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* Visibility: The different states of the interface is designated by highlighting and other visual signs. A certain tab will be "open" if that page is open, and a catergory item will be underlined and highlighted if that is what the user has selected. The visibility of the clickability of the thumbnails is lacking however. The overlay's visibility is improved by the "dimming" of the background.
* Efficiency: Having only thumbnails allows more streams to fit on a page, and picture recognition may be better than verbal recognition once the user becomes familiar with the thumbnails. However, if the user is not familiar, then the extra time needed to hover over thumbnails to get infocards would be a minus for efficiency. Also, the filmstrip idea is alright if the user is just browsing, but if there is a thing he saw early on that he wants to go back to, the filmstrip could be inefficient because it's like scrolling a scrollbar with the up/down buttons onlyThe efficiency of our interface is affected by the amount of data (i.e. collection of stream channels) that we have. The more channels, the more a user has to scroll to find a specific channel. We had a search feature and the recent history page to improve efficiency for experienced users. For new users, who are unsure of how channels are categorized, it may take some time to browse through all the categories. Overall, the main uses of SB are Catergories, Recent History, and Search, and it's very easy to navigate to them. The tabbed and thumbnail navigation should be familiar with many users.
* Errors: Errors are easily recovered from. There won't be any mode errors since there aren't different modes of operation. If the user clicks the wrong stream, all he has to do is go back on his browser. Similarly, other operations like searching and selecting a category are reversible by simply choosing the right thing after an error.
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