The Better Of Us: The Effect of Contextual Top-down Processing on Matching Fingerprints”; “Contextual Information Renders Experts Vulnerable to Making Erroneous Identifications”; and “Why Experts Make Errors”. (He mentioned that there were more studies on the website.)

                Here is an example of the kind of experiments that he is performing:


                The reader is most likely aware of the false identification to Brandon Mayfield that was made in the Madrid bombing case.  Dr. Dror chose five fingerprint examiners from a global list of volunteers, each of whom had approximately seventeen years’ experience in examining fingerprints, and none of whom had seen the Mayfield print.  The volunteers did not know when or how they would be tested. The fingerprints were presented to them in the normal course of their duties.

                Dr. Dror arranged to have a latent fingerprint retrieved from the files of each examiner - a latent fingerprint that had been identified by that examiner five years before. That same latent was presented to the examiner again along with the ‘known’ fingerprints of the suspect that they had identified, only this time the examiner was told that the latent and ‘known’ fingerprints were the ones involved in the false identification from the Madrid bombing case.

                The fingerprint experts were asked to decide whether there was sufficient information available in the pair of prints to make a definite and sound decision, and, if so, whether they found the two prints to be a ‘match’ or ‘non-match’.   They were instructed to ignore the context and background information, and focus only on the actual print in their evaluation and decision-making.

                Of the five examiners, only one stuck to his original decision and declared the two prints an ‘identification’.  The other four changed their decision – three said that the prints were a definite ‘non-ident.’, and one said that there was insufficient quality of detail to individualize.  (Remember, each examiner was looking at a set of prints that had come from their own caseload and that they had already declared as an identification in the past!).

                Dr. Dror states that this is an example of how the decisions of fingerprint examiners are vulnerable to irrelevant and misleading contextual influences. He says that it is impossible to ignore context.  Once an examiner is exposed to the context surrounding an examination, (such as the type of crime involved, or the fact that the investigators have other evidence that implicates this individual) they cannot put that context out of their mind – the examiner cannot ‘unlearn’ something that may affect their examination of the fingerprint.

                His new study examines the phenomenon of errors in fingerprint examinations. 

                He suggests that inconsistent identification decisions may be caused by ‘cognitive flaws’, which place limitations on the ability of the mind to conduct objective and independent processing and evaluation of information.

    The mind is not a camera, Dr. Dror explains. Each person’s mind perceives data differently.  Each person’s perception is influenced by such individual psychological issues as ‘attention span’, ‘confirmation bias’, ‘wishful thinking’, ‘escalation of commitment’ and ‘self-fulfilling prophesies’.    Dr. Dror is trying to determine if these factors lead to errors, and, if they do, are they ‘practitioner’ errors, or are they caused by a flaw in the process itself.

                Dr. Dror showed some examples of how the mind can be manipulated by outside factors.  He told the audience that he was going to show a video of two teams playing basketball.  Each team had four people on it. One team was dressed in white, one was dressed in black.  We were told to count the number of times that the members of the white team passed the ball without bouncing it first.

                 After the video was played, members of the audience had a wide variety of answers.  Some saw the white team pass the ball as many as seventeen times, others saw them pass the ball far fewer times.  What nobody saw was the six-foot man in a gorilla suit who strode into the middle of the picture, waved his arms around, and strode off! 

                We didn’t believe that there HAD been a six-foot gorilla in the video – until the video was played a second time.  There he was, big as life. We had been concentrating so much on watching the white players and the ball, that we did not see the gorilla.

                Dr. Dror explained that this is similar to an investigator (or fingerprint examiner) developing “tunnel vision” when working on a case.  If you concentrate on one area of the fingerprint, you run the risk of missing other information that you need to make an informed decision. 

                In another example, Dr. Dror put a phrase on the screen and asked the audience to count the number of times that the letter “f” appeared. Most of us counted five. It should have been eight. The word “of” appeared three times, and nobody had counted the “f”s in them.  Dr. Dror explained that the mind uses a kind of short-hand, where it recognizes and ignores some commonly seen words, such as “of”.

                He pointed out that these types of errors in perception and bias by context seem to have less influence on an expert when dealing with excellent prints of high quality.  The effects become more pronounced when dealing with poor quality prints that require more analysis.

                The short-term solution to the problems that Dr. Dror is studying lie in the selection and training of fingerprint examiners and in the procedures and protocols that govern each workplace.

                Dr. Dror also states that more research needs to be done into these topics. 

                Some of that research is being done by the National Academy of Sciences (NAS) (which is expected to publish the results of their latest research into the field of forensics shortly) and the National Institute of Studies in Technology (NIST).           


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    Have a GREAT week!