Based on the work of Unsworth, Heitz, Schrock and Engle (2005), a touch-based version of the automated Operation Span Task was created for iPad. Unfortunately in our current study, there wasn’t enough time to administer the task, but it is still functional.
Anyone wishing to use this, feel free to contact me for the source code.
Unsworth, N., Heitz, R. P., Schrock, J. C., & Engle, R. W. (2005). An automated version of the operation span task. Behavior Research Methods, 37(3), 498–505. http://doi.org/10.3758/BF03192720