4. Discussion
The goal of this study was to investigate whether participants with developmental disabilities would benefit from playing a job-training serious game. To measure effectiveness, we tested whether playing two separate mini games of two individual tasks (apple packaging and hydroponics) affected hands-on task performance in terms of speed and accuracy. The results indicate that playing the matching game affected the target task performance speed. Such effects were witnessed in both apple packaging and hydroponics tasks. However, for performance accuracy, playing the matching game strongly affected the hydroponics task only; while the apple packaging task was not significantly affected. We suggest several possibilities why the Apple Packaging game yielded little effect on performance accuracy, while the effects of the Hydroponics game were strong. The discrepancy may have been due to the different levels of difficulty of the two tasks. In the national job curriculum for special schools, apple packaging is included in Chapter 2 Section 1, while hydroponics is included in Chapter 3 Section 4 (Korean Ministry of Education, Science, and Technology, 2010). The schoolcentred vocational curriculum tends to be hierarchical, with easier tasks that require basic skills appearing earlier in the curriculum and the more difficult tasks that require advanced skills appearing later in the curriculum (Korea National Institute of Special Education, 2005). Based on the asserted difficulty of the two tasks, one interpretation of the results may be that games are more effective for difficult tasks than for easy tasks when trying to achieve high accuracy. The second possibility is the ceiling effect, although this could be regarded a continuum of the first effect. We suspect that there was a ceiling effect for the apple packaging but not for the hydroponics task. Evidence that supports our speculation was found in the distribution of accuracy data at initial testing (Test Wave1). Accuracy scores with the highest frequency (48.9%) for apple packaging consisted of the total available points (14), which resulted in a J-shaped distribution, while for hydroponics, the highest frequency (53.2%) was at a lower score (12.9), which resulted in a bell-shaped distribution. Ceiling effects compromise statistical effects of the experimental data that ‘may lead to the mistaken conclusion that the independent variable has no effect’ (Cramer & Howitt, 2004, p. 21).
