Experience sampling method

This research methodology, developed by Larson and Csikszentmihalyi (1983) [Larson, R., & Csikszentmihalyi, M. (1983). The experience sampling method. "New Directions for Methodology of Social and Behavioral Science", 15, 41-56. ] asks participants to stop at certain times and make notes of their experience in real time. The point is for them to record temporal things like feelings while in the moment (right then, not later; right there, not elsewhere). They can be given a journal with many identical pages. Each page can have a psychometric scale, open questions, or anything else used to assess their condition in that place and time.

There are different ways to signal participants when to take notes in their journal, like using preprogrammed stopwatches. An observer can have an identically programmed stopwatch (the Timex Data Link USB is easy to program for this with a PC), so the observer can record specific events as the participants are recording their feelings or other behaviors. It is best to avoid letting subjects know in advance when they will record their feelings, so they can't anticipate the event, and will just be "acting naturally" when they stop and take notes on their current condition.

Validity in these studies comes from repetition, so you can look for patterns like participants reporting greater happiness right after meals. These correlations can then be tested by other means for cause and effect, since ESM just shows correlation.

Reference

Larson, R., & Csikszentmihalyi, M. (1983). The experience sampling method. New Directions for Methodology of Social and Behavioral Science, 15, 41-56.