Tuesday, December 29, 2009

Dead salmon CAN think! Or an argument for multiple comparison corrections

Just over five years ago, a New Square fish store owner and his employee claimed to have had a talking carp:

Mr. Rosen said that when he approached the fish he heard it uttering warnings and commands in Hebrew.

"It said `Tzaruch shemirah' and `Hasof bah,' " he said, "which essentially means that everyone needs to account for themselves because the end is near."

The fish commanded Mr. Rosen to pray and to study the Torah and identified itself as the soul of a local Hasidic man who died last year, childless. The man often bought carp at the shop for the Sabbath meals of poorer village residents.

Few believed them, though many jokes were made such as the gefillte fish manufacturer who considered taking on the slogan "Our fish speaks for itself".

Now neuroscientists have documented brain activity, not just in a live carp of the story, but in a dead salmon, in the paper, Neural correlates of interspecies perspective taking in the post-mortem Atlantic Salmon: An argument for multiple comparisons correction. As they put it in their Methods section:

Subject. One mature Atlantic Salmon (Salmo salar) participated in the fMRI study. The salmon was approximately 18 inches long, weighed 3.8 lbs, and was not alive at the time of scanning.

Task. The task administered to the salmon involved completing an open-ended mentalizing task. The salmon was shown a series of photographs depicting human individuals in social situations with a specified emotional valence. The salmon was asked to determine what emotion the individual in the photo must have been experiencing.

Just picture the scene for a moment. I would love to talk to the research assistant who had to talk to the salmon and show it pictures. What kind of "mentalizing" does a person have while speaking to a dead fish?

The conclusion:

Can we conclude from this data that the salmon is engaging in the perspective-taking task? Certainly not. What we can determine is that random noise in the EPI timeseries may yield spurious results if multiple comparisons are not controlled for. Adaptive methods for controlling the false discovery rate and familywise error rate are excellent options and are widely available in all major fMRI analysis packages. We argue that relying on standard statistical thresholds (p < 0.001) and low minimum cluster sizes (k > 8) is an ineffective control for multiple comparisons. We further argue that the vast majority of fMRI studies should be utilizing multiple comparisons correction as standard practice in the computation of their statistics.

The study was also covered by Science News in an article on lack of replicability of fMRI experiments. The Science News story includes a quote that is a good idea for everyone, whether or not they do fMRI experiments: “Statistics should support common sense. If the math is so complicated that you don’t understand it, do something else.”

When this study wins the Ignobel Prize, you can say you saw that prediction here first.

Tuesday, December 15, 2009

Is it possible to restore the norm of no premarital sex?

News today about gaps in sex education has a fantastically clear quote about the goals of conservative policy towards sex education:

"I don't think we'll be able to overcome this problem unless we restore the social norm of not having sex and not getting pregnant before marriage," said Peter Sprigg, senior fellow for policy studies at the Family Research Council.

Social conservatives do not generally support research about social norms about sexuality, so we do not know as much about sexual norms as we would otherwise. According to the earliest representative studies by sociologist Ira Reiss, the attitudes to allow what Ira Reiss called "permissiveness with affection" started shifting in the 1940s, and the shift was well underway by 1950 and definitely by 1960 when Ira Reiss wrote Premarital Sex in America (the link goes to the actual book). It seems unlikely that such a long-standing attitude shift could be easily reversed. By now, it is the standard that even many Evangelicals follow. If they marry right after college, it's possible they may abstain, but if they marry later, it's very unlikely, and many do marry later.

I would argue that permissiveness with affection is not a policy issue. No public health problems result from premarital sex within long-term committed monogamous relationships. Disease spread is self-limiting. Still, if changing that social norm is a worthy public policy goal, they have to look to more recent trends first.

One norm that has changed more recently are attitudes towards what Reiss calls "permissiveness without affection:" just as AIDS was emerging in the early 1980s, academics were declaring this to be the new norm. From the poll data in the link (which I would guess is an incomplete picture of the available data), it looks like endorsement of the norm may have declined with AIDS/HIV, and has begun to reemerge to some extent and even become part of public discourse, with everyone having heard of the idea of "Friends with Benefits". Unlike permissiveness with affection, there is some degree of a public health justification due to the herpes and HPV risks.

But that means you have to acknowledge that that nearly all Americans have premarital sex, and teach real sex education to protect them.

And then you have to think of a policy that can change social norms. Incidentally, changing social norms would seem to be totally inconsistent with a limited government of the sort that Conservatives say they want.

Open letter to Senator Lieberman

Dear Senator Lieberman,

As a Harvard Health Policy PhD and Jew, I am sad to hear that you are weakening health care reform.

As a Health Policy PhD, I refer you to my professors in the Harvard Health Policy program, who say the original Senate health care bill is the best available solution.

As a Jew, I remind you that the Rabbinic Sages teach us not to be like the men of Sodom who would say שלי שלי ושלך שלך "What is mine is mine and what is yours is yours." The Sages taught that justifying inequality is not just negligence, but actually evil.

The present US system could be a model for Sodom: discounted prices to the rich/insured/healthy and inflated prices to the poor/sick/uninsured. Any solution that perpetuates inequalities between privileged/healthy and poor/sick perpetuates the health care system of Sodom.

Strong health care reform is a policy and Jewish imperative.

Janet Rosenbaum, Ph.D. Health Policy, Harvard 2008
Johns Hopkins Bloomberg School of Public Health

Monday, December 14, 2009

Quantifying and qualifying casual sex

A recent paper compares measure of "psychological wellbeing" between people whose most recent relationship was casual versus serious, and finds no difference. The paper motivates itself by the speculation in public discourse and the teachings of abstinence-only sex education that casual sex is harmful.

The qualitative research on the subject of casual sex seems pretty clear that, to the extent that they exist, the harms of casual sex would be unlikely to be found on a psychometric measure. Kathleen Bogle's qualitative study found that college-aged women feel frustrated and sometimes their feelings are hurt by differing expectations, which is also consistent with what Laura Sessions-Stepp reports in her journalistic book. I haven't ever seen anyone suggest higher rates of mental illness among people who have casual sex. It seems highly unlikely that casual sex poses a public mental health problem. (Casual sex does likely increase the total lifetime number of sex partners, so increases STD risk, but that's not the main issue here.)

The lack of a quantitative measure for romantic frustration doesn't make it unimportant. Just as quantitative research finds that married men seem to be in better physical and mental health than unmarried, but no difference for women, doesn't diminish the importance of the desire of many unmarried women to be in committed relationships. Likewise, quantitative research finds that people with children are more unhappy than people without, and yet there is an entire medical subfield dedicated to making people unhappy by helping them have children. (Likewise, my understanding is that US medical doctors stopped performing sex reassignment surgery after quantitative studies found no improvement after surgery, and yet qualitatively transgendered people who choose surgery report an improvement.)

Intangibles are important. Keep those qualitative studies coming.