The history of hacking SIGMA: An autonomous and collaborative vocabulary learning system

In this paper, we recapitulate the history of hacking the SIGMA system, an autonomous and collaborative vocabulary learning system, over five years. The results obtained from various evaluation experiments have shown that (1) the vocabulary learning materials created by the SIGMA system are effective in enhancing vocabulary attainment; (2) the materials created not only by instructors but by the learners themselves are effective as learning tools; (3) the evaluation results that learners share in the system are actually helpful in allowing the users to select materials that enhance vocabulary learning.