and are not changing throughout the interface. A header, content and footer make the three layers
of the interface. The header is an important part which contains instructions for the customer.
The content section is well organized (Stone et al., 2005) with each element encapsulated in
different sections or tables which allows the user to distinguish between them. The footer
contains options that are useful for client like revers actions or cancel order. All the sections are
consistent and the first rule of Shneiderman (2010) is applied regarding these elements: color,
font, layout, capitalization. The font used is “Segoe Print” because allows the user to have an
easy reading of the information. Capitalization is used in order to point the important elements.
In terms of navigation the interaction between the user and machine is done through touching
the screen. The machine is a touch screen machine. The design offers large images and sections
that can be touched and redirects the user to the specific location. To navigate the client should
have visibility, the aspect that is point out by Stone et al. (2005) which states that this is the first
step to the goal. The design meets this requirement with a good organization with large gaps
between items and with no overcrowded items.
An aspect covered by Nielsen and Molich (1990) is flexibility and efficiency. The flexibility
of the design is shown by having more option to choose from for the payments, letting the
customer have more than once choice. Also the user can make changes the opinion involving
selecting new method of payment, selecting new products, removing products and canceling
order. The efficiency of the interface is done by having a good time for making an order. The
estimated time is between 4 and 7 minutes.
Also, Johnson (2007) speaks about the necessity of a good functionality, rather than a good
looking design. Because sometimes people make mistakes and perfection is never achieved, error
prevention is an element that is applied to the design (Nielsen and Molich, 1990). Error messages
are shown when customer is inserting insufficient amount of money or when there is insufficient
funds on card.