FARE VENDING MACHINE

This Fare Vending Machine Prototype was part of my assignments for the Human Computer Interaction course I took in Spring 2018. The challenge for the propotype was to evaluate the current interface and design a new interface that supports the various users and improves performance for infrequent passengers who will begin their ride at the Washington National Airport.

All information in this case is my own and does not necessarilyt reflect the views of my professor - Dr. Joi Moore.

PROJECT GOALS

The goals of this project were:

  1. To evaluate the interface of the “Fare Vending” machine at the Washington DC Metro station.

  2. To develop a prototype for a new interface design.

EVALUATION METHODS

The methods I used for this project were:

  • Hierarchical task analysis (HTA) diagram to break down what tasks the user has to complete to purchase a paper fare card for a specific destination.

  • Gestalts principles and cognitive load theory to justify issues for the then interface of the two types of vending machines.

ISSUES WITH THE USER INTERFACE DESIGN

  • Major issues with the vending machine were identified through the use of Gestalts principle and cognitive load theory:

  • Proximinity issue

  • Dissimilarity issue

  • Information overload issue

DESIGN RECOMMENDATIONS

Design recommendations were developed based on major identified issues and Nielsen's heuristics a more user-friendly, efficient, and usable interface. Below are some key design recommendations

  1. Items related to the same task should be placed in close proximity. Based on Gestalts proximity principle, items tend to be perceived to be one unified group in they are put close together. The end user might not miss any option or any sub-task and might save their time to purchase the tickets if items related to the same task are placed close together.

  2. The three section containing information about the three main tasks should be of the uniform shape. Based on Gestalts proximity principle, to help people know what distinct objects might be a single unit, then their shapes should be similar. The main interface can be divided into three parts with the same shape but possible different sizes depending the objects needed to be displayed in each section to help the end user know that which task each object or information belongs to.

  3. Information display should be minimal. According to Miller (1956), our working memory is capable of holding only about seven items or elements of information at a time and deal with two or three items of information simultaneously. Too much information display like the current interface can lead to information overload which can leave the end user confused and/or unable to make a decision. The new interface, therefore, should keep no more than seven items of information and for each task and/or sub-task, the end user has to process no more than three items of information at the same time.

  4. Information needed for the purchase performance should appear in a natural and logical order. According to Nielsen (1995), to make a system intuitive to use for the end user, the procedure to complete a task in the system should appear in the order which people might assume it should be.

  5. Error prevention should be integrated. According to Nielsen (1995), a well-designed system should have error prevention system to prevent the end user to make a wrong decision. In this case, the system should let the user who wishes to use the ticket only one time to insert the starting point and the destination of the trip and calculate the fare they have to pay for them. If the end user inserted more value or insufficient value for their fare, the system should send messages to let the end user know if they commit to the action.

  6. The end user should have freedom and control over the system. According to Nielsen (1995), a well-designed interface should let the user have choices over their action. In this case, the system interface should let the end user choose if they want to buy one-time use ticket or multiple trip tickets. If the end user chooses one-time use ticket, the system should let the end user choose the starting point and the destination of their trip and automatically calculate the fare for them.

PROTOTYPE

Minhpham_prototype-for-the-miniproject.pptx

USABILITY EVALUATION METHODS FOR THE NEW SYSTEM

The proposed methods to evaluation the usability of the new user interface design were the use of hierarchical task analysis in combination with observations. Observations will be used to collect data of (1) rate of performance, (2) performance path, (3) perceptions of end users to the system. In other words, observations will be used to answer the questions: How easy did the user complete the target task? What was the performance path like? and how did the end user perceive the system?

EXAMPLE OF THE TEXTUAL HTA AND OBSERVATION GUIDELINES

Vending machine_HTA and observation guidelines

REFERENCES

Miller, O. A. (1956). The magical number seven, plus or minus two: Some limits on our capacity

for processing information. Psychol. Rev. 63: 81-97

Nielsen, Jakob. (1995). 10 Usability Heuristics for User Interface Design. Retrieved on

03/16/2018 from https://www.nngroup.com/articles/ten-usability-heuristics/.