Face Matching Under Time Pressure and Task Demands

Face Matching Under Time Pressure and Task Demands Michael D. Lee (mdlee@uci.edu) Department of Cognitive Sciences, University of California, Irvine Irvine, CA, 92697-5100 Robyn L. Vast (robyn.vast@psychology.adelaide.edu.au) School of Psychology, University of Adelaide South Australia, 5005, AUSTRALIA Marcus A. Butavicius (marcus.butavicius@dsto.defence.gov.au) Intelligence Surveillance and Reconnaissance Division, Defence Science and Technology Organisation PO Box 1500, Edinburgh SA 5111 AUSTRALIA Abstract Understanding how people recognize and match faces is important in many real-world situations, including policing, military, security and retail environments. We investigate the effects of time pressure and addi- tional task demands on face matching performance. In a 2x2 factorial design—varying whether there was high or low time pressure, and whether or not an ad- ditional task had to be completed—participants were asked to judge whether each of a series of face image pairs were of the same person. Large individual differ- ences were observed. Recall was higher than precision, and performance worsened under high time pressure with the additional task. Learning effects within con- ditions were observed, and response times were gener- ally independent of the decisions made. Some impli- cations of these findings for applied environments are discussed. Introduction Face matching is the process of verfiying the equiva- lence of two or more people on the basis of their fa- cial characteristics. It involves visually perceiving a face, and matching this face to a known individual or identification image (Lewis & Edmonds 2003). Under- standing how people match faces is an important issue in cognitive science for both theoretical and practical reasons. On the theoretical front, it involves studying core cognitive representational and decision-making processes with complicated natural stimuli. On the practical front, understanding how people match faces has application in areas such as policing, the military, security, eyewitness testimony, social interactions and biometric identification. Previous research has considered the processes used, and conditions under which, humans can remember, match and recognize both familiar and unfamiliar faces (e.g., Baudouin, Gilibert, Sansone & Tiberghein 2000; Nagayama 1999; Shapiro & Penrod 1986). Through focusing primarily on the effects of disguises, and changes in appearance, race, and gender, past research has highlighted that humans are often not very skilled at recognizing unfamiliar faces (Burton, Miller, Bruce, Hancock & Henderson 2001; Luckman, Allinson, Ellis & Flude 1995; Shapiro & Penrod 1986). Other research suggests that image quality (Bruce et al. 1999; Hen- derson, Bruce & Burton 2001; Inui & Miyamoto 1984; Liu, Seetzen, Buton & Chaurdhuri 2003), illumination and exposure time (DiNardo & Rainey 1991; Laugh- ery, Alexander & Lane 1971), image colour (Bruce et al. 1999; Yip & Sinha 2002), moving as opposed to static facial images (Henderson et al. 2001; Kemp, Towell & Pike 1997; Knight & Johnston 1997; Lander & Bruce 2003) and distance and perspective (Hager & Ekman 1979; Harrigan & Taing 1997) can also influ- ence face recognition. In operational environments, face matching tasks are often performed repetitively over long time periods, under strict time limits and processing guidelines, and in conjunction with other related tasks. For example, face matching tasks are often performed in banks, air- ports, retail outlets, for access to buildings or licensed venues, and when obtaining official documents or pro- ducing proof of age or identity. It is an interesting empirical question, therefore, how time pressure and the need to perform additional tasks might affect face matching performance. The present research examines these issues. Experiment Method Participants Thirty-one first year psychology stu- dents from the University of Adelaide and 17 members of the general community were involved in the study. The students received course credit for their participa- tion. Of the 48 participants, there were 33 females and 15 males, ranging in age from 17 to 58 years (M=23.27, SD=9.63). Design A within-subjects design was used. Partici- pants completed 400 trials, 100 under each condition (high time pressure with additional task, low time pres- sure with additional task, high time pressure with no additional task, low time pressure with no additional task). Each condition included 90 ‘same face’ pairs showing two images of the same person and ten (ran- domly distributed) ‘different faces’ pairs showing dif- ferent people. Every participant viewed the same pairs