Q. Happiness - who's got it, who's going to get it, who had it but lost it?

A. Of 16 nations surveyed, including 170,000 interviewees, the Danes, Swedes, Australians and Swiss rated themselves highest on happiness and life-satisfaction scales. The Greeks and Portuguese gave themselves the lowest marks; Canadians and Americans were somewhere in the middle. ("The Pursuit of Happiness," by David G. Myers, and other sources)* Those who are actively religious are more likely to report being happy.

* The old as a group are just as happy as the young.

* Within a given nation, the rich are only slightly happier than the poor. Some nations with lower per capita incomes such as Ireland rank higher on happiness scales than more affluent ones such as the U.S. or Japan.

* Those with college degrees are generally no happier than high-school dropouts.

* Based on studies of nearly 190,000 college students and adults in at least 39 countries, men and women are about equally happy.

* For all the jokes about the "state of holy matrimony," 39 percent of married adults report being "very happy" compared to 24 percent of never-marrieds and 12 percent of those divorced.

* Life changes - positive or negative - may breed great happiness or unhappiness; more stable conditions lead to an emotional status quo. Thus recent lottery winners feel elated but a year later are generally no happier than before. Accident victims who become paraplegics usually recover to nearly the same level of life satisfaction within a year or two.

In times of general economic upward mobility, the change feels good. But let the economy go into a slide and even if most people have more than they did 10 or 15 years before, they're apt to feel deprived and unhappy.

Q. Don't laugh, but do performing cockroaches "choke" before big audiences? (Coaches, take note.)

A. In an actual experiment, psychologist Robert Zajonc had roaches run simple or complex mazes, at times before clearly visible roach "spectators," at other times unobserved. Results: the roaches ran a simple straightline maze faster before onlookers, but a maze requiring a right turn to get to the goal took them longer before bugeyed crowds.

Conclusion: the presence of other roaches motivated subjects to better performance for the easy task but were a hindrance when things got tough.

And here's the payload: It's the same with people, says David G. Myers in "Social Psychology." The physiological arousal athletes feel in the presence of crowds - perspiration, faster breathing, tenser muscles - can lead them to run faster, shoot baskets better, hit a baseball more consistently. But only if they are highly skilled and well practiced.

Yet at times friendly fan arousal can run too high even for pros, as in the seventh game of the World Series. Now hometown players may succumb to a "championship choke," losing their homefield advantage, and like the roaches in the right-turn maze before an audience, they blow it.

Q. You know you can amuse yourself at the expense of your poor dog by tickling her belly and watching her "scratch reflex." Now answer this: If you tickle harder, will she scratch faster?

A. She'll scratch four or five times a second regardless, though the length and strength of each scratch will increase for harder tickles, says James Kalat in "Biological Psychology." The point is that this reflex is governed by the spinal cord and not peripheral sensory inputs.

Same story when she does a vigorous body shake to dry off after a plunge into water: Slow-motion video analyses reveal just about the same shake rate for all dogs.