Noor AL Jiboury (Onondaga Community College), Tatiana Tavares (UFPB), Alexandre Nóbrega (UFPB) One of the lessons learned in area of HCI (Human Computer Interaction) is that usability evaluation (to test if the interface is easy to use by users) should start early in design process.The early the problems are detected, the greater the chance that they will be fixed. Usually the test used at the end of design cycle, where making changes to the interface is difficult and require a lot of time and work [1]. Introduction A little bit about usability method in practices method in practices We want to say thanks to... A study case about user interfaces evaluation for LIBRAS Language LIBRAS? What? Usability is an important condition for the design to be used by wide rang of people. Where its defined by its five quality components. Which are: learnability (how easy is to doing the basic tasks), efficiency (how fast the user can do the tasks after learning the design), memorability (if the design is usable after not using it for period of time), error (how many errors the user make, how several are these errors, and how easy they can recover from the error) and satisfaction (what the test users think about the design) [2]. LIBRAS is the name of the Brazilian Sign Language where it used by the majority of deaf people in Brazil. LAVID lab want to help this majority of people to be able to understand what's on TV, so they started developing new ideas of how to help them. Creating the Second window interface for LIBRAS Legend in digital Movies was their move to help. This design will give the deaf people in Brazil a great chance of watching and understanding any video they want. The design had two different parts, these parts are: 1. LIBRAS Dictionary, will translate words into signs. Where each sign is represented by an animated image or video file that has a code associated to it. 2. LIBRAS Generator, receives the input streams of audio, video, or closed caption from video encoder or closed caption generator. Directions will be given to the users using the LIBRAS language with Portages subtitle. Where it first will be asking the user to upload a video, then chose where we want the avatar window to be, finally we will chose the size of the avatar window. To make sure that the program is working in the right way we will be performing a usability test with the help of deaf people. For this application, the method called cognitive walkthrough approach will be used to evaluate the interface. Which analyses a specific sequence of steps; when an action is required by the user to accomplish a task. A group of users will test the interface by going through a group of tasks to evaluate the understandability and all of the five quality component. We will let the test users test the product and they will tell about their experience with the software, what's good and bad and what to fix and add. Where it involves a step by step task testing and a complete and detailed description of prototype, tasks and list of actions [3]. We ran three different groups of testing for each interface. The first group had three test users the second group had two test users and the third group had three test users. We followed this way of testing because it is better to distribute the budget for the user testing across many small tests because we want to improve the design not documents its weaknesses, the first group of testers will help us to solve 85% of the problems, the second group of users will help us with 15% of problems that was not found on the first test, finally, the third group will help us to find the last 2% of problems that may be left[4]. Where we evaluated all of the four tasks 1.Upload video file 2.Upload subtitle file 3.Determining avatar window position 4.Determining avatar window size After doing the tasks, users had to go through evaluation form. After reviewing the evaluation forms that the testers filled we came up with the following: 1.Puss button, so users do not have to start all over when they miss part of the direction video. 2.To be able to skip the directions, if the user is familiar with the design, where it's better to let them skip that part instead of wasting their time. 3.Let the directions on the buttons visible to the eye, by using simple language. 4.Display conformation button on the video window, because it will be easy to notice and know what the next step is. 5.Make the avatar movement faster, so the avatar would correspond to the actors actions. Figure 02: (a) LIBRAS - Brazilian Sign Language. (b) CineLibras – Brazilian application for deaf people. (c) CineLibras virtual interpreter. (a) (b) (c) Figure 03: The test users and the application. Figure 01: Usability. URL: yTest.png (a) (b) (c) Result References: 1."Usability Evaluation with the Cognitive Walkthrough" by John Rieman, Marita Franzke, and David Redmiles. 2."Introduction to Usability" by Jakob Nielsen. 3."introduction to Cognitive Walkthrough" by Emma Tonkin. 4."Why You Only Need To Test With 5 Users" by Jakob Nielsen