A short "interview" will usually give all the information needed to identify the method. Right-brain learners like the big picture, like to imagine things, lose track of time, and tend to be artistic. Left brain-learners like minute details, are logical, conscious of time, and like things to be concrete.
People speak in terms of how they process information. Visual learners speak in terms they can see, auditory learners speak in terms they can hear, and kinesthetic learners speak in terms they can feel. A visual learner will use phrases such as "see what I mean?", "'beyond a shadow of a doubt," "eye to eye," "mental image" and "pretty as a picture." An auditory learner will use phrases such as "clear as a bell," "an earful," "loud and clear" and "purrs like a kitten." A kinesthetic learner will use phrases such as "all washed up," "get a load of this," "not following you" and "topsy-turvy."
Visual people tend to be meticulous about appearance. Clothing is neat and pressed, hair is in place. They move briskly, efficiently, and purposefully. This person likes to read things, rather than be read to. Penmanship is usually neat and tidy. Visual people are organized and tend to take up hobbies that are visual, as in photography, painting, reading, and movies.
Auditory people dress for mobility and speak with a rhythmic cadence. They tend to have a rhythmic, bouncy gait. This person might read aloud, or move lips when reading, and tends to speak better than write. Hobbies include music, dancing, and speaking.
The kinesthetic person likes comfort, and dresses accordingly. They tend to walk, breathe, and speak slowly. This person likes action, and will lean toward activities that require it. They prefer to communicate by touch, and like to hug. Preferred hobbies include sports, woodworking or mechanics, and gardening.
If, after dialogue and observation, learning method still cannot be determined, there are several VAK (Visual, Auditory, Kinesthetic) questionnaires that can be used. They are easy to find online by searching for "VAK." Try the quiz offered by Businessballs.com. There are also questionnaires to determine left-brain/right-brain tendencies. Try the quiz that can be found at the Intelliscript website.
With practice, it becomes easy to identify the learning method of adults. Once this information is acquired, it can be used to improve communication, to assign tasks in which certain learning styles will excel, to build more complete committees or groups, and to present information in a way every member of your audience will comprehend.