Is "vignette study" natural English? What does it mean? A small-sized study?

Context:

ABSTRACT

The stigma of mental health treatment in the military may operate via the stereotype that soldiers
who seek treatment are weak. Perceptions of weakness derive from the belief that treatment
violates military norms of group cohesion and individualistic coping. This vignette study
examines the effects of group-centric motivation and a shared ingroup on weakness perceptions.
Results show no effect of the experimental variables on perceived weakness. However results
yield support for the hypothesis that contact with others who have sought treatment will reduce
stigma. Also, officers stereotyped treatment seekers as weak more than did junior enlisted
personnel.