Variation in assessments of suitability and number of contributors for DNA mixtures.

The interpretation of a DNA mixture (a sample that contains DNA from two or more people) depends on a laboratory/analyst's assessment of the suitability of the sample for comparison/analysis, and an assessment of the number of contributors (NoC) present in the sample. In this study, 134 participants from 67 forensic laboratories provided a total of 2272 assessments of 29 DNA mixtures (provided as electropherograms). The laboratories' responses were evaluated in terms of the variability of suitability assessments, and the accuracy and variability of NoC assessments.

Tracking the growth of visual evidence in fingerprint comparison tasks.

Fingerprint comparisons are extended in time due to the fine details (minutiae) that necessitate multiple eye fixations throughout the comparison. How is evidence accumulated across these multiple regions? The present work measures decisions at multiple points during a comparison to address how feature diagnosticity and image clarity play a role in evidence accumulation. We find that evidence is accumulated at a constant rate over time, with evidence for identification and exclusion accumulated at similar rates.

Characterizing Human Expertise Using Computational Metrics of Feature Diagnosticity in a Pattern Matching Task.

Forensic evidence often involves an evaluation of whether two impressions were made by the same source, such as whether a fingerprint from a crime scene has detail in agreement with an impression taken from a suspect. Human experts currently outperform computer-based comparison systems, but the strength of the evidence exemplified by the observed detail in agreement must be evaluated against the possibility that some other individual may have created the crime scene impression. Therefore, the strongest evidence comes from features in agreement that are also not shared with other impressions from other individuals.

The impact of fatigue on latent print examinations as revealed by behavioral and eye gaze testing.

Eye tracking and behavioral methods were used to assess the effects of fatigue on performance in latent print examiners. Eye gaze was measured both before and after a fatiguing exercise involving fine-grained examination decisions. The eye tracking tasks used similar images, often laterally reversed versions of previously viewed prints, which holds image detail constant while minimizing prior recognition.

ExpertEyes: open-source, high-definition eyetracking.

ExpertEyes is a low-cost, open-source package of hardware and software that is designed to provide portable high-definition eyetracking. The project involves several technological innovations, including portability, high-definition video recording, and multiplatform software support. It was designed for challenging recording environments, and all processing is done offline to allow for optimization of parameter estimation.