TORONTO—Corporal punishment has long been a hotly debated subject, with conflicting study results and opposing ideologies feeding the fire. Now the results of a five-year effort to review the scientific literature are in: a task force appointed by the American Psychological Association concludes that "parents and caregivers should reduce and potentially eliminate their use of any physical punishment as a disciplinary measure."

The recommendation was announced at the APA's annual meeting here today by the task force chair, psychologist Sandra A. Graham-Bermann of the University of Michigan-Ann Arbor. In a presentation, she explained that the group of 15 experts in child development and psychology found correlations between physical punishment and an increase in childhood anxiety and depression, an increase in behavioral problems including aggression, and impaired cognitive development—even when the child's pre-punishment behavior and development was taken into consideration.

Contrary to conventional wisdom, you can get too much of a good thing. A favorite song can get downright annoying after a few dozen listens, and a preferred lunch can become old hat if packed too many times.

Could simply recalling other tunes, or meals, bring back your original enjoyment? Some recent research suggests this kind of “virtual variety” might just do the trick.

The stakes might be higher than you think. “Satiation is a real problem,” says Jeff Galak, a marketing professor at Carnegie Mellon University and the lead author of the study published recently online in the Journal of Consumer Research. “If we stop enjoying the things we enjoy, we’ll be forced to find the next best thing. And if that continues in perpetuity, we’ll never be happy with what we have.”

Editor's Note: This story is part of an In-Depth Report on the science of beauty. Read more about the series here.

What makes beauty? A flawless complexion? Inner serenity? A free gift-with-purchase just in time for Mother's Day (nudge, nudge—Sunday, May 10)?

Philosophers, artists and everyday consumers have long pondered the question of what beauty, that amorphous it-factor, really is. Science has taken a stab at the question, too, and the range of answers might be surprising.

Physical appearance seems to be only part of the equation. Despite the billions of dollars forked over every year for cosmetics and beautification procedures, looks aren't the whole kit and kaboodle. In fact, according to a 2008 study in the journal Vision Research, even a computer can be taught to recognize who is hot or not. So what else can real live humans bring to the table?

Do opulent Christmas displays in stores and frenzied ads make you feel overwhelmed, depressed, or psyched? The emotions you feel might be a clue to your “shopping personality” – a pattern of behavior that corresponds with how you act in the rest of your life.

Kent State University behavioral economist Paul Albanese has identified four types of shoppers – normal, neurotic, compulsive and psychotic – based on clinical descriptions of human behavior and personality development in the Diagnostic and Statistical Manual (DSM), the psychologist’s bible. In describing these shopping personalities in his 2002 book, The Personality Continuum and Consumer Behavior, Albanese draws on the so-called object-relations theory of psychoanalysis, which says humans seek satisfaction through their relationships with others.  

Attention, shoppers: If the cart you selected has a handle greased with Vaseline, you may be an unwitting participant in an undercover experiment.

Ditto if you find an envelope stuffed with cash hanging out of a mailbox.

More than 600 people unknowingly took part in a series of "field experiments" in Groningen in the Netherlands designed to test the "broken window" theory, which posits that bad behavior begets bad behavior. That is: if someone sees, say, graffiti scrawled on a building, he or she will be tempted to do the same or commit some other illegal or mischievous act.

A few weeks ago, I found out that my presence on Facebook can indicate just how narcissistic I am, thanks to a study in the October issue of Personality and Social Psychology Bulletin. But the results were far from definitive, and I am just too interested (in myself) to rest without a better answer.

So I was delighted to find out that there was another study on the matter in the same journal that took a different tack. In this study, psychologists tried to explain a paradox: "If the behaviors associated with narcissism are also associated with ineffective leadership, why then do narcissists so often rise to positions of leadership and power?"