CONSUMER GROUPS will not be surprised, though they are certain to be disheartened, by the latest findings in the annual Food Marketing Institute survey. Only 27 percent of the public said they would join an organized consumer boycott against a particular product or store. Six and half years ago, when FMI, a trade association for the retail and wholesale food industry, began this annual survey of consumer attitudes, 38 percent of the respondents thought boycotting was useful.

If shoppers are somewhat disenchanted with the effectiveness of consumer groups, they are even more disenchanted with the effectiveness of their congressmen. Only 50 percent in the January 1981 survery, conducted by Lou Harris, would write a letter to their congressman demanding that the government do something. That's a low point in the history of the surveys. It was as high as 68 percent in 1974 when the surveys began.

People seem to be placing more faith in their own ability to get things done and less in the federal government and organizations, or are throwing up their hands and saying, "Why bother?" More of them are taking their complaints directly to the supermarket where they shop. More than 40 percent have complained to the manager directly; 57 percent returned products to the store for refund or exchange.

Jeffrey Prince, public relations director for FMI, thinks this finding is significant. "Generally people feel they will get an immediate response from the supermarket. They will not get an immediate response from the government or a consumer group. They feel supermarkets are more responsive."

Even though people won't turn to the government for help, fewer of them blame the government for high food prices. In July 1974, more than half the respondents laid the blame at the government's feet; in this latest survey the number is down to 34 percent. Supermarkets aren't getting the blame for high food prices, either. Only 4 percent of those surveyed blame supermarkets, and that's the lowest the figure has ever been.

But 60 percent of the respondents believe supermarkets don't give consumers good value for their dollar. The figure has been higher, and the supermarket industry takes heart from the fact that most other businesses fare worse. Only farmers have a positive image among a majority. On the other hand -- a fact that must confuse the supermarket industry -- most shoppers feel the stores in which they shop do a good job of providing certain services. f

And shoppers expect a lot from their supermarkets. By a significant majority, customers want them to have readable and accurate shelf tags, to provide cheaper house brands or generics, to help save money with specials, to help feed the family more nutritiously.

There are a number of other things shoppers think supermarkets should be doing, but, for the most part, aren't. A lot of shoppers would like stores to provide cautionary labels for allegedly unsafe products (79 percent); to refuse to carry allegedly unsafe products (73 percent); to provide nutrition and health information (61 percent). They don't like it when their supermarkets advertise products believed to be unsafe or to have a high health risk (69 percent) or when they change the prices of products on the shelves every few days as costs rise (74 percent).

On a subject of much concern in the Washington area -- computer-assisted checkout systems -- the majority or respondents either had positive feelings or were indifferent. The vast majority of supermarkets in this country do not have electronic scanners yet. Unfortunately, the survey did not ask the follow-up question on the mnds of Washington shoppers: "How do you feel about computer-assisted checkouts if they meant the elimination of individual price marking?"

Giant has eliminated individual price marking and reduced prices on a number of items in its stores. A local polling firm conducted a survey recently to see how the public is responding to this action.It uncovered some inexplicable reactions: A majority of people in the Maryland suburbs and the District are in favor of individual price removal as long as it means lower prices, but a majority of people in the Virginia suburbs are opposed to the idea.

Not surprisingly, saving money is uppermost in the minds of most people. More than ever, they are making use of coupons (76 percent, a figure that has been increasing steadily since 1974, when 66 percent of those surveyed used coupons.)

And, more than ever, shoppers are stocking up when they find a good bargain (79 percent) and buying products on special when they hadn't planned to. But they are not buying more store and lower-priced brands than they did last year or in 1974. The figures are down from 77 percent to 71 percent.

More of them, however, are making use of leftovers (79 percent, a figure that has continued a slow but steady rise in the last 6 1/2 years). More of them are baking, canning and freezing (56 percent) than ever before.

As inflation continues and a greater number of people are severely affected by it, they discover methods of coping that some people have been using for years: 23 percent have recently cut down on the number of luxury and snack items they buy; 21 percent have cut down on the amount of meat.

Even though almost three out of four shoppers believe food prices are rising more rapidly today than they were a year ago, the figure is well below last year's level. There is, as some see it, a new trouble on the horizon. For the first time since 1977 the majority of those surveyed think unemployment will become a more serious problem than rising prices.