The washback (also known as backwash effect) is the influence that a test has on the way students are taught (e.g. the teaching mirrors the test because teachers want their students to pass).
It is the Students performance which reveals out the Teaching methodology, Nature of the materials,syllabus,curriculum and and also other factors that are related to the classroom atmosphere etc. All these examples creates an impact among the students' learning process which leads to the washback effect in the language testing.
Backwash effect in economics is a term coined by Prof. Gunnar Myrdal in his theory of Cumulative Circular Causation, according to which the development of one centre which is rich in resources, has better terms of trade and human capital tends to develop faster than the surrounding areas, thus leading to either positive or negative effects on the surrounding areas. The negative effects of center's expansion is that there will be outflow of capital from surrounding areas, out migration of human capital and also terms of trade will worsen. This shows that the opportunities of development in surrounding areas is washed back by the development of the center, therefore it is termed as the Backwash effect. Whereas the positive effect causes he growth of the surrounding areas due to the center's expansion, i.e. creation of secondary centres for expansion, thus developing the surrounding areas also. This is known as the Spread effect.
Edited By Sharon Grace S on 9/12/13