ps4029/30 perspectives on social attributions lecture 4
TRANSCRIPT
PS4029/30
Perspectives on social attributions
Lecture 4
1. Accounts of sym preferences (recap)
2. Does symmetry signal mate quality?
3. Is symmetry particularly attractive in mate choice relevant stimuli?
4. Is symmetry attractive independent of prototypicality?
5. Symmetric individuals are not only visually attractive
Lecture 3: Evolutionary advantage accounts of symmetry preferences
1. Perceptual bias accounts (recap)
Symmetry is attractive because :
- symmetric stimuli of any kind are processed more easily by the visual system
than relatively asymmetric stimuli
- as a byproduct of the tendency for symmetric objects to be prototypical
1. Evolutionary advantage view
Symmetry is attractive because of advantages associated with
choosing a symmetric mate
Non-Human Species Preferences for Symmetry
• Female barn swallows prefer males with symmetrical tail feathers
• Female Zebra finches prefer symmetrical males
Møller, 1994, Anim Behav
Swaddle & Cuthill, 1994, Nature
2. Does symmetry signal mate quality?
An important component of the evolutionary advantage view is that symmetry may signal qualities that are desirable in a mate (e.g. health, fertility)
[e.g. Thornhill & Gangestad, 1999]
This a hugely controversial issue but there have been somepositive relationships reported between symmetry and ‘matequality’
Symmetry and Quality
• Controversial area (Enquist et al., 2002)
• Non-humans– Symmetry associated with ejaculate quality in 3
ungulates (hoofed animals)– Antler symmetry positively related to immune
measures in reindeer
• Humans – Body symmetry positively related to sperm
number per ejaculate and sperm speed
– Breast symmetry positively correlated with fecundity
Manning et al., 1998, Evo Human Behav
Gomendio et al., 2000, Proc Royal Soc
Møller et al., 1995, Ethol. Sociobio
Lagesen & Folstad, 1998, Behav Ecol Sociobio
Symmetry and Quality IIHumans
– facial symmetry positively related to intelligence(Zebrowitz et al., 2000)– Body symmetry positively related to athletic
ability (Manning et al., 1998)
– Facial symmetry positively related to masculinity(another putative cue to immunesystem strength,
Gangestad & Thornhill, 2003)
[we’ll return to the issue of masculine facial proportions as a signal of immunity to infection in
lecture 7]
3. Is symmetry particularly attractive in mate choice
relevant stimuli?
Evolutionary advantage view emphasises importance of symmetry for ‘mate preferences/choices’
Perceptual bias views don’t
The Mona Lisa
The Thatcher Illusion
Eyes and mouth inverted
Symmetry Preferences in Upright and Inverted Faces
• Inversion disrupts normal face processing - inverted faces are processed more like visual objects than faces
• In regard to symmetry preference:• A simple perceptual bias view suggests symmetry
preference should be constant across orientation about a vertical axis
• Evolutionary Advantage view suggests symmetry particularly attractive in upright faces
Murray, Yong, & Rhodes, 2000, Psych Sci
Symmetry Preference in Upright and Inverted Opposite-Sex Faces
Little & Jones, 2003, Proc Royal Soc
4. Is symmetry attractive independent of prototypicality?
Central to the perceptual bias account is the notion that symmetry preferences are an artifact
of preferences for prototypicality
Evolutionary bias makes no such claim
Symmetry in Familiar Faces
• Even though symmetric version is less familiar (and less prototypical), symmetry is still preferred - Little and Jones, 2003)
Symmetric Asymmetric
Symmetry and prototypicality
• Symmetry attractive independent of averageness
(Rhodes et al., 1999)
Ratings of the attractiveness of faces and ratings of their distinctiveness (inverse of averageness) are -vely correlated
Ratings of the attractiveness of faces and symmetry are +vely correlated
Ratings of the attractiveness of faces and symmetry are +vely correlated when effects of distinctiveness are controlled usinga partial correlation design
5. Symmetric individuals are not only visually attractive
Perceptual bias account proposes that symmetry preferences are a byproduct of the visual system
Evolutionary advantage view proposes that symmetry is attractive because it signals an important underlying
quality (e.g. health)
Does symmetry predict attractiveness when you can’t see it?
Perceptual bias: NO (visual system needs symmetry as input)Evolutionary advantage: YES (underlying quality also reflected in
other ways)
Prototype faces tend towards very high symmetryComposites of symmetric faces more attractive than
composites of asymmetric faces (Penton-Voak et al., 2001)
Supports evolutionary advantage view (must be correlates of symmetry that are causing effect below because symmetry
not visible)
Composite of asymmetric faces
Composite of symmetric faces
Judged:
AttractiveHealthyFit
Judged:
UnattractiveUnhealthy
Unfit
Symmetry and attractiveness in other modalities
• Symmetric individuals have attractive voices• (Hughes et al., 2002)
• Symmetric individuals have attractive body odours• [NB - in men this effect only emerges when female
judges are in late follicular, fertile phase of menstrual cycle]
• Rikowski & Grammer (1998)
Lecture 4 Key Themes
1. That symmetry advertises qualities that are attractive in potential mates Is consistent with Evolutionary Advantage view
2. That symmetry is more attractive in mate-choice relevant stimuli thanOther classes of stimuli Is consistent with Evolutionary Advantage view(and also problematic for perceptual bias accounts)
3. That symmetry preferences occur for familiar faces and are attractive independent of prototypicality is problematic for the perceptual bias view
4. That symmetry predicts attractive in non-visual stimuli is problematic for the perceptual bias view and suggests attractiveness of symmetryreflects an attractive underlying quality
Next week: Does facial attractiveness signal health
Many theories of attraction (e.g. evolutionary advantage view) propose that facial attractiveness signals health
Next week we’ll review the evidence for this claim.