## 7 Experiment Design
### Test Videos  
For the user study, a total of 4 TED videos were utilized. The number was chosen to ensure that each user explores a different video for each of the experiment attempts. TED videos are chosen due to their general-purpose nature and appeal to a wider audience therefore it made the selection of experiment participants simpler as any person familiar with informational style videos such as TED was qualified. All sample videos belong to the same topic, namely \"Economic Inequality\". This topic was chosen due to the fact that none of the study participants had an educational background in economics. It is to ensure consistency in the experiment tasks [1,7].  
While TED presentation videos have a consistent structure [70] there can be slight variations. For example some presenters use visual aids while others prefer to talk without any slides. Similarly, some presentation ends with a supplementary item such as an interview etc., while others only consist of a presentation. The sample video was chosen to be representative of the general TED video collections. Two of the TED videos used contain visual aid i.e., the presenters use slides and pictures in their presentation [69,71] while the other two presenters do not use any visual aid [72,73]. The reason for choosing two videos with slides and the other two without slides follows the idea of content value of different modalities (Section 1.1). For example in the video ED [71], the presenter speaks about mumps causing deaths in NY. She never tells the listener about the total number but a slide in her presentation shows the number. Now a question related to this can only be answered by utilizing the visual modality. Listening to audio-only or running a text search on the transcript of the presentation would not yield the answer. In the researcher's opinion, videos without visual aid were relatively easier to comprehend than the other two.  
In TED presentations, the presenter often presents the main idea of the presentation at the beginning of the video as in [PERSON]'s presentation [73], the presenter gives the main idea of the presentation early on and gives some details to reiterate it. This makes it easier for users to get the overall synopsis because users can still get the main idea of the video even if they did not consume all the portions. Whereas [PERSON] and [PERSON] [71,72] describe a problem and then offer a solution later and summarize the discussion in the end. Therefore, users are more likely to miss the essence of the presentation if they do not consume all the portions compared to the first video. The 4 th video [69] is an interesting case. While the presenter does give the main idea in the beginning, the technical nature of it makes it difficult for viewers to fully get the point, especially if the viewer does not have an economics background, it is only by watching the middle and the end parts of it that a viewer can get the essence, making it a relatively difficult video to comprehend.  
By choosing videos with and without visual aid and easy and difficult videos, the exploration experience of users with different types of content can be evaluated.