Chang, B.W., Ungar, D., (1993). Animation: From Cartoons to the User Interface In Proceedings of User Interface and Software Technology (UIST 93) ACM Press, pp. 45-55.

By Chang Ha Lee

Visual changes in the user interfaces are often sudden and unexpected, surprising users and forcing them to step away from their task in order to grapple with understanding what is happening in the interface itself. The main goal of their work is to solve these problems and make the interface easier to understand and more pleasant to use. To do this The authors of this paper applied the principles of cartoon animation to the user interface. They mentioned following three principles of cartoon animation. The purpose of these principles is to make it easier for the user to track objects and understand what is changing on the screen.

• Solidity : Objects move and react as if they are real things.
  - Objects are drawn and move solidly
  - When objects are moved, motion blur fills in the gaps between the old and new position of the object
  - Objects are smoothly appeared and disappeared
  - Objects dissolve through one another as they change their layering
• Exaggeration : Exaggeration increases the prominence of significant features and call more attention to the object or the action
  - Major actions of objects can be anticipated with a quick contrary motion
• Reinforcement : By reinforcing the illusion of reality , keep the audience engaged with the interface.
  - slow in and slow out : objects move slowly at the beginning and ending of the movement and move faster during the middle of the movement
  - Objects move along arcs when they are moving non-interactively.
  - Follow through : objects coming to stop wiggle at the end of their motion

They employed the cartoon animation because of three characteristics of cartoon animation. First, cartoons are theatrical. So, it is suitable for communicating clearly and concisely. Second, cartoons are engaging. So, the user's attention may be devoted entirely to the task. Finally, the medium of cartoon is like that of graphics on the computer. But there are some differences. the cartoon is a passive medium for enjoyment and the user interface is interactive one for doing some task. So, in the user interface, the user's desires are important and animation should be fast enough.
To implement, They used 8-bit colormap divided into four parts: a 3-bit stationary layer, a 3-bit moving layer, and two1-bit arrow layers.
Some user test was carried out and there are two groups of users those who noticed the use of animation and are delighted and those who take the animation for granted from the start.

• Applying the principles of cartoon animation is very interesting idea and some of them are generally used today.
• Test methods are not described. I am not sure if there is a comparison with unanimated interface
• In the windows system, the object moved solidly is flickering even on the latest computer, so I prefer dragging the outline

1. There are two arrow layers for drawing arrows. Why arrows are treated as a special case?
2. The benefits of cartoon animation they mentioned are cognitive and affective. Can the techniques of cartoon animation improve the performance?