CONFRONTED BY the complicated food processor, the multi-purpose mixer with all its attachments and the variable speed blenders, it is difficult for the home cook to choose one over the other for use in an assortment of kitchen tasks.

The process of deciding can be greatly simplified by comparing the specific culinary functions performed by each piece of equipment with your own cooking habits.

A top quality food processor consists of a powerful and reliable motor set into a sturdy base. It should not bounce about the work surface while the unit is in operation. A drive shaft system connects the motor with a blade, which revolves within a clear plastic bowl. Safety requirements demand that food processors operate only while a lid is on the bowl. This has led to the design of various styles of feed tubes atop the cover, each of which attempts to direct the ingredients through the cover and into the blade at a proper angle. Some models have a stop/start mechanism limited to switches marked "on" and "off". Others have a "pulse" button, which puts the processor into operation for a few seconds, then turns it off a second, then back on, repeating this on-again-off-again cycle like a teen-age romance, so long as the pulse button is depressed.

Dozens of refinements have been made on food processors since their introduction to America in the late 1960s, but their basic functions are pretty much the same. Using a propeller shaped blade at the base of the processor bowl, you can chop, mince or puree just about every common ingredient. Drop in an onion that has been peeled and quartered and a few seconds later it will have been tearlessly minced. Pop in a few cooked chicken livers and before you can say "pate" it will be chopped. Fill the bowl with steamed broccoli and before your very eyes it is transformed effortlessly into a puree.

With this same basic blade, or one of its modifications, you can mix various ingredients together. A series of slicing and grating discs allows most ingredients to be cut into four or five different thicknesses and shapes or grate them into an equal number of forms. Thick or thin, fine or coarse, it's merely a matter of blade selection.Some processors have attachments that will cut food into a "julienne," or matchstick shape or cut potatoes into a "french fry" form. But essentially the primary functions of a food processor are mincing, chopping, pureeing, mixing, slicing and grating.

The big mixers, such as the KitchenAid K5A and K45 models or the Kenwood, are power centers to which an almost endless array of attachments can be added.

The best are beating, kneading, mixing and whipping attachments.These big mixers have large and powerful motors and their angle of attack allows them to knead larger quantities of bread dough more effectively than food procesors. tThe whisk attachments will whip more air into egg whites and heavy cream than any of the blades available with the processors. And they are superior to processsors in their ability to properly mix and beat large quantities of those ingredients associated with baking.

If you are a serious baker and must choose between the big mixers and the food processors, the mixer is the best bet.

The basic functions of these mixers have been greatly expanded by other attachments. They have optional units for grinding meat, stuffing sausages, slicing and grating, opening cans, extracting juices, milling grain, grinding coffee, peeling potatoes and even buffing silver. One company has an experimental attachment that is the best homemade pasta maker I have seen.

So the big mixer will beat, whip, knead and mix. They can, with additional equipment, grind, slice, grate, mill and juice. They will not, however, do a job at mincing, chopping or pureeing.

The blenders consist of a base unit which houses a motor and a container with a set of small, madly whirling blades at the bottom. They are spectacular at liquifying food, turning nuts to powders and mixing drinks. Blenders are perfect for most "bar functions" but be very careful when using them for pureeing and liquifying foods as part of a complex recipe. Their capacity is somewhat limited since the containers should not be filled much past two-thirds, which is no fun when you are making five quarts of vegetable puree for a soup.

To summarize: Food processors will do a fine job of mincing, chopping, pureeing, slicing and grating. They do an adequate job of mixing, beating, blending and small kneading jobs. Big mixers with their attachments will do a good job of grating, mixing and slicing. They will do a superior job of whipping, milling and dough kneading. They will not perform well at mincing, chopping or pureeing. Blenders have their greatest strengths at tasks that require pureeing and liquifying. The simpliest way to reach your decision is to make a list of the recipes you prepare more often with the essential function to the right, i.e. whole wheat bread -- kneading; vegetable soup -- pureeing. Then compare your list with the functions listed above with the three different machines. You will quickly see which will most adequately perform the desired task.