As another performance measure, the NASA-TLX subjective workload assessment tool was applied, which derives an overall workload score based on a weighted average of ratings on six subscales: mental demand, physical demand, temporal demand, effort, performance, and frustration level. This measure is thought to be useful for an estimate of the attentional demands of a task, considering that demands are relevant to poor learning performance. Table 4 summarizes the data collected, together with the mean scores for the six workload items, respectively.