The dynamics of brain activation reflecting attractiveness in humans are unclear. Among the different features affecting attractiveness of the female body, the waist-to-hip ratio (WHR) is considered to be crucial. To date, however, no event-related potential (ERP) study has addressed the question of its associated pattern of brain activation. We carried out two different experiments: (a) a behavioural study, to judge the level of attractiveness of female realistic models depicting 4 different WHRs (0.6, 0.7, 0.8, 0.9) with and without clothes; (b) an EEG paradigm, to record brain activity while participants (heterosexual men and women) viewed these same models. Behavioural results showed that WHRs of 0.7 were considered more attractive than the others. ERP analyses revealed a different pattern of activation for male and female viewers. The 0.7 ratio elicited greater positivity at the P1 level in male viewers but not females. Naked bodies increased the N190 in both groups and peaked earlier for the 0.7 ratio in the male viewers. Finally, the late positive component (LPC) was found to be greater in male than in female viewers and was globally more marked for naked bodies as well as WHRs of 0.7 in both groups of viewers. These results provide the first electrophysiological evidence of specific time periods linked to the processing of a body feature denoting attractiveness and therefore playing a role in mate choice.
We performed two different experiments. In an initial behavioural rating task, female models with four different WHRs (0.6, 0.7, 0.8, and 0.9) were presented, either naked or clothed, and participants were asked to assess their attractiveness on a Likert scale. The second task included ERP measures and required indirect processing of the four WHRs. Both experiments included heterosexual men and women to test possible gender differences in the evaluation of attractiveness.
One hundred and ninety-two coloured images of 265 × 756-pixels (7 × 20 cm) representing entire female bodies in a neutral static position were created using N-sided Quidam 3.1.5 (www.n-sided.com), a software dedicated to professional game developers. This software allowed us to generate realistic female bodies by changing size, skin and hair colour, and clothes. We created 12 different realistic models under different conditions: (a) clothed and naked, (b) frontal and posterior view, (c) four waist-to-hip ratios (small = 0.6; medium = 0.7; large = 0.8; extra-large = 0.9), for a total of 16 conditions (2 clothes × 2 perspectives × 4 WHRs). Thus, each condition comprised a total of 192 stimuli. Skin colour was varied from dark (African) to light (Caucasian) to match the variations in light intensity produced by clothing. Additionally, all faces were manually blurred using Adobe Photoshop 6.0 to avoid an explicit influence of facial and expression features on the body processing. Examples of the stimuli are presented in Fig. 1a.
a Different categories of stimuli depicting four WHRs (0.6, 0.7, 0.8, 0.9) in dressed and naked models, presented in a posterior and frontal view. b Waist-to-hip ratio was calculated by dividing the width at the waist with the width at the hips
In this second study, participants performed an oddball task in which they were asked to respond to infrequent targets consisting either of clothed male bodies or pseudoanimals (also created using Quidam 3.1.5 software), depending on the session. They were asked to pay attention and to respond manually to targets by pressing a key with the index finger of the left or right hand. Response hand was counterbalanced across trails, with half of the subjects answering with the right index.
The experiment consisted of eight blocks of 192 trials presenting female bodies (12 different models × 16 conditions) and 21 trials presenting the target (pseudo animals or clothed males). This yielded a total of 96 trials for every female body category. In half the blocks, targets consisted of pseudoanimals, while in the other half, the targets were realistic pictures of men. The order of the blocks was randomized across subjects and target categories. The stimuli were presented for 250 ms, followed by a fixation cross, with an interstimulus interval (ISI) varying randomly between 1,000 and 1,200 ms.
WHR rating for naked and clothed bodies. Male and female groups show the same preferences when judging the WHRs of clothed and naked models. WHRs of 0.7 and 0.6 were considered more attractive when bodies were naked, whereas the clothed models were preferred at WHR ratios of 0.9. **p < .0001
N190 for naked and clothed bodies. A strong negative effect is observed between clothed and naked bodies at the N190 level for both groups of participants. Colours correspond to different conditions: naked (black) and dressed (red) models for men; naked (blue) and dressed (green) models for women (Colour figure online)
The positivity was significantly greater over the right than left ROIs, F(1, 18) = 4.55, MSE = 33.74, ε = 1, p < .05, ηp 2 = .20; mean values: 5.55 μV ± .44 vs. 4.57 μV ± .46, and for naked compared to clothed models, F(1, 18) = 44.88, MSE = 11, ε = 1, p < .0001, ηp 2 = .71; mean values: 5.94 μV ± .43 vs. 4.18 μV ± .38; see Fig. 7.
LPC of male and female participants for naked and clothed bodies. Naked bodies produced more positive responses than clothed bodies over the central leads for both groups of participants. However, male participants produced overall a more positive ERP than female viewers. Traces are shown for the three central electrodes (see Fig. 3 for electrode placement): colours indicate naked (black) and dressed (red) models viewed by men, and naked (blue) and clothed (green) models viewed by women. Yellow highlighted box indicates the time period in which the LPC was computed (Colour figure online)
Finally, our data revealed a heightened LPC for the most attractive (0.7) WHR. This is in keeping with findings reporting a greater LPC for attractive faces (Chen et al., 2012; Johnston & Oliver-Rodriguez, 1997; Marzi & Viggiano, 2010; Oliver-Rodríguez, Guan, & Johnston, 1999; Schacht, Werheid, & Sommer, 2008; Werheid, Schacht, & Sommer, 2007; Zhang et al., 2011). For example, Johnston and Oliver-Rodriguez (1997) observed an LPC in male viewers viewing female (but not male) faces that were manipulated to enhance attractiveness. The results revealed that the LPC, which showed a greater parietal than frontal scalp distribution, reflected the beauty rating of a female faces and not just attractiveness. In addition, they demonstrated that the modification of proportions producing facial traits of masculinity or femininity enhanced the beauty ratings as expected, along with the LPCs to female, but not male faces. Similarly, Oliver-Rodriguez and colleagues (1999) found that the average P300 and the mean subjective ratings were correlated, indicating that this late component was linked to the perceived degree of attractiveness. Of particular interest to our study, the authors also observed a stronger P300 or LPC for male viewers compared to female viewers, as observed in our results. Based on their interpretation of this phenomenon with faces, we would argue that if the LPC reflects the attractiveness of a stimulus for the participant, it is clear that the response must be greater for heterosexual male viewers as only female naked and clothed models were presented and a preference is to be expected. However, despite the lower emotional value of the stimuli for heterosexual female participants, ratings were similar between female and male viewers, reflecting as a similar value on the LRP for naked versus clothed bodies and for 0.7 WHRs versus the other ratios.
Reus est adversus quem contenditur, quia aut possidere veldebere dicatur. Ad probationem actoris pertinet si obtinere velit, ut id quod intendit,probet. Actore enim non probante, qui convenitur,(36) etsi nichil praestiterit, obtineat, quia rei favorabiliores sunt quamactores. His aequipollenter dicitur: iure promptiora sunt ad absolvendum quam adcondempnandum. Cumque reus in exceptione actor est, ipsum quod excipit, probare debet . .. Accusare omnibus permissum est, his exceptis. Propter sexum prohibetur mulier, propteraetatem pupillus, propter sacramentum militare qui stipendium meret, idest miles, proptermagistratum ut consul et praetor, propter delictum ut infames, propter turpem quaestum, uthi qui nummos ob accusandum vel non accusandum acceperint, propter conditionem, ut liberticontra patronos, propter suspicionem calumpniae, ut qui falsum testimonium subornatidixerunt. Ratione paupertatis, ut hii, qui minus habent L. aureis . . . Testium ratio est.Ad testimonium cogi possumus per iudicem et improbe versantes absque praescriptione foricoherceri. Aliquando excusamur sive in omnibus causis ut senes valitudinarii sive inaliquibus, veluti in publico crimine. Contra cognatum(37) admittimur volentes. Et quandoque excusamur et quandoque cogi possumusinviti. Interdum inviti excusamur et volentes repellimur, ut liberi contra parentes eteconverso. Testium quidam iudicis officio, quidam exceptione(38) removentur. Iudicis officio propter dicendi suspicionem, exceptioneveluti qui dampnati sunt de carmine famoso, quos leges iubent esse inprobos etintestabiles(39) . . .Iudicium est actus ad minus trium personarum, actoris intendentis, rei intentionemevitantis, iudicis in medio cognoscentis. 2b1af7f3a8