What psychology experiment would you love to carry out if neither ethics nor practical reality stood in your way? For the August issue of Psychology Today, I asked several PT bloggers this question and printed four responses. Here's a more complete roundup of their insights.

Musical Storks
I would collect all newborn babies and randomly reassign them to new parents. I'm confident that we will confirm the 50-0-50 rule: Adult personality is roughly 50% genetic, 0% how they are raised by their parents, and 50% socialization outside the family by peers and friends. I think we will discover that within a broad range, it doesn't really matter how parents raise their children. Parents are enormously important for children, not because they raise them, but because they give them their genes.
-Satoshi Kanazawa (The Scientific Fundamentalist) is an evolutionary psychologist at the London School of Economics.

Universal Grammar
I would entirely determine the sentences and words children are presented with during their infancy and childhood. For instance, you could entirely deprive children of examples of some linguistic constructions. You could also add numerous non-grammatical constructions. Then see whether children develop a normal linguistic competence. If so, that would be very strong evidence that we possess a dedicated cognitive mechanism to help us acquire language.
-Edouard Machery (Experiments in Philosophy) is a philosopher of psychology at the University of Pittsburgh.

The 64-Thousand Dollar Question
What I'd really like to do is an experiment with massively high (monetary) stakes. I've done some research on gambles and financial risk taking, usually with payouts of a few dollars. However, this isn't ideal. People might make different decisions about high- and low-stakes financial risks. And they might make different decisions about real vs. hypothetical gambles. So, what I modestly request is a billion dollars, so I can offer a 1,000 people million-dollar payouts. That should appease my curiosity.
-Dan Goldstein (Decisions, Decisions) is a psychologist at London Business School.

Spitting Image
I thought it would be revealing to identify identical twins reared apart, obtain photographs of their children before the children met, and get preference ratings from the children in each family. Specifically, "half-siblings" would be shown an array of photographs including their cousin and several age- and sex-matched individuals. They would be asked to rate these individuals along such dimensions as attractiveness and desirability. We tend to be attracted to people with whom we share similarities. Would these "half-siblings" be socially attracted to one another as playmates or companions, over and
beyond what they feel toward their ordinary friends?
-Nancy Segal (Twofold) studies the psychology of twins at California State University, Fullerton.

Another Man's Shoes
As a philosopher, I'm acutely aware of being trapped within my own subjective experience. So I would construct a machine that would allow me to take the perspective of my subjects, to experience reality as they do. Then I'd gather a group of people I can least relate to-a serial killer who eats his victims, a Yankees fan, a passionate Hillary Clinton supporter, someone who thought the movie Crash was brilliant, Kim Jung Il -hook them up to the machine and learn what it's like to see the world through their eyes.
-Tamler Sommers (Experiments in Philosophy) is a philosopher at the University of Minnesota, Morris.

Enter the Matrx
I would create an "experience machine" that gave people the illusion that they were living a vibrant and exciting life. If you entered the machine, you would have the feeling that you were a successful rock star (or whatever your dream job might be), with tons of adoring fans, a loving family, and a challenging and rewarding career. But none of those things would actually be happening. Philosophers have long wondered whether people care only about their own feelings of happiness or whether they truly do want to be accomplishing something meaningful in their lives. If we could offer people the choice to go into this machine, we would at last have a good way of figuring out what the answer really was.
-Joshua Knobe (Experiments in Philosophy) is a philosopher at UNC

For Better or Worse
I'd like to take couples who are living together and randomly assign half of them to marry and the others to stay unmarried. Then we could really know something about the implications of co-habitation vs. marriage. More outrageously, take people who are not in a serious romantic relationship, and assign half of them, at random, to marry. Single people are randomly assigned to a spouse who is chosen at random, or to a spouse who fits their description of their perfect partner, or to stay single. Who do you think would end up the happiest a decade later? Same for divorce. If married parents are already at each other's throats, is it better for the children if they divorce, or stay together? Randomly assign half of them to divorce, and half to stay together; then we'll see. Now take married couples who say they are happy and are not considering divorce. Randomly assign half of them to divorce! Now who will be happier ten years hence?
-Bella DePaulo (Living Single) is a psychologist at the University of California, Santa Barbara.

Making Arrangements
Clearly, Eli and I are not sufficiently diabolical. Even without ethical restrictions on our research, we couldn't come up with anything even approaching the cruelty of MTV's X Effect. This reality gem has confirmed such counterintuitive romantic principles as (a) put two exes in a room overnight and they might wonder if there is still some chemistry and (b) watching your boyfriend or girlfriend hook up with his or her ex is upsetting. First, we'd divide the United States into three countries. One country would have the current marriage system, which maximizes autonomy: You know yourself best, so you are free to choose your own partner. In the second country, social scientists will assign you to your marriage partner based on their empirically validated algorithm. In the third country, you are paired with your marriage partner randomly. So now the question: Which country would have the lowest divorce rate? The greatest marital satisfaction? The lowest rate of intimate partner violence? Country #3 might not be as bad as people think: Spend enough time in someone's presence, and interesting things can happen. Even MTV knows that.
-Eli Finkel and Paul Eastwick (The Attractionologists) are social psychologists at Northwestern University

The Mannequin Within Us All
And here's my impossible experiment: What happens when you lock someone in a room with a mannequin for a month? Back in 1997 I tried this with my mom and my mannequin (Mandy), with a little help from a local science teacher and my friend Glen. It ended in disaster:

UPDATE: I'd forgotten about this, but the British Psychological Society's Research Digest blog once did a similar roundup, in which several researchers answered "What's the most important psychology experiment that's never been done?" Many of their suggestions are impossible or unethical. Check it out.