Every Thanksgiving and Christmas when my family eats and gets together at my grandparents house, we like many other families have two separate tables. One for adults and the other for children. To the kids amusement my grandparents have these chairs that I like to call “screw stools”. Theses chairs operate like I describe them as, they screw up and down. The abnormal design of a chair works fairly well considering that it uses simple signifiers and mental models together for a user to understand how to adjust it.
This stool can be a good example of a system image. The system image stems from the designer’s conceptual model. This is the development of the look, feel, and operation according to the designer. In this example a the stool is what was made from the designer’s conceptual model. The actual system image (product or item) is the resulted from user’s interaction with the object. This is called the user’s conceptual model from interactions with the item. In this case the user or the kids in my family interact with it and develop their own conceptual model of the stool. A good design communicates the proper use of the object and the actual designer’s conceptual model. In my opinion the swirl spiral communicates and signifies a mental model of a screw. That the user can turn the top of chair to have it go higher or lower. This “screw stool” effectively communicates its system image and allows to adjust the height of the stool unlike usual stools that are just in one height.
This design is effect and not need for a redesign since the user can easily understand how to adjust the height of the stool. However, what if the user accidentally unscrews the seat portion of the stool. If this was the intention of the designer that it could be unscrewed out of the base. Yet, for a kid it might be hard to get it back on or screwed in again. A physical constraint should be put at the of the screwed seat preventing from being unscrewed out of the base.