Programmer Musings

Why Graphical User Interfaces are Better than Textual User Interfaces

As I said in the last entry, you can separate computer users by their user interface preferences. In that entry, I made the argument that a text-based interface (TUI) is better than a graphical interface (GUI).

Since that isn't inflammatory enough, I'm now going to argue that GUIs are better than TUIs.

A Short History of Modern Computer Interfaces

Early computer interfaces were text-based because the computers were not powerful enough to draw much in the way of graphics while doing any other work. Also, we only had one real input device, the keyboard. Driving graphics with a keyboard is incredibly slow and awkward.

Once computers became fast enough to do the graphics calculations, Palo Alto's mouse became a viable way to interact with the computer. (Light-pen technologies were in use before the mouse, but they never got the kind of traction needed to take off.)

Attributes of Graphical Interfaces

GUIs have many advantages, including

• precise
• discoverable
• novice friendly
• small number of commands/gestures
• consistent set of commands for all objects
• well suited to touch interfaces

Some of these advantages explain why GUIs are usually regarded as user friendly. Most GUIs also have some disadvantages, including

• limited number of mouse commands/gestures
• not voice-input friendly
• hard to repeat commands
• expert hostile

Why Graphics?

The graphical interface made remembering objects, the nouns of the system, easier by representing each with a picture. New users could easily find the objects that they wanted to manipulate by just looking at the screen.

Although the mouse was originally limited to click, double-click, and dragging, system designers found ways to expand the use of the mouse without requiring the user to count clicks or do weird gestures. First, the modifier keys were added so that Shift-Click and Ctrl-Click could be different than a simple click. The development of the context menu, made it possible for different objects to have different possible commands without an explosion of mouse gestures.

Context

One spot where GUIs can cause some confusion is in the use of context. Different commands or mouse gestures can have very different effect depending on the current focus.

• Clicking on a picture may display it.
• Clicking a file may load your spreadsheet program.
• Clicking on a link may start your browser.
• Clicking on a program may execute it.

In each of these cases, you could argue that clicking on the object should do the default action for that thing, but until you learn the default actions this behaviour can be surprising. It does still cause problems when the thing you just clicked isn't what you thought it was.

The Killer Feature

The real killer feature of the GUI is the ability to boil down complex tasks and information into simple commands and displays. GUI-based tools make graphing data much easier than looking at rows of text. The web really took off when graphics and video became easier.

Drawing with a GUI interface is much more user friendly than trying to describe what you want to draw in text. As they say: A picture is worth a thousand words.

Comparison to TUIs

Unlike a TUI, you don't have to know the names of things advance to work on them. This makes the GUI initially much easier to use than a TUI. Moreover, a single (or double) mouse click normally does the right thing with the object. You don't need to learn a whole bunch of program names or commands in order to act on objects. With context menus, you can quickly find any other commands you might want to apply to an object, without a need for memorizing them.

In addition, there are many graphical tools that allow you to manipulate complex data in many forms by clicking and dragging exactly like you're used to. Some more complex actions may require new gestures, but they are normally not hard to learn.

Expanding Your Abilities

With a GUI, you can see large or complex sets of data all at once and work with them relatively easily. Selecting an area of a picture with a mouse is so much easier than trying to select it by typing commands. Scrolling with the mouse through a video or audio file is much easier than selecting a position with text, because of the instant feedback as you move.

GUIs kind of act as a magnifier on your normal abilities.