Defining Habituation using Hand Geometry
                    Eric P. Kukula'                                              ...
Userintroduced to hiQmebics stemorntfirstte.                                                         During week 7, partic...
of LEDs) to facilitate correct hand placement in the hand                           10o                                   ...
TABLE I.                             ANALYSIS OF NUMBER OF ATTEMPTS, GROUP 1                                              ...
TABLE III.            MEANS AND STANDARD DEVIATIONS, WEEK 1 AND WEEK 7                            thirty), and the ranges ...
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(2007) Defining Habituation Using Hand Geometry

  1. 1. Defining Habituation using Hand Geometry Eric P. Kukula' Stephen J Elliott, Ph.D.2 Industrial Technology, Purdue University Industrial Technology, Purdue University West Lafayette, Indiana USA West Lafayette, Indiana USA Bryan P. Gresock3 Nathan W. Dunning4 Industrial Technology, Purdue University Computer Technology, Purdue University West Lafayette, Indiana USA West Lafayette, Indiana USA Abstract-The word "habituation" has many meanings within the device or any other biometric to the general population, biometric community. Most people define the concept of training of the device's users is very important. habituation as "continued use of a biometric device." When a user is habituated, he or she is capable of providing repeatable Each biometric modality has specific interaction issues that samples to the biometric sensor, and the performance scores of need to be resolved through training. For hand geometry the biometric sensor, relative to that user, have stabilized. This readers, training must emphasize hand placement because hand paper establishes a model of the processes of habituation and placement is a key component to successful use. Since hand provides score data from hand geometry to show how this geometry is dependent on orientation of a user's hand, most concept works with actual data. We illustrate a four-step process hand readers have pins to facilitate the process of orienting the of a user's interaction with the device and describe how the data user's hand for correct alignment. Training must address how seems to prove that an individual becomes fully habituated after users should interact with the alignment pins. If the user does repeated use of the device. The type and amount of user training, not perform hand placement correctly, interaction will be and number of interaction attempts are shown to have an impact problematic and a higher than normal matching score will on the biometric sensor's performance scores. result. A higher matched score could lead to false rejections (FRRs) [2]. With any technology-based system, training is Keywords- biometrics, hand geometry, habituation, human- essential for the ongoing successful use and integration of the technology. Understanding how users' habituation and acclimation relates to the successful use of hand readers will I. INTRODUCTION establish the appropriate training period that customers of a How an individual interacts with a biometric device so as to particular type of biometric systems can anticipate. make consistent, repeatable presentations is an important topic of discussion within the biometrics community. In this paper, ii. HABITUATION AND ACCLIMATION we propose a novel process to define habituation and provide data on how quickly individuals in different circumstances can The definition of habituation varies, depending on context. fully habituate. For this experiment, we use a hand geometry [4] notes two recurring characteristics for acclimation and device. habituation. First, acclimation is the process in which a user of a biometric system adapts his or her techniques to achieve a Hand geometry has been utilized commercially for more proper match of his or her biometric template. Second, than three decades [1]. The first hand geometry readers were habituation may be partial or full (complete). Partial used in government facilities to provide high-level security habituation is the period of time during which no new access to settings such as nuclear power plants [2]. Hand adaptation techniques are used to achieve a successful match to geometry readers are becoming increasingly ubiquitous; today, the biometric template. Full habituation occurs when a user they can be found in public applications ranging from hotels, matches his or her biometric template using subconscious college dormitories, and manufacturing plants to parking lots; techniques. Becoming fully habituated to a biometric system is they support access control, as well as time and attendance a four-step process, as shown in Figure 1. In the first step, a tracking [3]. user is introduced to the equipment for the first time. Note that Hand geometry measures the size and shape of the human the four "steps" are not discrete, but rather are continuous; hand [3]. When an individual places his or her hand on a overlaps between the steps will occur. reflective platen and makes contact with the alignment pin, a picture of the hand is taken. When deploying a hand geometry 1-4244-1300-1/07/$25.OO 2007 IEEE 242 Authorized licensed use limited to: Purdue University. Downloaded on February 27,2010 at 14:23:00 EST from IEEE Xplore. Restrictions apply.
  2. 2. Userintroduced to hiQmebics stemorntfirstte. During week 7, participants in group 3 enrolled in the reader and were required to provide three scores under thirty. cclimation: User adapts his techniques to tytaErnxnachanrnn rna Toldwhato. Group 4 enrolled in the hand geometryieader drru ngweek E achievepropermatchofbiometrictemplate. r t Self Teaching - 2 of the experiment; participants in this group revisited every ChlangtingoneDas Changing rAy to s [llif behavior Changingtosurvive[s] Self techniquestousethe week and made one verification attempt, mimicking A d ti tW a What arethe differentw Teaching device? A device? l typical a access control application. There were no scoring constraints for group 4 during weeks 2, 4, or 6. _s__t___I_Ch_r_____ks Partial Habituation: Nomatch adaptation nechrique you wantto repeat.T P q p p gr p | The rotocol required all articipants new of biometric of Pickthetechnique inoupsto all fbru-itmpwohansdt detalused Nbriasbc ative learnglevel tat albsh daiy sfeub-c onscience to be used template echnique to achieve proper template.Selection - l perform three consecutive verification attempts with scores characte6fstics: resulting in a reduced numbera oferrors and number encel Reducedresponsvenessto ovne under thirty during week 7 (the experiment's final week), as experence [3] ofaftemptstoaftainalevelofpetformance. Reducedl resptbnsiVeness to given a I L D ~~~~~~~~~~~~~~~~~~~~Learn the selected u* this was a strict threshold level. The four groupsconducted HabituatiprcessWorksits Repeated technique. verification attempts until each participant successfully theconSCicus[5] L ak of sponse[2] Full Habituation: User matches biometric aet chieved three scores under thirty to establish whether there P 'Nop out habituatoour assbdiativb learning [8] template by subcoscious techiques. was a statistically significant dIfference among groups With observations[8] n ndvou prebocupiewth nsignificarit Fuhe rdciono repniveest dbel a ove thets Pefr expenence. Users require minimal concentration and no/minimal errors producinga tighter dissibutionof withoutonnsciPerForm S ubwihthlous t cought. use weeks. thought thetaskl7 subjected to different levels of training over the previous six scores, minutiae, etc... Figure 1. Conceptual model of habituation/acclimation for biometrics A. Experimental Setup Testing involved two commercially available hand geometry readers (see Figure 3) situated on a desk at an III. METHODOLOGY elevation of twenty-nine inches from the floor. Participants The motivation for this study is to more fully understand performed the test while seated in a chair to exclude the the appropriate level of training required to achieve repeatable potential influence of extraneous factors such as variations of performance. The hypothesis was to examine the hand the participants' heights. geometry scores from four groups of participants who interacted with the device in different scenarios. Figure 2 shows the experimental design ofthe four groups. Group 1 enrolled during the first week of the seven-week study and performed verification attempts during each week of data collection until they achieved three consecutive scores under the threshold of thirty. Group 2 simulated the recommendations from the InterNational Committee for Information Technology Standards (INCITS) M1.5 draft standard (1602D-5): members of group 2 utilized six-week intervals between revisits. In this Figure 3. Schlage Recognition Systems Handkey IIR scenario, during week 1 and week 7, group 2 participants were required to provide three consecutive scores under the threshold of thirty. B. Enrollment Enrollment is the process of collecting a biometric sample Week 1 Week 2 Week 3 Week 4 Week 5 Week 6 Week 7 in this case, hand geometry from a person. The data from 8/21 8/28 914 9111 9/18 9/25 1012 the sample is processed and stored in a database as a template for subsequent usage to validate an individual's identity. Prior Group I Enol to this study, study participants had no experience with a hand er X ~~~~~~~~~~3 3 3 ~ ~ ~ ~ 3- 3 under30. under30. unde 30 30. 3 geometry reader, and were neither habituated nor acclimated. Group 2 Enroll 3 ~~~~~~~~~Four groups were created and each group was enrolled at different periods over the course of the study. When seated, participants were provided with instructions Enol on how to use the device and a brief demonstration on the Group 3 proper technique for hand placement A test administrator was present to ensure each test participant followed the test protocol Enrollfor enrollment. Upon completion in the participant's unique of the demonstration and Group 4 1 A At1 3 Group training, the administrator entered code and the participant placed his or her dominant hand onto Figure 2. Experimental design of the four groups the platen of the hand geometry reader, applied pressure to the pins, and kept the hand in position until the test administrator Group 3 served as our control group; they did not interact instructed the participant to to remove the hand from the with the hand geometry reader until week 7 (the final week). reader. Participants were provided with visual cues (in the form 1-4244-1300-1/07/$25.00 2007 IEEE 243 Authorized licensed use limited to: Purdue University. Downloaded on February 27,2010 at 14:23:00 EST from IEEE Xplore. Restrictions apply.
  3. 3. of LEDs) to facilitate correct hand placement in the hand 10o Week I Group I Attempts vs. Score reader. When the LEDs on the hand reader are extinguished, 90- then the participant has achieved proper pin / finger placement. 80- Enrollment consisted of three hand placements to create a 70Q unique template for each test participant. In some cases, the device may have required additional hand placements if the 40 ' . first three did not satisfy the enrollment criteria. 3- = C. Verification Verification is the process of matching a claimed identity to 4 C. 7 9 I 12 13 14 a biometric characteristic or sample. The hand geometry unit used in this study functions as a one-to-one (verification) -Wek 2 Group I - Attempts vs. Score system. During each verification attempt, the test participant entered the unique four-digit number provided during enrollment and, aided by visual cues from the hand geometry system, placed his or her hand on the platen around the guide pins, as had been instructed and demonstrated during the 40 enrollment stage. 3l IV. RESULTS { M Central to this paper is the definition of habituation and 1 2 3 4 5 6 7 a 910 1 13 l examination of the amount of interaction required to achieve Week 4 Group I - Attempts vs. Score that status. The study endeavors to answer to research question, 90 "What is the appropriate level of training and interaction Ho required to achieve repeatable performance?" The statistical 7- analysis investigated two variables across the groups: number 60 of attempts and the match score output from the hand geometry device. 30 Before further analysis, tests for violation of the assumption - of normality were performed. The results of the normality tests showed the match score data was normally distributed, but the 4................ 14 attempt data was not. Since each group had a defined level of interaction, the number of attempts were similar within each of 1X=Week roupi - Attempts vs Score the groups, causing the distribution of attempts to be 901 multimodal and thus non-normal. 81 0 701 601 A. Group I Results 50 Group 1 enrolled during week 1 of the study and performed 41 verification attempts during each week of data collection until* each member of the group receiving three consecutive scores under the threshold of thirty. The model assumed that the ID process would fully habituate the group's participants. 4 6 7 9 1o I 12 3 4 Examining group 1 scores and attempts by the participants over seven weeks yielded a drop in the scores, but the change was 0 Week 7 Groupi I Attempts vs Sore0 not statistically significant. The visual representation of these 90 results (see Figure 4) shows the process of acclimation and habituation occurring over the seven-week period. The university's academic calendar precluded collection of data during weeks 3 and 5. It is interesting to note that, after week 3, 4t participants regressed in performance, whereas after the week 5 30| break, the participants varied less as a group. Examination of 20 . the week 7 chart shows that most participants are habituated to - the device; they required minimal attempts to perform three consecutive scores under thethresholdofthirtv. The data also3 consecutive under the threshold of thirty. The data also 4 5 6 7 8 9 to I 1. 4S i 14 reveals decreases as the mean number of attempts by week Figure 4. Group 1 time series plot of attempts vs. scores reveal partial decreased, as well as the median, standard deviation, and habituation variance (see Table 1). 1-4244-1300-1/07/$25.00 2007 IEEE 244 Authorized licensed use limited to: Purdue University. Downloaded on February 27,2010 at 14:23:00 EST from IEEE Xplore. Restrictions apply.
  4. 4. TABLE I. ANALYSIS OF NUMBER OF ATTEMPTS, GROUP 1 attempt in weeks 2, 4, and 6 no real analyses could be performed. However at week 7, this group had the lowest range 1 Wcc1 M2n 5.267 M4 4 n 3Std D10iati9n 3.24 Varianc 10.495 and mean score, as shown in Figure 6. 2 4.8 5 1.612 2.6 E. All Groups Combined 4 44.667 4 2.41 5.81 6 4.133 4.133 3 3 1.552 1.552 2.41 2.41.' In order to consider the groups together, a one-way analysis 3933 1 438 2 067 Iof variance (ANOVA) was performed to examine the average 7 3.933 3 1.438 2.067 score of the four groups during week 7 (see Figure 6). This ANOVA revealed significant differences between the four B. Group 2 Results groups: F (3,253) = 4.58 and p < 0.004 (see Table 2). The results reveal that participants in groups 1 and 4 have the Group 2 enrolled in week 1 ofthe study and then completed lowest mean scores and the least amount of variation in scores three verification scores under thirty. After six weeks, the participants returned and again attempted to complete three in week 7. Interpreting the results, participants in groups 1 and verifications with scores under thirty. The mean number of 4 progressed towards full habituation, which is illustrated in attempts was 4.71 for week 1 and 5.21 for week 7 Figure 6, the plot of the match scores. There was no statistically significant difference between the 100- attempts on week 1 and week 7. The graphical summary for all participants is shown in Figure 5. It is apparent that the process go of habituation does not occur and participants perform no better in week 7 than they did in weekl. 60 60- 1to WeeIk I Group 2 - Attempts vs. == Stoe 90- < 40- '70) 60- 20 ~ 30 S, V A 7 0 I 2 3 4 IWIf- ,._, .- roup 0- IFigure 6. Week 7 match scores, by group 3 2 3 4 5 6 7 9 9 10 II I2 iS3 14 I. Wee1 7 Group 2 _ Atte mptsJ vs. Score tk TABLE II. MEANS AND STANDARD DEVIATIONS, ANOVA OF WEEK 7 9',90*1 # A SCORES ACROSS GROUPS So 01 Group N (Attcmpts) t IISD 601 ., N *I fS:R 1 ~~~~~~1 ~ _____53_____ _ 1 18.66 1 13.22 40i 2 73 27.38 17.96 m. v ,kkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkrkkkkkkkki 'kkkkkkI8 .8 %.6 if2 4 44 18.3 10.5 1 2 3 4 5 6 7 9 t 1t ' 12 13 X4 The second analysis examined the difference in Figure 5. Group 2 time series plot of attempts vs. scores reveal no performance of groups 1 and 2 during week 1 (the first week of acclimation or habituation the study) and week 7 (the last week of the study). A one-way ANOVA analyzed the average score of groups 1 and 2 during C. Group 3 Results week 1, which revealed no statistically significant difference between the two groups: F (1, 133) = 0.10 and p=O.747, which Group 3 enrolled and verified three times in the last week would be expected, since both groups received the same of the study. There should have been no difference between treatment. However, when this analysis was repeated on the group 3 scores in week 7 and those of the other groups during data gathered six weeks later, the results were quite different. their respective enrollment weeks. As expected, there was no The ANOVA revealed a statistically significant difference in statistically significant difference between the groups. the mean scores between groups 1 and 2: F (1, 124)= 8.97 and Nonetheless, it is interesting to note that the range of matching p=0.003. Table 3 lists the means and standard deviations for scores for group 3 was greater than the other groups. week 1 and week 7 analyses. Figures 7 and 8 show the graphical representation of these analyses. Refer to Figures 4 D. Group 4 Results and 5 to assess the relationship between attempts and scores of This group mimicked the access control environment of one the two groups in weeks 1 and 7. attempt each week. As these participants only conducted 1 1-4244-1300-1/07/$25.00 2007 IEEE 245 Authorized licensed use limited to: Purdue University. Downloaded on February 27,2010 at 14:23:00 EST from IEEE Xplore. Restrictions apply.
  5. 5. TABLE III. MEANS AND STANDARD DEVIATIONS, WEEK 1 AND WEEK 7 thirty), and the ranges of these groups were smaller than those SCORES FOR GROUPS 1 AND 2 of groups 2 and 3. Therefore, when considering habituation of a hand geometry reader, it is important to recognize that the type Week Group N (Attcmpts) ll SD and number of training attempts and interaction will affect the 1 1 69 21.07 13.47 score. This factor is crucial to practitioners implementing biometric solutions in their organizations, as the cost for 2 1F 66 21 l.85 2 14.43 training and instruction is high. 7 1 53 18.66 13.22 2 73 27.38 17.96 VI. FUTURE WORK While this paper provides a conceptual framework for defining habituation and provides data that shows the process 70- of habituation, there are other factors that can have an effect on habituation. The authors believe training might affect whether, 60- . when, and how long it takes to achieve habituation. Therefore, 50; *instead ofbe interestingnumber of interactions,experiment that, it would varying the to conduct a similar varies the type t 40 0 t *= =and amount of training a participant receives before enrollment =X *s==** 0% to determine whether the type of training, (i.e., no training; i30- visual instruction; oral instruction; and a combination of oral and visual instruction with and hands-on experience) changes 20. _ - - the progress toward habituation and acclimation. 10 4 3 . ' = VII. g ,, REFERENCES 0- [1.] A. Jain and N. Duta, "Deformable matching of hand shapes for G 2 verification," presented at the 1999 International user Conference on Image Processing, Kobe, Japan, October 24- Figure 7. Plot of match score for groups 1 and 2 for week 1 28, 1999. [2.] Zunkel, D., Hand Geometry Based Verification, in Biometrics: 100- Personal Identification in a Networked Society, S. Pankanti, 100 Editor. 1999, Kluwer Academic Publishers: Norwell. p. 87- 101. so- [3.] E. Kukula and S. Elliott, "Implementation of hand geometry at Purdue University's recreational center: An analysis of user e60 * perspectives and system performance," presented at the 39th Annual International Carnahan Conference on Security = . * =. Technology (ICCST), Las Palmas de Gran Canaria, Spain, 4 4Q 4e:0 == * .October 12, 2005. * * = , i [4.] M. Thieme, D. Setlak, E. Kukula, S. Pankanti, K. Gregory, and N. Sickler, (February 17, 2005), "Ad hoc Report: Effects of -20 user habituation and acclimation in the context of biometric performance testing," (No. M1/05-0139), Washington: ~~~~~~~~~ ~~~~~~~~INCITS. Available: 0- http:HwwwJncitsorgtc home/r dlhtm/docs/m 10501 39pdf. Grou'p [5.] M. P. Haines, "Habituation and social norms," The Report on Social Norms. 2005, 4(7). Available: Figure 8. Plot of match score for groups 1 and 2 for week 7 [6.] Merriam- Webster Online, "Habituation," from http://www.m- V. CONCLUSION [7.] V7.] WordNet 2.1, "Habituation," retrieved September 4, 2006, from This paper outlines a model for determining the levels of habituation and provides data on various methods of interacting [8.] The American Heritage® Dictionary of the English Language with a hand geometry device, with the objective of (2004, 4th ed), "Habituation," from [9.] The demonstrating the level of trainingi required to use this parntuardic particular devicetoiitS best outc .I It .iS apparent,' based on to n best outcome. - . e ased on . appairent, American Heritage® Stedman's Medical Dictionary (2004), ''~~~~~Acclimation"' "Aciato, from fro http://medical- htp/eicl the data that repeated use of the device yields some increase in the performance success of participants .relative to the device.* . . . .10.] ~~~~~Wikipedia.ic"Acclimation," [10.] (2006a), . retrieved September 18, The groups whose participants interacted with the device over a 2006, from longer period of time (groups 1 and 4) had lower scores, [11.] Wikipedia (2006b), "Habituation," retrieved September 4, 2006, although fewer interactions (attempts to achieve scores under from 1-4244-1300-1/07/$25.OO 2007 IEEE 246 Authorized licensed use limited to: Purdue University. Downloaded on February 27,2010 at 14:23:00 EST from IEEE Xplore. Restrictions apply.