Valid facial cues to cooperation and trust: male facial width and trustworthiness.
|Valid facial cues to cooperation and trust: male facial width and trustworthiness. Stirrat,M|
|Title||Valid facial cues to cooperation and trust: male facial width and trustworthiness.|
|Authors||M Stirrat,DI Perrett|
|Publication Year||Mar 2010|
- 1 Abstract
- 2 Acronyms
- 3 Received 5/22/09; Revision accepted 8/7/09
- 4 Experiment 1: Male Trust and Reciprocation
- 5 Method
- 6 Results and discussion
- 7 Experiment 2: Perceived Trustworthiness
- 8 Method
- 9 Results and discussion
- 10 Experiment 3: Manipulation of Facial Images
- 11 Method
- 12 rep
- 13 Results and discussion
- 14 General Discussion
- 15 Tables
Decisions about whom to trust are biased by stable facial traits such as attractiveness, similarity to kin, and perceived trustworthiness. Research addressing the validity of facial trustworthiness or its basis in facial features is scarce, and the results have been inconsistent. We measured male trustworthiness operationally in trust games in which participants had options to collaborate for mutual financial gain or to exploit for greater personal gain. We also measured facial (bizygomatic) width (scaled for face height) because this is a sexually dimorphic, testosterone-linked trait predictive of male aggression. We found that men with greater facial width were more likely to exploit the trust of others and that other players were less likely to trust male counterparts with wide rather than narrow faces (independent of their attractiveness). Moreover, manipulating this facial-width ratio with computer graphics controlled attributions of trustworthiness, particularly for subordinate female evaluators.
|a => asked to|
|p > .20, p rep < .72 => (p > .20, p rep < .72), attractiveness (p = .07, p rep = .85), and facial-width ratio|
Received 5/22/09; Revision accepted 8/7/09
- face most source information, strangers.
- People can judge extroversion conscientiousness face levels chance (Penton-Voak, Pound, Little, Perrett, 2006).
- Research shown consensus perceptions facial trustworthiness (Zebrowitz, Voinescu, Collins, 1996), evidence validity judgments .
- Decisions to trust biased by stable facial traits attractiveness (Wilson & Eckel, 2006), similarity kin (DeBruine, 2002), trustworthiness (van't Sanfey, 2008).
- Some evidence shown people can judge a face someone ease deception (Berry, 1990; Bond, Berry, Omar, 1994); , others failed replicate this result (Masip Garrido, 2001) found either no correlation a negative correlation between judgments faces measures of trustworthiness (Hassin Trope, 2000; Zebrowitz al., 1996).
- expressions support evaluation noncooperation (Verplaetse, Vanneste, Braeckman, 2007) perceptions of trustworthiness relate expression (Oosterhof Todorov, 2009), little evidence exists showing biases based stable facial traits .
- Some research shown evidence validity judgments facial trustworthiness.
- faces trusted (Wilson & Eckel, 2006), male attractiveness
- (Takahashi, Yamagishi, Tanida, Kiyonari, Kanazawa, 2006) male symmetry (Zaatari & Trivers, 2007) predict less behavior economic games.
- facts terms sexual selection male dominance sexual dimorphism.
- relationships found male dominance, reactive aggression, variation a .
- Weston, Friday, Lio (2007) shown adults skull bizygomatic width corrected height.
- Variation male bone growth, growth, testosterone effects adolescence (Verdonck, Gaethofs, Carels, de Zegher, 1999).
- Carré and McCormick (2008) found variation facialwidth ratio predicted male participants other-rated dominance, reactive aggression lab, number ice hockey penalties.
- Carré and McCormick (2008) measured reactive aggression amount times a participant counterparts points a point-subtraction task.
- a measure a behavior altruistic punishment ( Fehr Gachter, 2002,
- ability based greater physical robustness dominance, reduce consequences interactions.
- status lead increased behavior reduced cooperation, similar by Zaatari and Triv-ers (2007).
- male variation facial-width ratio relates (a) cooperation in economic games (Experiment 1) ( ) trust judgments others (Experiments 2 3).
Experiment 1: Male Trust and Reciprocation
- total 143 White heterosexual University of St Andrews students participated (107 women, 36 men; mean age = 21.6 years, SD = 2.3 years, range = 18--35 years).
- different set 50 male and 50 Uni-versity St Andrews students (ages 18--25) photo-graphed pose 1 year before the experiment.
- Procedure trust game.
- Participants were informed that they would a series economic games money.
- gave consent, completed questionnaires, photographed.
- Participants were informed that outcomes games depend decisions behavior their counterparts.
- a choice version trust game (Berg, Dickhaut, McCabe, 1995; Huck, Ruchala, Tyran, 2006).
- Participants 49 games with male counterpart images 50 games with counterpart images.
- game, only information counterparts a image exclude hair clothing.
- Images split by sex two blocks games, order of presentation, block, images allocated participants either first second move.
- first mover chose between game--each player would receive 3 GBP ( 5.00)-- money counterpart.
- first mover trusted second, 2 ( 3.00) added, second mover either split money --each player would receive 4 ( 6.50)-- -- first mover would receive 2 ( 3.00), second mover would receive 6 ( 10.00).
- first move measure trust, second a measure of trustworthiness.
- Before games started, participants completed examples games payoffs outcomes.
- Participants reported counterparts recognized.
- trials omitted analysis.
- Participants exchange rate 1 100 ; earnings ranged 3 6 ( 5.00 10.00).
- Following methodology Carré and McCormick (2008), measured calculated ratio
- bizygomatic width face height participants photographs ( - 1).
- Participants play summarized proportion of decisions to trust proportion of decisions male images, images, all images.
- Spearman correlations calculated test relationships between participant facial-width ratio, trust, reciprocation.
Results and discussion
- Women, on average, trusted 45% 69% their counterparts.
- facial-width ratios female participants not correlate any trust game behavior (see Table 1).
- Male participants trusted 51% counterparts 72%, on average.
- facial-width ratios male participants showed no relation to trust decisions relate decisions to reciprocate (r s = --.40, n= 36, p= .015, p rep = .94; see Table 1).
- Male participants with higher facial-width ratios (wide faces) more exploit their counterparts trust than male participants with lower width
- (slim faces).
- Experiment 2, tested participants judgments trustworthiness variation male facial-width ratio.
Experiment 2: Perceived Trustworthiness
- total 62 White heterosexual University of St Andrews students participated (45 women, 17 men; mean age = 20.32 years, SD = 1.5 years, range = 18--25 years).
- presented images 67 White male University of St Andrews students (mean age = 20.8 years, SD = 2.7 years) attended university least 2 years before the participant cohort participants.
- These images rated attractiveness by 41 raters (24 women, 17 men; mean age = 21 years).
- Measures facialwidth ratio same as in Experiment 1 ( - 1).
- Trust games conducted as in Experiment 1 except participants assigned only first mover 67 games, male counterpart images presented order.
- calculated proportion participants trusted image.
- tested normality Kolmogorov-Smirnoff test.
- Trust (p > .20, p rep < .72), attractiveness (p = .07, p rep = .85), and facial-width ratio (p > .20, p rep < .72) distributed.
Results and discussion
- Images trusted by 46% (SD = 21%) participants on average.
- Decisions across participants (Cronbach α= .88).
- least squares regression analysis revealed that facial-width ratio predicted 16% variation trust decisions, β(66) = --3.96, R 2 = .157, p= .001, p rep = .99 ( - 2), wider faces trusted less.
- Image attractiveness correlated facial-width ratio (R = --.32, p< .01, p rep = .96) correlated trust decisions (R = .54, p< .0005, p rep = .99).
- Including image attractiveness a regression analysis revealed that attractiveness (~30%) facial-width ratio (~6%) variance trust decisions (Model R 2 = .351, p< .0005, p rep = .99; image attractiveness β= 0.465, p< .0005, p rep = .99; facial-width ratio β= --2.48, p= .023, p rep = .92.
- male facial-width ratio a cue male trustworthiness predicts trust male faces.
- not ratio driving trust judgments; excluded attractiveness a correlate analysis, that facial-width ratio correlates other cues.
- Experiment 3, examined effect manipulating facial-width ratio images decisions to trust other dimensions .
Experiment 3: Manipulation of Facial Images
- experiment included 285 online participants ethnicities (208 women, 77 men; mean age = 23.2 years, SD = 4.4 years, range = 18--35 years; 84% reporting White ethnicity).
- Twelve male images were manipulated alter facialwidth ratio; base images a composite three photographs mask identity use on-line experiments.
- images were manipulated shape (Rowland Perrett, 1995), increase decrease facialwidth ratio ( - 3).
- control artifacts manipulation process, images three different transforms calculated
- three different male image sets (n = 19, n= 36, n= 49; age range = 18--27 years) collected different times different cohorts students.
- All images 179 feature points.
- data set, highest lowest facial-width-ratio images (measured Experiments 1 and 2) selected, high low groups, average location feature points calculated.
- Images were manipulated by base images by 25% difference between average locations feature points low facial-width-ratio group and high facial-width-ratio group manipulations high facial-width transforms manipulations low facial-width transforms.
- 72 transformed images stimuli 12 base images two directions three different transforms.
- distribution facial-width ratio 72 images not differ facial-width ratio distribution image sets.
- Participants were informed that they would pairs of images asked to (a) each pair looked more trustworthy ( ) complete a short questionnaire.
- Participants gave consent.
- Participants split three groups and presented all 12 identity pairs.
- Presentation images each participant all 12 identities all three transforms; each participant group different identities matched different transforms.
- order of presentation 12 pairs of images randomized, higher lower facial-width-ratio image of each pair side screen.
- Participants given a choice image each pair looked more trustworthy.
- After experiment, completed a short questionnaire including attractiveness self-rated dominance ( , Gaulin, Verdolini, 2006) 7-point Likert-type scales.
- each participant, proportion trust high facial-width-ratio low facial-width-ratio manipulations
- found no significant difference decisions between three participant groups mean responses, Kruskal-Wallis H(2) = .11, p= .95, p rep = .12, nor find significant differences between participant mean responses three different manipulations, Friedman N(2) = 285, p= .22, p rep = .70.
- found no significant difference mean responses between male and female participants (U = 8,004.5, p= .99, p rep = .04.
- data across participant sex groups and tested a effect image manipulation by chi-square.
- Men women differed age (U = 6,315.5, p= .005, p rep = .88) dominance (U = 6,316, p= .039, p = .89) split test correlations between trustworthiness judgments and other variables.
Results and discussion
- participants, 120 showed no bias more chose the images with higher facial-width ratio as more trustworthy, 165 chose the images with lower facial-width ratio as more trustworthy.
- Participants significantly more choose the images with lower facial-width ratio as trustworthy, χ 2 (1, N= 285) = 7.11, p< .005, p rep = .97.
- No significant correlations were found between male average choices age, self-rated dominance, self-rated attractiveness (ps > .61, p rep < .43).
- a significant correlation was found between average choice image with low facial-width ratio and self-rated dominance (r s = --.17, p= .018, p rep = .93).
- no relationship between trustworthiness judgments and self-rated attractiveness (p = .98, p rep = .07) age (p = .47, p rep = .52).
- Male facial-width ratio drives perceptions of trustworthiness, less female evaluators.
- This result validated interpretation Experiments 1 and 2.
- females more males and more attention attributes line interaction outcome dependency (Erber Fiske, 1984).
- Experiment 1 showed ratio ( ) width height predicts male reciprocation behavior trust games wider faced males more exploit trust than slimmer faced males.
- Experiment 2, participants less to trust male counterparts rather than slim faces ( attractiveness).
- Experiment 3, manipulating face width computer graphics controlled attributions trustworthiness, female evaluators.
- results demonstrate width-to-height ratio a cue trustworthiness.
- less cue originated maintained.
- overgeneralization emotion perception, similarity individual expression expressions anger happiness biases
- impressions traits (Montepare Dobish, 2003; Oosterhof Todorov, 2008), influence decisions to trust.
- This theory results , instance, (a) men a pose a higher facial-width ratio angrier than men with a lower facial-width ratio ( ) men with angry-looking faces greater exploitation trust.
- hypotheses remain tested.
- Weston et al. (2007) suggested sexual dimorphism facial-width ratio has resulted from sexual selection operating mate choice (p. 4).
- accordance this theory, women favor men with wide faces reproduction.
- Explanations male attractiveness (Takahashi al., 2006) symmetry (Zaatari & Trivers, 2007) correlated cooperation in economic games derive from sexual selection.
- Males higher quality not need demonstrate display attract attention.
- Our data, , show men with wide faces neither nor trusted female choice wider faced males-- experiments not address mate choice .
- second explanation by Zaatari and Trivers (2007) men with , faces that men with superior ability .
- situations involving aggression (p. 226) less .
- interpretation better our data.
- strength ability male faces (Sell al., 2009), male facial-width ratio suggested a signal dominance male-male competition correlates ratings propensity reactive aggression (Carré, McCormick, Mondloch, 2009).
- reactive aggression (altruistic punishment point-subtraction task) , validity participant perceptions untrustworthiness derive same , , a build.
- Men with `` wide faces exploit impunity.
- pro-pensity behavior our data created a generalized, association structure untrustworthiness.
- Weston et al. (2007), facial-width-ratio sexual dimorphism skull shape selected by female choice hominid line, our data suggest female choice ( , partner choice contexts by sexes), any effect aspect evolution, selected , rather than , sexual dimorphism, variation maintained selection display between males.
- decrease sexual dimorphism reduction physical robustness accompanying hominid evolution facilitated cooperation trust a society demands.
|All images||Male images||Female images|
|Gender and game behavior||r s||p||r s||p||r s||p|
|Male players (n = 36)|
|Female players (n = 107)|
|Note: Statistically significant results (p < .05) are highlighted in boldface.|