How Do We Recognize Faces?


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Power Point presentation used in 2012 at Penn State Behrend\'s Sigma Xi Undergraduate Research Conference.

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  • In today’s society, media especially television and movies popularize different aspects of crime and the justice system. The Usual Suspects.
  • Explain Foils. Foils are the filler pictures that are included in the photo array or the extra people in a line-up. They usually look very similar to the perpetrator.
  • First hypothesis: There is limited research on this phenomenon. Expanding on the research in this area. Second hypothesis: To confirm past findings (Macrae & Lewis confirmed this phenomenon using the Navon letters) – so what our hypothesis does is expands on their research to look into the use of additional tasks.Third hypothesis: Past research in this area is very divided so we were interested in seeing what we would find in our study.
  • Before we began our research we gained approval from the Institutional Review Board at Penn State University. We then recruited 65 total participants through a participation pool here at Behrend. As you can see it was pretty limited. We had mostly female participants and the large majority of our participants were caucasian.
  • Our Stimuli included an informed consent, a simple demographic survey, and 5 priming tasks. The control task was just a passage from a novel they were asked to read and then answer a few questions. For the additional 4 tasks we split them up into the two tasks we just reviewed with you which were the Hierarchical Figures and the Navon Letters. Participants either did the global or the local version of these tasks.
  • The easiest way for us to teach you about our procedure is to actually have you do what the participants did. The beginning of our procedure started with the informed consent and the demographic survey. We thought we would be nice today and let you all skip that part.
  • The next step we took was presenting the participants with a 10 person photo array – which is the one you see here. We gave them a brief summary of their recent criminal history. We then told the participants to take a good look at the pictures and they would see them later in the study.
  • They then participated in their randomly assigned task. So I’m going to ask all of you to do a small portion of what they did. (READ INSTRUCTIONS)
  • Once again, we’re going to take it easy on you and not make you go through the entire process – but our participants actually viewed 30 photos – 10 from the original array and 20 foils in that same process. -- If you were curious of how good your facial recognition accuracy is – both of the photos we showed you were NOT in the original 10.
  • I’m going to into more detail in just a moment, but here is a good visual depiction of the results we found. (Explain the axes, explain the different bars). As you can see very clearly here, especially in the Hierarchical Figures task – the Local priming group was significantly less accurate.
  • We looked at the differences between genders on accuracy and found no significant results – this just means that neither women or men are better at recognizing faces in this situation. Contrary to our hypothesis – global priming groups were not significantly more accurate. We also analyzed the relationship between accuracy and confidence and found no significance which tells us that how confident you are, or think you are, does not influence how accurate you really are in making an identification.
  • We ran a 2x3 between subjects ANOVA and we found that there was a main effect of priming group (global, local or control) on accuracy. To look further into this finding – we ran post hoc t-tests and found that the Local groups, for both tasks, were significantly less accurate than both the global and the control groups which confirms past research as well as shows that the phenomenon is not limited just to the Navon letters task.
  • Anytime you conduct research its always important to consider what implications your results may have – in our case we realized that there are so many factors influencing accuracy that in real-life situations the criminal justice system should really be finding ways to measure these variables as well as use them to make the process of eyewitness identification more accurate. Also, research has shown that juries look at eyewitness’s confidence as an indication of how accurate they are and they tend to place a very strong emphasis on this. Based on our results, which show that there is no relationship between these two variables it would be valuable to educate juries to help them understand that confidence does not necessarily mean accurate – which may in the end result in less false convictions.
  • There’s always room for improvement in research and we feel first of all that in future research a broader population should be used. (We attempted to measure our participants’ history of experienced or witnessed crimes however, so few of our participants had these experiences we were unable to use the data). As discussed before – there are many variables that may influence accuracy and we think its very important for future research to look at these variables as well as how they interact. And lastly, our study was limited in that we only used white males as our perpetrators so future research should look into using perpetrators of a difference or race or gender.
  • How Do We Recognize Faces?

    1. 1. Penn State BehrendHow Do We Recognize Faces? Kristan Russell | Erin McCreary
    2. 2. Our Study• Eyewitness Identifications• Lateralization Priming• The Study• Results
    3. 3. VariablesEstimator Variable System Variable Can not be controlled. Can and should be controlled.
    4. 4. Estimator Variables History Demographics Situation Confidence• Witnessed • Age • Presence of a • Confidence violence • Race weapon level the• Experienced • Gender • Trauma witness has violence • Stress in making an• Has viewed a identification • Of both the photo array witness and or line-up perpetrator
    5. 5. System Variables Procedure Foils Process Lateralization• Photo array • Similarity • Administration • Global• Line up • Quantity • Instructions • Local • Instructor • Priming• Sequential possibilities• Simultaneous • More recent
    6. 6. LateralizationGlobal Associated with the right hemisphere May enhance recognition accuracyLocal Associated with the left hemisphere May reduce recognition accuracy
    7. 7. Priming the BrainNavon Letters Global Identifying the larger letter “A” Local Identifying the smaller letters “S” Macrae & Lewis, 2002
    8. 8. Priming the BrainHierarchical Global Figures Identifying the direction the large square opens toward “right” Local Identifying the direction the small squares open towards “left”
    9. 9. HypothesesI. Global Lateralization tasks will enhance facial recognition accuracy.II. Local Lateralization tasks will impair facial recognition accuracy. I. (Macrae & Lewis, 2002)III. Overall confidence will significantly influence facial recognition accuracy.
    10. 10. Method• IRB – Research Approved• Participants: • Penn State Behrend • 18-24 years (M = 19) • 65 total • 49 female - 16 male • 85% Caucasian
    11. 11. Method• Stimuli: • Informed Consent • Demographic Survey • Priming Tasks • Control • Navon Letters Global • Navon Letters Local • Hierarchical Figures Global • Hierarchical Figures Local
    12. 12. The ProcedureInformed ConsentDemographic Survey
    13. 13. The Procedure Shown 10 Photos
    14. 14. The Procedure Randomly Assigned TaskYou will now be shown a large square made up of smaller squares. As the image appears please identify which direction the LARGE square is open towards. Answers can be: Up Down Left Right
    15. 15. The Procedure Randomly Assigned TaskUp Down Left Right
    16. 16. The Procedure Randomly Assigned TaskUp Down Left Right
    17. 17. The Procedure Randomly Assigned TaskUp Down Left Right
    18. 18. The Procedure Randomly Assigned TaskUp Down Left Right
    19. 19. The ProcedureWas this photo in the original photo array you viewed? YES NO
    20. 20. The Procedure How confident are you about your decision? 1 2 3 4 5 6 7Not at all Unsure ExtremelyConfident Confident
    21. 21. The ProcedureWas this photo in the original photo array you viewed? YES NO
    22. 22. The Procedure How confident are you about your decision? 1 2 3 4 5 6 7Not at all Unsure ExtremelyConfident Confident
    23. 23. The ProcedureDebriefedGiven Credit for Participation
    24. 24. Results 80 75 GlobalFacial Recognition 70 Accuracy (%) Control 65 60 Local 55 50 Navon Letters Hierarchical Figures Task Type and Priming Condition
    25. 25. 80 Results 70 Global 60 50 Control Navon Letters Hierarchical Local FiguresI. No significant effect of genderII. Global Priming Groups were not significantly more accurateIII.No significant relationship between accuracy and confidence
    26. 26. 80 Results 70 Global 60 50 Control Navon Letters Hierarchical Local FiguresI. Main effect of “Priming Group” on Accuracy. I. ANOVA Results I. F(2,59) = 6.45, p =.003II. Local Priming Groups for both tasks displayed less accurate compared to the control and global groups. I. Post Hoc T-Test Results: I. t(59) = 3.20, p = .002 [global vs local] II. t(59) = 3.24, p = .002 [control vs local]
    27. 27. Implications• Understand the factors that influence facial recognition accuracy – Use to our advantage• Take our knowledge into account when – Confidence – Jurors • Strong Emphasis  False Convictions
    28. 28. Future Research• Target population: • Broaden• Incorporating other variables • How they interact• Female perpetrators/foils • Only white males were used
    29. 29. AcknowledgmentsThis research was made possible through anUndergraduate Student Research Grant at PennState Erie, The Behrend College. Special thanksto our research advisor Dr. Dawn Blasko.
    30. 30. References• Hills, P., & Lewis, M. (2009). A spatial frequency account of the detriment that local processing of navon letters has on face recognition. Journal of Experimental Psychology, 35(5), 1427-1442.• Lawson, R. (2007). Local and global processing biases fail to influence face, object, and word recognition. Visual Cognition, 15(6), 710-740.• Macrae, C., & Lewis, H. (2002). Do i know you? processing orientation and face recognition. Psychological Science, 13(2), 194-196.• Perfect, T., Dennis, I., & Snell, A. (2007). The effects of local and global processing orientation on eyewitness identification performance. Memory, 15(7), 784-798