A study looking at how the conclusions of forensic anthropologists may be influenced by extraneous information highlights the importance of protecting all scientists from potentially biasing information.
Forensic anthropologists determine the gender, national origin, and age of a person at the time of death. In some cases this determination must be based solely on skeletal remains. A recent study introduced extraneous information to the scientists when remains were submitted for scientific analysis and found that background information can bias a scientist’s conclusions and result in mis-identifications across the board.
In this study, three test groups were assembled to analyze the remains of a nineteenth century female skeleton with strikingly neutral, or “ambiguous,” features which could allow a conclusion of either sex. An ambiguous environment is one that creates the greatest potential for cognitive bias. Cognitive bias occurs when contextual information influences a person’s thought process and may lead to inaccurate judgment. In this case, scientists relied on information that was submitted with the evidence, causing them to make conclusions validating or complementing the extraneous information.
Two of the three groups were given DNA profiles in addition to skeletal remains. The first group’s DNA profile indicated the skeletal remains belonged to a Caucasian male between 25-30 years of age. The second group was given a DNA profile indicating the same skeleton was an Asian female between 50-55 years of age. The third group, the control group, was given no supplementary information. Each scientist, ranging from master’s degree students to practicing PhDs in anthropology, was given up to an hour to examine the remains and make conclusions. In the first group, 72% concluded the remains were male and 100% of examiners in the second group concluded the remains were female. In the control group 31% of examiners concluded the remains were male and 69% concluded female.
Regarding ancestry, 100% of group one (who were told the skeleton was Caucasian) and 100% of the control group (who were given no extra information) decided that the skeleton was Caucasian. In group two, where the scientists were told the skeleton was of Asian ancestry, 50% concluded the skeleton was of Asian descent and 50% concluded Caucasian. The study attributes the bias in both group one and the control group to cognitive bias and bias generated from ancestrally-common characteristics described in anthropological textbooks.
This study showed that age at time of death is the least affected category by cognitive bias. Anthropologists in each group reached conclusions about age independent of the supplied information.
This study shows how biasing contextual information can affect a scientist’s ability to be impartial. The accuracy and credibility of a scientist’s conclusions depends upon blinding the scientist to any information that can be consciously or unconsciously biasing. Attorneys may be interested in reading similar studies that have looked at how contextual information can bias examiners in the fields of blood spatter interpretation, fingerprint comparison, and DNA interpretation.