title: The Reliability of Pattern Classification in Bloodstain Pattern Analysis-PART 2: Bloodstain Patterns on Fabric Surfaces.
abstract: This study was designed to produce the first baseline measure of the reliability of bloodstain pattern classifications on fabric surfaces. Experienced bloodstain pattern analysts classified bloodstain patterns on pairs of trousers that represented three fabric substrates. Patterns also varied in type (impact, cast-off, expiration, satellite stains from dripped blood, and transfer) and extent. In addition, case summaries that accompanied each pattern contained contextual cues that either supported the correct answer (i.e., positive bias), were misleading toward an incorrect answer (i.e., negative bias), or contained no directional information (i.e., neutral). Overall, 23% percent of the resulting classifications were erroneous. The majority (51%) of errors resulted from analysts misclassifying satellite stains from dripped blood. Relative to the neutral information, the positive-bias information increased correct classifications and decreased erroneous classifications, and the negative-bias information decreased correct classifications and increased erroneous classifications. The implications of these findings for BPA are discussed.
authors.affiliation: Institute of Environmental Science and Research Limited (ESR), PO Box 29-181, Christchurch, 8540, New Zealand.
authors.forename: Michael C
authors.initials: MC
authors.lastname: Taylor
authors.affiliation: Minnesota Bureau of Criminal Apprehension (BCA), 1430 Maryland Ave East, St Paul, MN, 55106.
authors.forename: Terry L
authors.initials: TL
authors.lastname: Laber
authors.affiliation: Forensic Consultant & Associates, PO Box 814, Corning, NY, 14830.
authors.forename: Paul E
authors.initials: PE
authors.lastname: Kish
authors.affiliation: School of Psychology, University of Auckland, Private Bag 92019, Auckland, 1142, New Zealand.
authors.forename: Glynn
authors.initials: G
authors.lastname: Owens
authors.affiliation: Institute of Environmental Science and Research Limited (ESR), PO Box 29-181, Christchurch, 8540, New Zealand.
authors.forename: Nikola K P
authors.initials: NK
authors.lastname: Osborne
mesh_terms: D001801:Blood Stains; D003020:Clothing; D005554:Forensic Medicine; D015203:Reproducibility of Results; D013784:Textiles
keywords: bloodstain pattern analysis; cognitive science; contextual bias; fabric surfaces; forensic science; reliability