Does evidence support Maslow's Hierarchy of Needs? Maslow's Heirarchy of Needs (shown below) is a popular concept and is often taught in basic psychology courses, and often less objectively taught in Business and Marketing courses.

A common problem with Maslow's Hierarchy is the difficulty of testing the theory and the ordering and definition of needs. 

The Wikipedia article and most general sources about the topic do not discuss experimental tests regarding the Hierarchy nor am I familiar with any despite the theory's popularity.

What research exists that investigates Maslow's Hierarchy directly?
Mahmoud A. Wahba, Lawrence G. Bridwell, Maslow reconsidered: A review of research on the need hierarchy theory (1976), or a free pdf scan here


Its abstract says:


  The uncritical acceptance of Maslow's need hierarchy theory despite the lack of empirical evidence is discussed and the need for a review of recent empirical evidence is emphasized. A review of ten factor-analytic and three ranking studies testing Maslow's theory showed only partial support for the concept of need hierarchy. A large number of cross-sectional studies showed no clear evidence for Maslow's deprivation/domination proposition except with regard to self-actualization. Longitudinal studies testing Maslow's gratification/activation proposition showed no support, and the limited support received from cross-sectional studies is questionable due to numerous measurement problems. The difficulties with testing the theory are discussed and the conceptual, methodological, and measurement problems of the studies reviewed are detailed. The implications of the findings and future directions for research are outlined.