Q. Your nostrils and bronchial tubes just dilated, larynx and pharynx widened, diaphragm sank, tongue drifted back, heartbeat accelerated, tears and saliva welled while your jaw dropped and shimmied back and forth. Is there a doctor in the house?

A. Hold the call - you just yawned. And you're not the only one, says Temple University psychologist Ronald Baenninger:

- Fish, birds, reptiles and mammals all yawn, with carnivores doing it more than herbivores.

- Fetuses yawn, as do newborns usually within five minutes after birth.

- In actual experiments, people have found it next to impossible to yawn with their mouths taped shut!

- Athletes yawn before tense contests, as do college students in libraries, but neither can match calculus students, who by one count rack up 25 per hour.

- Some people who are paralyzed on one side of the body are able to stretch otherwise immobile limbs during a yawn.

Q. There's no barn alongside a certain road but you want to put one there - in a witness's memory. Got the trick?

A. Use leading questions, a technique well known to courtroom practitioners.

Memory expert Elizabeth Loftus showed test subjects a film of an auto accident, then asked half of them, "How fast was the white sports car going when it passed the barn while traveling along the country road?," and the other half, "How fast was the white sports car traveling along the country road?"

A week later she asked all the viewers if they had seen a barn. Actually, there had been no barn in the film. Now a good percentage of the "witnesses" who had heard mention of a barn stated they had seen one, compared to almost none of the others.

Also, cars can be speeded up and broken glass conjured with calculated phrasings: In another study, subjects viewed a film clip of an accident and now half were asked, "How fast were the cars going when they `hit' each other?," and the rest, "How fast were the cars going when they `smashed into' each other?"

Those hearing "smashed into" judged that the cars had been going faster, and many later were even willing to agree that there had been broken glass when there in fact was none.

Moral: Memory is malleable as well as slippery.

Q. What have to be two of the all-time worst disguises in the annals of crime and crime-fighting?

A. Superman's and Batman's. Start with the fact that each of us can distinguish thousands, maybe even tens of thousands of different faces, says John P. Dworetzky in "Psychology." Even identical twins won't fool you once you get to know them.

And people are such keen face-spotters - way beyond the current capabilities of any programmed computer - they can recognize an old friend they haven't seen in 20 years, in spite of wrinkles, sags, graying hair.

"In truth, Superman had no real hope of disguising himself from those who knew him by combing his hair slightly differently and putting on a pair of horn-rimmed glasses."

And even where the eye might get taken in, the ear probably won't.

"Together, the eyes and ears are formidable detectives. Even Bruce Wayne's friends meeting Batman for the first time would take one look at his mouth, hear his voice, and ask, `Bruce, why are you dressed as a bat?' "