“Usually women get blamed when a profession loses status, but in this case the trend started first, and men just evacuated,” said Dorothy Cantor, a former president of American Psychological Association who conducted a landmark study of gender and psychology in 1995. “Women moved up into the field and took their place.”

The impact of this gender switch on the value of therapy is negligible, studies suggest. A good therapist is a good therapist, male or female, and a mediocre one is a mediocre one. Shared experience may even be an impediment, in some cases: therapists often caution students against assuming that they have special insight into person’s problems just because they have something in common.

Still, perception is all important when it comes to seeking help for the very first time. In a recent study among 266 college men, Ronald F. Levant, a psychologist at the University of Akron, found that a man’s willingness to seek therapy was directly related to how strongly he agreed with traditionally male assumptions, like “I can usually handle whatever comes my way.” Such a man on the fence about seeking treatment could be discouraged by the prospect of talking to a woman.

“Many men like this believe that only another man can help them, and it doesn’t matter whether that’s true or not,” Dr. Levant said. “What’s important is what the client believes.”

Both male therapists and men who have been in treatment agree that there are certain topics that — at least initially, all things being equal — are best discussed within gender. Sex is one, they say. And some men are far less ashamed about affairs when speaking to another man.

Aggression is another. Many men grow up in a world of hostile body language and real physical violence that is almost entirely invisible to women. A bar fight that sounds traumatic to a female therapist may be no more than a good night out for a man. Likewise, a stare-down in the sandbox that looks vanishingly trivial from a distance may lie like a poisoned well in the stream of the unconscious.