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Arching the Back (Lumbar Curvature) as a Female Sexual Proceptivity Signal: an Eye-Tracking Study

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  • Linnaeus University, Kalmar, Växjö, Sweden
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Abstract and Figures

It is common in studies of human mate preference to have participants judge the attractiveness of photographs in which models adopt a neutral facial expression or a neutral body posture. However, it is unlikely that humans adopt neutral expressions and postures in normal social circumstances. One way in which posture can vary is in the curvature of the lower spine. In some non-human animals, a “lordotic” posture (in which the lower spine is curved towards the belly) is associated in females with readiness to mate. In humans, this posture may serve a similar function, attracting heterosexual men. In this study, participants were presented with computer-generated images of female bodies in which the back curvature was systematically manipulated. The result showed that small changes in lumbar curvature are associated with changes in the perception of attractiveness. Specifically, the result showed that there is a relationship between the range of the back curvatures used in this study and attractiveness, such that increasing the curvature increased the perception of attractiveness. Additionally, as the curvature increased, participants looked longer and fixated more on the hip region of the female bodies. This paper argues that the attractiveness of women in lordotic posture is due to a conserved mechanism across the taxa which signals proceptivity to men.
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RESEARCH ARTICLE
Arching the Back (Lumbar Curvature) as a Female
Sexual Proceptivity Signal: an Eye-Tracking Study
Farid Pazhoohi
1
&James F. Doyle
2
&Antonio F. Macedo
3,4
&Joana Arantes
1
Published online: 25 October 2017
#Springer International Publishing AG 2017
Abstract It is common in studies of human mate preference
to have participants judge the attractiveness of photographs in
which models adopt a neutral facial expression or a neutral
body posture. However, it is unlikely that humans adopt neu-
tral expressions and postures in normal social circumstances.
One way in which posture can vary is in the curvature of the
lower spine. In some non-human animals, a lordoticposture
(in which the lower spine is curved towards the belly) is as-
sociated in females with readiness to mate. In humans, this
posture may serve a similar function, attracting heterosexual
men. In this study, participants were presented with computer-
generated images of female bodies in which the back curva-
ture was systematically manipulated. The result showed that
small changes in lumbar curvature are associated with changes
in the perception of attractiveness. Specifically, the result
showed that there is a relationship between the range of the
back curvatures used in this study and attractiveness, such that
increasing the curvature increased the perception of attractive-
ness. Additionally, as the curvature increased, participants
looked longer and fixated more on the hip region of the female
bodies. This paper argues that the attractiveness of women in
lordotic posture is due to a conserved mechanism across the
taxa which signals proceptivity to men.
Keywords Lumbar curvature .Lordosis .Proceptive
behavior .Receptivity .Sexual behavior .Eye-tracking
Human sexuality is not unique, nor is human sexual
behavior totally different from that of other
animals.”—Alan F. Dixson 2015
There exist sex differences in courtship and mating behav-
ior. These differences in mating behavior are due to an inter-
play between endocrine and genetic factors throughout devel-
opment and life span. Behavioral sex differences are affected
by organizational hormones during all stages of organisms
lives, with critical prenatal and pubertal periods (Berenbaum
and Beltz 2011). Prenatally, hormones influence brain devel-
opment resulting in permanent and pronounced differences in
sex-typed behavior beginning at puberty and expressed in
adolescence (Berenbaum and Beltz 2011). The hypothalamic
ventromedial nucleus (VMH) is a site of ovarian hormone
action critical to the lordosis response. Sex differences in neu-
ral circuitry and neurochemistry of the VMH have been
reviewed elsewhere (Flanagan-Cato 2011). Lordosis, or the
arching of the back, is a female-specific copulatory behavior
which indicates that the female is sexually receptive (Beach
1976). In many female mammals, VMH is involved in the
display of proceptive and receptive behaviors (Flanagan-
Cato 2011; Henley et al. 2011), and lesions in this center
reduce sexual receptivity and lordosis behavior in female rats
(Clark et al. 1981), hamsters (Malsbury et al. 1977), guinea
pigs (Goy and Phoenix 1963), ferret (Robarts and Baum
2007), sheep (Clegg et al. 1958), cats (Leedy and Hart
1985), and primates (Aou et al. 1988). As lesions to the
VMH of female whiptail lizards inhibit receptive sexual
*Farid Pazhoohi
pazhoohi@gmail.com
1
Department of Basic Psychology, School of Psychology, University
of Minho, Braga, Portugal
2
Stillwater, MN, USA
3
Vision Rehabilitation Laboratory, Department and Centre of Physics,
University of Minho, Braga, Portugal
4
Department of Medicine and Optometry, Linnaeus University,
Kalmar, Sweden
Evolutionary Psychological Science (2018) 4:158165
DOI 10.1007/s40806-017-0123-7
Content courtesy of Springer Nature, terms of use apply. Rights reserved.
... Intrasexual competition in women is influenced by traits that are important in intersexual selection in men, such as desirable physical traits [1], attractive features [2], and sexual receptiveness [3]. Given the importance placed on attractive features by men, women may compete with other women to enhance specific traits in order to increase their mating success. ...
... Importantly, women are also aware of other women's attractiveness and enhancement strategies [7] and are likely to utilize retention strategies to keep their current partners [2,8]. Studies have also shown that lumbar curvature (i.e., lordosis) in women is considered attractive, due to its role in bipedal fetal load [9] and sexual receptiveness [3]. ...
... The present study is concerned with this latter factor [3,9]. While conceptually similar, there are two different evolutionary hypotheses for the attractiveness of arched-back postures, with one focusing on an arched back as a morphological adaptation in women bodies, and the other emphasizing lumbar curvature as a nonverbal behavioral adaptation. ...
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Previous research has shown that women may use self-enhancement strategies to compete with one other. Lumbar curvature in women is considered to enhance a woman′s attractiveness, potentially due to its role in bipedal fetal load and sexual receptiveness. The current study investigated the role of lumbar curvature on women’s perceptions of sexual receptiveness as well as its role in women’s intrasexual competitiveness. Study 1 (N = 138) tested and confirmed that women’s intrasexual competition influences their perception of sexual receptivity of women as a function of lordosis posture depicted in a standing posture. Study 2 (N = 69) replicated these results and extended them to other postures, namely, the quadruped and supine positions. Study 3 (N = 106), using a two-alternative forced-choice task, revealed that other women perceive relatively larger arched-back postures as more threatening to their relationship and frequently as being more attractive. Collectively, this work suggests that women consider a lordotic posture in other women as a signal of sexual receptivity and perceive it as a threat to their relationship. This research provides robust support for the sexually receptivity hypothesis of lumbar curvature, questioning the alternative morphological vertebral wedging hypothesis.
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... As predicted, no gender difference was found between observers in the positive effect of high heels on perceived attractiveness (H2), which is in line with previous findings [21,30]. This supports the idea that adequately perceiving the sexually attractive features of the female body is an essential part of women's mate choice strategies and intrasexual rivalry [36]. ...
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... Research Design: Descriptive research design is used. Descriptive design involves the accurate description of characteristics of individual, situation, or group, and the frequency with which a certain phenomenon occurs in natural setting without imposing any control or manipulation (Pazhoohi et al., 2018). ...
... Posture is the position and relative arrangement of the body parts (e.g., Canales et al., 2010). It has been shown that nonverbal changes, including postural changes, reflect an individual's affective state and act as gateways in social communication (e.g., Cazzato et al., 2012;Grammer et al., 2000;Mehrabian, 1969;Pazhoohi et al., 2018;Pazhoohi et al., 2020). An enormous volume of research has mainly defined postural effects, such as postural openness and postural relaxation, on social impressions, and showed how these postural changes modulate interpersonal attractiveness and dominance (e.g., Burgoon, 1991;Hall et al., 2005;Mehrabian, 1969;Vacharkulksemsuk et al., 2016). ...
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