then. There has been evidence evaluating and supporting this shortened version over the full one since it might increase experimental validity. When using the "raw TLX", individual subscales may be dropped if less relevant to the task. Administration The Official NASA-TLX can be administered using a paper and pencil version, or using the Official NASA TLX for Apple iOS App. There are also numerous unofficial computerized implementations of the NASA TLX. These unofficial versions may collect Personally Identifiable Information (PII), which is a violation of NASA Human Subject Research Guidelines for the Collection of PII as set down by the NASA Independent Review Board (IRB). If a participant is required to answer the TLX questions multiple times, they only need to answer the 15 pairwise comparisons once per task type. If a participant's workload needs to be measured for intrinsically different tasks, then revisiting the pairwise comparisons may be required. In every case, the subject should answer all 6 subjective rating subscales. It is these successive ratings that are then scored using the original pairwise questions as weighting factors, that leads to an understanding of the overall workload change. While there are multiple ways to administer the NASA-TLX, some may change the results of the test. One study showed that a paper-and-pencil version led to less cognitive workload than processing the information on a computer screen. However, other studies found that computer screen versions, as well as on wearables, can nonetheless stably capture relative changes in workload. To overcome the delay in administrating the test, the Official NASA TLX Apple iOS App can be used to capture both the pairwise question answers and a subjects subjective subscale input, as well as calculating the final weighted and unweighted results. A feature found in the Official NASA TLX App is a new computer interface response rating scale, termed a Subjective Analogue Equivalent Rating (SAER) scale, that provides the closest possible user experience to that found in the paper and pencil version of NASA TLX. No other computerized version of the NASA TLX has successfully implemented this critical element for properly capturing a user subjective input. This can be seen in many unofficial computerized (both web and software application) versions that use an anchored or locking scale. This defeats the subjective purpose of the original paper and pencil implementation of the NASA TLX. See also Cognitive load References External links Official NASA TLX