This from The Emotional Brain by Joseph LeDoux:
Often we are asked whether ZMET work with so-called unemotional participants. There is no such thing as a fully-functioning person who is unemotional. There may be, however, certain “display rules” that people abide by that make them appear unemotional.
LeDoux cites a study that compared people from Japan (which some believe to be an “unemotional” culture) with those of America. Groups of Japanese and Americans watched a short film filled with scenes meant to be emotion-arousing. The scenes ranged from highly positive (people who were experiencing joyful moments) to highly negative (images of people with graphic, disfiguring, wounds).
When watching with another person, Japanese participants, indeed, were more reserved than Americans and displayed less emotional diversity. But when watching alone, the range of emotional reactions was similar across both Americans and Japanese.
LeDoux theorizes that Japanese culture, generally speaking, tends to discourage outward displays of emotion. American culture, not so much. But below the surface, people from Japan are no more or less emotional than anyone else.
So when we’re confronted with individuals who appear to be stoic, or groups of people (like doctors) who often profess to make emotion-free decisions, we must keep in mind in the interviews and reinforce with our clients that the lack of emotion is a display, a way of presenting oneself to the world. It does not reflect a lack of emotional thought. Listening closely for metaphors (and playing with them in the interviews) will make those emotions bubble to the surface, even in the primmest, stuffiest, stone-face.