volve the use of mnemonics and acronyms to prompt the user to recall additional detail. All of this involves work on the user's part. This can jeopardise the success of a user interface. As mentioned, it takes effort to hold things in short-term memory. We all experience a sense of relief when it is freed up. For example, you may have felt this when you finished reciting the remembered items in the previous exercise. As a result of the strain of maintaining short-term memory, users often hurry to finish some tasks. They want to experience the sense of when they achieve their objective, this is called closure: This haste can lead to error. The early cash dispensers suffered from this problem. Users experienced a sense of closure when they satisfied their objective of withdrawing money. They then walked away and left their cards in the machine. As a result cash will now not be dispensed until you take your card. An important aim for user interface design is to reduce the load on short-term memory. This can be done through cognition by recording information `in world' not `in the head'. This involves the use of prompts on the display and the provision of paper documentation. Hence the supplementation enables users to navigate their way correctly, hence the effectiveness of cognition.Perception involves the use of our senses to detect information. We have to make sure that people can see or hear displays if they are to use them. In some environments this causes huge problems. For instance, most aircraft produce over 15 audible warnings. It is relatively easy to confuse them under stress. Background noise can be over 100db. Although such observations may be worrying for the business traveller, what significance do they have for more general interactive design? Von Eckardt, B. (1993). What is Cognitive Science, argues that we must ensure that signals are redundant. If we display critical information by small changes to the screen then many pe...
