Women "Advertise" Fertility

Dik Zak writes with word of a paper published in the journal Hormones and Behavior. A study found that women take greater care over their appearance when they are at peak levels of monthly fertility. The researchers took two photos of each of 30 women, one near ovulation and one at the other end of her cycle. They then showed the paired photos (with faces obscured) to a group of observers, who were asked to judge in which photo the women were trying to look more attractive. The observers chose the "high fertility" subject nearly 60% more of the time than would be expected by chance.

Comments

60% more than chance?

[Anonymous Coward]

The summary is misleading.

The observers chose the "high fertility" subject nearly 60% more of the time than would be expected by chance That would be 80% of the time whereas in the article it states the percentage was 60% of the time, not 60% more.

No, 60% more

[Chris Burke]

Not 60% of the time, but 60% more than expected if it were chance alone. So more likely 1.6 * (30*.5) = 24/30, not 18/30.

But of course the actual number isn't in the article.

Re:No, 60% more

[Surt]

The article is clear on this, the slashdot summary is wrong. It's 60% right guesses for 42 guessers against 30 pictures, over a thousand total guesses, with 60% right instead of 50% right.

Re:No, 60% more

[Surt]

30 is a low sample size, but would not be unusual in psychology studies. There are statistical tests you can perform to find out the minimum effect size to declare significance. I've seen studies with meaningful results in as few as 8 samples.

Nevertheless, this particular study had 1260 samples. 42 guessers * 30 guesses each. More than a thousand samples is plenty for significance.

Re:No, 60% more

[Chris Burke]

Where the word 'more' came from, other than slashdot summary, I don't know.

It came from the New Scientist article which was linked from the summary at the end of the sentence: "The observers chose the "high fertility" subject nearly 60% more of the time than would be expected by chance, according to the NewScientist.com writeup."

So like I was saying, it isn't the slashdot summary, it's Daily Mall and New Scientist which are contradicting each other.

Thank goodness for the real study, though, which makes it clear that it is New Scientist which is incorrect.

Re:No, 60% more

[Surt]

8 people have a physical ailment. 4 people receive surgery, 4 don't. The 4 receivers live, the 4 non-receivers all die.
You have the ailment. Surgery or no surgery for you?

2 people guess a million times. They each get the right answer 600,000 each. Do you still assume it's a random guess? You may not believe that their power generalizes, but you darn well better believe in their power.

Re:No, 60% more

[StikyPad]

Well, yes and no.. there are postfertilization protections as well, so just because one ovulates doesn't mean the birth control wasn't working, just not working 100% (which it doesn't claim to). Still, you're right that not taking the pill will likely cause ovulation, so it gets back to the correlation/causation debate. At any rate, the study indicated an increase in "forgetfulness" around the time of would-be ovulation, as compared to the placebos taken during menstruation.

Re:60% of 30?

[Surt]

The article and summary are in disagreement. Choosing to assume the article is more likely to be right, it is 60% right guesses vs expected 50% right guesses.

However, also omitted from the summary is 42 guessers guessing on the 30 dress-up-women in the study. That's 42x30 guesses, with a 60% correct guess rate overall. 60% with more than a thousand sample points is well within the usual scientific standard for statistically significant.

FULL ARTICLE

[brian0918]

The full article can be found here.

About Statistical Significance

[flynt]

I am a statistician, and reading through the comments hear, am saddened that many readers claim that "statistical significance" could not have been achieved in this study because of a sample size of 30 women. First, that's only part of the random sample in this study, the other part is men sampled to judge the pictures.

Second of all, I have looked up the actual publication in "Hormones and Behavior", and the p-value associated with their main test is .01, which usually signifies statistical significance.

Ultimately, determining whether some difference in populations is due to chance depends on more than just sample size. It depends on how large of a difference you want to detect, and the variance of the measurements within a group. Of course, larger sample sizes help, but it ultimately depends on what you're studying, and the design of the experiment.

So while I definitely applaud being sceptical of all statistics, I urge you to look up the actual publications, read the methodology, and then decide if the results are something you believe. Kneejerk reactions to n = 30 don't really help anyone though.

I have not read through this publication in its entirety yet.

Partial article text from ScienceDirect

[shrubya]

To put this matter to rest, here are some relevant paragraphs of article text (thank you, worldwide university subscription):

Method
Procedure: photographic stimuli

Thirty women from the UCLA campus (mean age = 21.07 years old; SD = 2.35; range 18-37) posed for two standing full-body digital photographs with their hands placed at their sides (Canon PowerShot S410, 4.0 Megapixels). Women identified themselves as African American (n = 1), Asian American (n = 10), Caucasian (n = 6), Hispanic/Latino (n = 7), and mixed race or "other" (n = 6). One photograph was taken on a high fertility day of the cycle (follicular phase) and one on a low fertility day of the cycle (luteal phase). Photographs were taken in the same location under standardized lighting conditions against a plain blue background. All women reported regular menstrual cycles (ranging between 26 and 35 days), were partnered (involved in a "committed romantic relationship" with a man), and none had used oral or other hormonal contraceptives within the last three months. Because previous studies have found stronger ovulatory effects in partnered than in non-partnered women (e.g., Havlicek et al., 2005 and Pillsworth et al., 2004), we limited our investigation to partnered women.

Session scheduling and luteinizing hormone (LH) testing were conducted using the procedures described in Gangestad et al. (2002). There were three sessions--an initial session for cycle history assessment and scheduling and subsequent high and low fertility sessions. After initial sessions, women were scheduled to return for the next possible session (low or high) given their current cycle day. Low fertility sessions were scheduled to occur 4-10 days prior to the estimated day of next menstrual onset. Actual menstrual onset was reported by 66.7% of women after their low fertility session; for the balance of participants, menstrual onset was estimated using cycle length and the last date of menstrual onset. On average, based on these information sources, low fertility sessions took place 5.87 days prior to menses (SD = 2.5; three women participated within 48 h of menstrual onset and possibly could have experienced premenstrual symptoms; therefore, days-to-menstrual-onset is included in the analyses presented below). High fertility sessions were scheduled to occur 15-17 days prior to the next estimated menstrual onset. Participants also reported to the laboratory to complete urine tests beginning two days prior to their high fertility session and continuing for three days after this session or until an LH surge was detected. Using an unmarked commercially available urinary stick ovulation test (Clearblue(TM)), all women were judged to have an LH surge between three days after and two days before their high fertility session. An LH surge typically proceeds ovulation by 24-48 h (Guermandi et al., 2001); thus, all women were likely to be near ovulation during their high fertility session. Within the fertile window of the cycle, conception risk increases as ovulation approaches (Wilcox et al., 1995). We therefore estimated days-to-ovulation (by adding two to days-to-LH surge; mean = 3.03, SD = 1.40) and included this estimate in the analyses reported below.

These 30 women were a subset of 58 originally recruited for the study. Women ineligible for inclusion in the study either showed no evidence of an LH surge (n = 4), were rescheduled for low fertility sessions (due to their own time constraints) on days falling outside of the range of the luteal phase days (n = 3), did not consent to having photos taken (n = 7), consented to having their photos taken but did not consent to having their photos judged by people other than the researchers (n = 7), or did not complete all sessions (n = 7). There were no significant differences in relationship satisfaction, sociosexuality (Simpson and Gangestad, 1991), age, or relationship length between women retained in the study and those who were ineligible.

Participants were blind to the purpose of the stu

Why Grad Student Research is terrible...

[tgatliff]

This is a classic example why grad student research, which this strongly suggests is so bad. Yes, a female will on average dress more attractive during the end of her cycle, but not directly caused by ovulation itself. The underlying reason is progestogen. (progestin in females taking birth control. ).

Why is this? Simple. For men the primary mechanism underling sexual desire is 5a-dehydro-testosterone (DHT), not directly from testosterone as many people think. Without DHT, sexual desire in men is very unlikely. This is the main reason why many bodybuilders lack sexual desire during the "on season". This has been known for some time, and in Europe a synthetic form of DHT (1-methylated DHT) called Proviron is used for treating sexual desire problems. In fact, its main side effect is an uncontrollable erection. Go figure...

In females, progesterone is used in the final stages of ovulation, but it has powerful neurological effects on sexual desire similar to DHT, but unfortunately this mechanism is not completely understood yet. Eventhough causes of why certain females have have lack of sexual desire are many, for physical reasons progesterone typically is at the top of the list.

Estrogen on the other hand which is strong in the early part of a womens cycle, from a nearuological effects standpoint, produces the same effect in both women and men, in that it increases emotion. Because fat will increase estrogen in women and men, this is strong reason why overweight people are typically more emotional.

Let me clear this up

[6ame633k]

Oh for gods sake - I don't need scientific research to tell you why women are more attractive while they are ovulating. Most of us feel like crap before, during and after our period and, as a result, we don't want anyone to bother us so we spend less time on our appearance. However, when your near ovulation you are typically more interested in sex because, well, you don't feel like crap. So more time and effort go into hair and makeup as a result. Case closed :)

Re:Not statistically independent, however

[aethogamous]

For sake of argument, assume that there is an objective way to measure who takes greater care of their appearance and that all 42 judges are experts at measuring that and never wrong. In that case, these results boil down to 18 out of 30 women taking better care of their appearances during one of their ovulation phases than during one of their non-ovulation phases. When you combine that with the possibility that some of the judges could be wrong (thus increasing the expected variance), it's even less significant - not more. I'm going to go with Scooter on this one.

The published analysis is more analogous to saying that each women has a score that measures how much more or less attractively they dress during ovulation. In the article's case the score is defined in terms of the percentage of observers who think that a women is more attractively dressed during ovulation, with scores ranging from 0% to 100%. The 42 observers are used to estimate that score for each women. The reported percentage of 59.5% is the mean of these scores, and is not a percentage of the 30 women.

The analysis asks whether this mean score is greater than 50%. Whether or not significance is achieved with 30 observations in this case depends on the distribution of these 30 scores, which is not given in the article. Using only the information about the mean (59.5%), using a t.test (the actual analysis was more sophisticated, and included covariates) we can easily constuct p-values ranging from 0.1404 (12 women score 0%, 18 score 100%) to 5.969e-12 (15 women score 55%, 15 women score 65%)

It is possible (but presumably unlikely) that more women actually looked worse to a majority of the observers during ovulation and still get a mean score of 65% (for example if 22 women scored 45% and 8 scored 100%).

Moderators: parent post is GARBAGE!

[Tim]

Moderators, for the love of....don't just give high ratings to people who post technical-sounding gibberish!!

The parent post is spreading misinformation with regard to the link between libido and di-hydro-testosterone (you'll note that he got the abbreviation incorrect, and attached a spurious "5a" to the front, because he confused the name of the enzyme -- 5-alpha-reductase -- responsible for DHT formation with the chemical itself!)

I'm not going to claim that DHT isn't involved with male sex drive, but it's certainly not the "primary mechanism" behind male libido. One needs only refer to the volumes of studies done on the relationship between selective serotonin reuptake inhibior antidepressants ("SSRIs", e.g. Celexa, Prozac, Paxil) and libido suppression to see that the issue is more complicated than a single hormone imbalance.

What makes this really galling, however, is that the guy has the guts to criticize real scientific research before spouting this crap, and you folks take it as some sort of authority!

Why slashdot postings can be terrible...

[bogd]

but not directly caused by ovulation itself. The underlying reason is progestogen.

Who said it was caused by the ovulation itself? The article was just saying that women tend to dress more attractively when they are fertile. Whether that is caused by the ovulation itself, by progesterone, or random firings of the synapses is something that we still don't know. progesterone is used in the final stages of ovulation

1) Please stop mixing up progesterone (the natural hormone) with progestogen (class of hormones) and progestin (synthetic hormone).

2) Take a look here. You will see the evolution of hormone concentrations over the course of the menstrual cycle. If what you are saying was true (and the effect mentioned in the paper really was caused by the progesterone), you would expect to see an increased effect when progesterone levels hit their peak - somewhere in the middle of the luteal phase. (and no, that is not "in the final stages of ovulation")

But let's look at the article again:

[the photos were taken] one on a high fertility day of the cycle (follicular phase) and one on a low fertility day of the cycle (luteal phase).

What do you know? Those days in the luteal phase are actually low fertility days. Days in which women don't care as much how they look. Precisely the opposite of what you were saying...

Also, I don't understand what the second paragraph (the one about DHT) has to do with anything. It's not related to the article, it's not related to the other paragraphs in your post, and it's also wrong. Have a look here - mesterolone (the active ingredient in Proviron) is not hydrogenated - so it is a relative of testosterone, rather than DHT (compare it with the images found here).

The conclusion? You don't know what you are talking about, but you go around criticizing other people's research. The fact that your post got a "+5, informative" modifier only proves that people will believe anything that sounds technical, even if it's pure garbage...

Save yourself the torture!

[PowerMacDaddy]

Download a copy of Female Alert System. This lovely piece of software has kept me from going nuts trying to figure out why one day my wife is all over me and I can do no wrong, to the next day she wants nothing to do with me and I can do no right. Seriously, this little freeware from Heaven is a Godsend. All you do is plug in her last start date and cycle length and it calculates what mood she's in for any given day. Ridiculously accurate, so you know what days to suggest that you need to buy a new MacPro and 1TB RAID, and what days to "work late" (fragging.)