A moving paper ribbon, a one-way mirror, and hidden microphone figure in a new Social Relations scheme for finding out how people get along with each other.

Announcement of the new system was made last night by its inventor, Robert F. Bales, assistant professor of Sociology.

Bales incarcerates his subjects in a specially rigged conference room and tells them to conduct a meeting. But unknown to them, Bales and his minions are spying on them through a one-way mirror covering one wall.

The chamber is also equipped with a voice recorder so sensitive that it can pick up even the softest and most confidential whisper, and betray it to the concealed investigators.

But the key to Bales' espionage system is a device to be known as an "interaction recorder." The machine has a metal frame with 14 holes in it, one for each of 14 different kinds of "action."

Underneath the frame flows a ribbon of paper. Every time one of the subjects says something, a social worker marks the moving paper through the proper hole.

Others of the crew take notes on recalling details like yawning and table-tapping that can be seen around the conference table. When the experiment is over, the investigators draw up a "profile" of their guinea-pig meeting.

First they look at the marks on the long strip of paper, which are in the form of numbers. Each subject has been assigned a number, and an inscription like "3-1" means that subject one has talked to subject three.

Then to make their analysis, the sociologists look and see which of the 14 categories each action belongs to. Some of the 14 categories are: squelching an imminent misunderstanding, asking for facts, and sticking to the business of the meeting.

Others are finding out how to get some work done, agreeing, asking or giving help, wielding or bowing to authority, surrendering the floor, and practicing teamwork.

Bales has found that a graduate student well-grounded in sociology and psychology can learn to use the machine after two or three weeks of practice. During an experiment, "actions' 'have to be recorded about nine times a minute.

Although the new system hasn't been put into operation very much yet, Bales has already discovered some general principles about what people do when they get together for a meeting.

First a group explores the problem before it, arguing and getting more and more nervous. Sometimes someone will tell a joke and relieve the tension for a moment. After an agreement has finally been reached, there is a let-down, usually marked by joshing and small talk.

The person with the most prestige tends to do the most talking at a meeting and he often wins people to his side of an argument even if he is wrong.

By rearranging furniture, the experimenting chamber can be transformed from a conference room into an office or living room. Bales, as a matter of fact, is considering making studies of people who play bridge together.

Another type of machine for studying small groups of people is the "interaction chronograph" of Eliot D. Chapple '31, former professor of Anthropology.

Chapple's contraption measure the rate of "interaction" between two people, but can't recent the content of their remarks the way Bales' can.

Department stores have used Chapple's machine to see how efficient their clerks are.