how do we recognize faces?

How Do We Recognize Faces?

Penn State Behrend

Kristan Russell Erin McCreary|

Our Study

• Eyewitness Identifications• Lateralization Priming• The Study• Results

VariablesEstimator Variable System

Variable Can not be controlled. Can and should

be controlled.

Estimator Variables

History

• Witnessed violence

• Experienced violence

• Has viewed a photo array or line-up

Demographics

• Age• Race• Gender

• Of both the witness and perpetrator

Situation

• Presence of a weapon

• Trauma• Stress

Confidence

• Confidence level the witness has in making an identification

System Variables

Procedure

• Photo array• Line up

• Sequential• Simultaneous

Foils

• Similarity• Quantity

Process

• Administration• Instructions• Instructor

Lateralization

• Global• Local• Priming

possibilities

• More recent

LateralizationGlobal

Associated with the right hemisphereMay enhance recognition accuracy

LocalAssociated with the left hemisphereMay reduce recognition accuracy

global

local

Priming the Brain

GlobalIdentifying the larger letter“A”

LocalIdentifying the smaller letters“S”

Navon Letters

Macrae & Lewis, 2002

Priming the BrainGlobal

Identifying the direction the large square opens toward“right”

LocalIdentifying the direction the small squares open towards“left”

Hierarchical Figures

Hypotheses

I. 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.

Method

• IRB – Research Approved

• Participants:• Penn State Behrend• 18-24 years (M = 19)• 65 total

• 49 female - 16 male• 85% Caucasian

Method• Stimuli:

• Informed Consent• Demographic Survey• Priming Tasks

• Control• Navon Letters Global• Navon Letters Local• Hierarchical Figures Global• Hierarchical Figures Local

The Procedure

Informed Consent

Demographic Survey

The Procedure Shown 10 Photos

The ProcedureRandomly Assigned Task

You 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

The ProcedureRandomly Assigned Task

Up Down Left Right

The ProcedureRandomly Assigned Task

Up Down Left Right

The ProcedureRandomly Assigned Task

Up Down Left Right

The ProcedureRandomly Assigned Task

Up Down Left Right

The Procedure

Was this photo in the original photo array you viewed?

YES NO

The Procedure

How confident are you about your decision?

1 2 3 4 5 6 7

Not at all UnsureExtremely

ConfidentConfident

The Procedure

Was this photo in the original photo array you viewed?

YES NO

The Procedure

How confident are you about your decision?

1 2 3 4 5 6 7

Not at all UnsureExtremely

ConfidentConfident

The Procedure

Debriefed

Given Credit for Participation

Results

Faci

al

Reco

gn

itio

n

Acc

ura

cy (

%)

Task Type and Priming Condition

Navon Letters Hierarchical Figures50

55

60

65

70

75

80

Global

Control

Local

Results

I. No significant effect of gender

II.Global Priming Groups were not significantly more accurate

III.No significant relationship between accuracy and confidence

Navon Letters Hierarchical Figures

50

60

70

80

GlobalControlLocal

Results

I. Main effect of “Priming Group” on Accuracy.I. ANOVA Results

I. F(2,59) = 6.45, p =.003

II. 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]

Navon Letters Hierarchical Figures

50

60

70

80

GlobalControlLocal

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

Future Research• Target population:

• Broaden

• Incorporating other variables• How they interact

• Female perpetrators/foils• Only white males were used

Acknowledgments

This research was made possible through an Undergraduate Student Research Grant at Penn State Erie, The Behrend College. Special thanks to our research advisor Dr. Dawn Blasko.

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