Blind FLM Calculator is an open source simple calculator for mobile application prototyping for Blind people. It automatically evaluates your design with a predictive human performance model.
To use Blind FLM, create a storyboard of your mobile application design idea with images, buttons, etc. next, demonstrate tasks on that storyboard, then press "calculate" button to produce a valid model predicting how long it will take a skilled blind user to complete those tasks. Blind FLM can be used today to baseline your current mobile interface, or compare competitors' interfaces, and predict how much better your new designs will be.
GOMS model is cognitive modeling technique that is used to predict user’s performance with a system. KLM model is the simplest version of GOMS models. It predicts the execution time that an expert user needs to complete a system task. Recently, with the development of mobile technologies GOMS models have been extended. However, available enhancements of GOMS models including KLM model target normal users rather than Visually Impaired (VI) users. In this project, a mobile version of KLM model was analyzed and enhanced to support VI interactions with mobile phone applications. Therefore, three instruments (screening questionnaire, structured interview and observations) were used to analyze blinds mobile interactions. Each instrument provided different information about their interactions.
According to the instruments results, the KLM model was enhanced by retaining suitable operators, removing one operator and introducing a new operator to support blinds mobile interaction. An evaluation experiment was designed to evaluate the proposed enhanced model. We named the enhanced model Blind FLM. The experiment included two user studies each one served a different goal, and it involved three scenarios of the three top used applications in blind users’ community (WhatsApp, YouTube and Twitter). Twenty participants were involved to find the actual execution time of the three selected applications. Then, the model predictions were compared to the actual execution times to calculate the model’s prediction error. Root Mean Square Error (RMSE) was used to calculate the prediction error. The predicted error of Blind FLM model ranged from 1.27 to 3.81 percent with an average rate equals to 2.36, which is an acceptable prediction error. Finally, Blind FLM was implemented as a simple calculator (Blind FLM Calculator) to facilitate the model calculations process for mobile phone application designers and usability experts
1) Input textbox where all entered operators are entered.
2) Operators’ buttons grid which consists of the operators’ buttons (Tap (T), Flick (F), Mental (M), Double Tap (D), and Slide (S)) and Delete (Del) button to delete the input textbox and the output box from the previous result. Note: whenever the cursor hovers on a button, the buttons operator’s name is shown in a tooltip.
3) This checkbox provides the designer a choice to remove the burden of initial insertion of mental operators based on heuristic Rule 0. When it is checked the Mental (M) button is disabled and the mental operators are inserted automatically to operators’ sequence. Then the designer can remove unnecessary mental operators manually according to heuristic Rule 2. The manual application of R2 is important because removing unnecessary Mental (M) operators depends on cognitive unit determination. Since it can be only defined based on designer perspective.
4) Output textbox prints the predicted execution time in seconds.
5) Calculate button sends the command to the calculator to build the model and calculate the predicted execution time.
This project is Submitted in Accordance with the Requirements for the Degree of M.Sc. Information Technology, CCIS, KSU
Ideation and Supervision: Prof. Hend Al-Khalifa
Development: Wejdan Al-Tammimi
Special thanks goes to Dr.Shiroq Al-Megren for her support in the second part of the project.