The influence of exposure time on facial composite construction for own-race and cross-race conditions

Objectives:

(1) to examine whether exposure time will significantly influence the creation of facial composite when using EigenFit and (2) to determine the relation between confidence and accuracy among eyewitness during creation and matching procedures.

Design:

2 (exposure time: 12s x 45s) x 2 (line-up type: Target Present x Target Absent) x 15 (target faces) Methods: 30 participants were shown the target face – 15 for an exposure time of 12 seconds and 15 for 45 seconds. After a 30-minute delay, they were asked to create facial composite using EigenFit. Thirty further participants took part in the matching procedures. All photos of faces used in matching procedures were 5x5 centimetres with white background. Random line-ups were built by using 15 target pictures used in the first part and 70 distracter photos. In each trial there were 30 line-ups with 15 culprit-absent line-ups and 15 with culprit present.

Analysis:

ANOVAs were performed with post-matching level of confidence ratings as the dependent measure, correlations analysis were done to show the accuracy and confidence level relation, Chi-Square was conducted to determine difference among the frequency of hits and false identifications in TP and TA line-ups and correct/mistaken answers, Signal Detection Theory (SDT) allowed separating sensitivity from response bias.

Conclusions:

It was also found that longer exposure significantly increases eyewitness’s confidence level. Participants working under the longer exposure condition created faces that were better identified in the matching procedure that followed.