(eds M.C.S. Wopereis et al.) 311 than white rice in Kumasi (the second largest city in Ghana), but this is not true for other markets in the country (Sakurai et al., 2006). Nigerians generally prefer cooked rice of a ‘harder’ texture than consumers in neighbouring countries. Watanabe et al. (2002a,b, 2006) showed that many grain quality characteristics such as grain breakage, grain whiteness af...

self-determination theory (sdt) states that satisfaction of basic psychological needs, including the need for autonomy, competence and relatedness will lead to intrinsic motivation. this study examines the relationship between basic psychological needs and intrinsic motivation of iranian female students in mathematics. for this purpose, 382 students of five school responded to the scale of intr...

According to empirical evidence, extrinsic incentives often crowd out intrinsic motivation, thus reducing the effort choices of workers. This article presents a simple model illustrating how the introduction of monetary incentives causes a discontinuous reduction in worker effort as well as a reduction in worker motivation to act in the interest of a principal. The primary finding is that motiv...