When looking at toys as user interfaces for children, several new problems that are not present in computer applications emerge. The main difference is that everything that appears on a computer is behind the barrier of a screen, while with toys children can directly manipulate the interface. The direct manipulation aspect of toys is important because the interface must be pleasing to not only sight and sound, but also touch.
For toys, productivity is not a factor. Toys are for entertainment and perhaps learning purposes only. So the interface does not need to be efficient or easy to use. The interface for toys only needs to be intuitive. Toys need to be so intuitive that a child picking up the toy would not make any mistakes using it even when playing with it for the first time.
The different goals of designing for computer applications versus designing toys for children make the design problem interesting. Designing toys have traditionally been completely unrelated to computers, so any advance in combining toys with computing power is relatively new.
Toys as models
Toys that model existing characters from television shows or books must portray the same personality and mannerisms as the original characters. Children would come to expect that the toys they play with are accurate models of what they have seen on the television or read in books.
Any deviation from the original character that the toy is modeling can result in a child making a mistake in using the toy. Since toys are supposed to be fun and making mistakes is not fun but frustrating, it is best to model toys as closely as possible to their original counterparts. Children will expect certain distinctive features and interaction techniques that are present in the original character to also be present in the toy character.
The wording of speech that comes from the characters must also be taken seriously. Small children will learn a lot from the toys they play with. The speech the toys generate must fit the personality of the characters they model after, but also be easy to comprehend meaning from. The toy must teach the right ideals and social lessons because children will likely imitate what they hear from the toy.
Another important factor in designing toys is the age of the target audience. Different age groups have different levels of comprehension. Toddlers have limited comprehension of speech and writing, but can often imitate what they see. Older children can comprehend sentences communicating simple concepts and have a shorter attention span than adults. These major differences between children and adults must be taken into consideration when designing the interface of the toy.
Children have a shorter attention span than adults. That means everything that the toy does must be quick and to the point. Long sentence commands or reactions by the toy will likely be ignored by children. When designing a toy, short commands and feedback must be given. Commands must be no more than one action per command, or young children will likely lose interest before the command sequence is completed.
Furthermore, the hand-eye coordination of children is not as developed as that of adults. The toy should not move during input, or the child would not be able to press buttons or otherwise interact with the character. The movement of toys provides good and entertaining feedback, but care must be taken so when the child interacts with the interface the toy is not moving.
Usability testing is important for testing toys. The most useful tests are testing prototypes with real children. As mentioned earlier, mistakes children make with toys are bad. Mistakes arise when the toy is not as intuitive as it should be or when a functionality that was expected of the toy is not there. Mistakes can cause features of the toy to go unnoticed or make the child lose interest in the toy.
In testing a toy with real children it is useful to note what the child expected to happen when he or she did certain things. From the article by Strommen and Bergman, it appears that they learned a lot just from pondering why children reached for certain things first and what they expected to result from doing it. The initial interaction with the toy is crucial because if a child fails with a toy on the first try then the child will not likely continue to play with the toy.
Designing interfaces to toys involve much more than knowledge of computers and computer usability. Designing interfaces for toys require a lot of knowledge of child psychology and development. Most design literature currently available discuss the design of interfaces for adults, but children have different thought processes.
Many design elements like the use of icons, the design of text, and error messages are completely different when it comes to toys. Designers cannot count on the user being able to comprehend instructions or be paying attention when crucial feedback happens. Designers can only count on natural intuition.
Even if children can use a toy as it was intended to be used, the toy designer must also take into consideration the psychological impact of using the toy. Toys for young children must not induce any negative behavioral effects. Toys must always encourage children and help teach them acceptable social habits. So in a way, the toy designer must act as a child psychologist to produce a good toy for young children.
Strommen, Erik and Bergman, Eric (ed.). Interactive Toy Characters as Interfaces for Children. Information Appliances and Beyond. Morgan Kaufmann Publishers. New York, 2000. Chapter 9.