As a leader of the "qualitative" school of motivational research, [Ernest Dichter] believes that the real reason people buy one product over another is often a deep-seated emotion. Psyche in depth will reveal it, he thinks.

Why do big doorknobs help sell a house? Why do some men become irrationally hostile when their sock drawers are empty? Such are the questions that intrigue researchers like Mr. Dichter...

in the past two or three years Du Pont, Alcoa, General Mills, Procter & Gamble, Colgate-Palmolive, Johnson & Johnson, Schenley Industries and dozens of other well-known companies have commissioned studies from Mr. Dichter's Institute for Motivational Research here. The institute has annual volume of $600,000 and profits of $80,000 to $100,000.

Many people find Dichter's interpretations far-fetched. But people who accept the basic beliefs of modern psychologists find them quite plausible.

The psychologist says he's found that even a commonplace object like a doorknob has a surprising emotional significance to buyers.

"The doorknob offers the only way you can caress a house; you can't caress the walls," he says. "The way a product fills a hand is very important. How a handle does this will make an engineer prefer one technical product over another — and he doesn't even realize it," Mr. Dichter says.

During part of a baby's embryonic development, the thumb fills the palm of the hand, Mr. Dichter says. The new-born infant thus exhibits a strong desire to grasp objects, possibly to fill the palm of the hand again, the psychologist adds.

As he sees it, the same instinct later prompts a sub-conscious tendency to judge a house by its doorknob or a tool by its handle. Mr. Dichter says these findings and theories prompted a California lockmaker to enlarge the doorknobs it manufactured.

Even men's socks can inspire passion, Mr. Dichter asserts. "We find that an empty sock drawer is a symbol of an empty heart," Mr. Dichter said in a study for Du Pont's hosiery section. "When the husband finds that his sock drawer is not overflowing, he interprets his wife's neglect as symptomatic of her lack of consideration, concern and love."