The satisfied user

We interpret human-system interaction as a sequence of information-processing operations. According to computational cognition (Newell, 1990; Simon & Kaplan, 1989) and computational vision (Marr, 1982), information processing should be studied at three different levels of abstraction, that is, at the knowledge level, at the level of algorithm, and at the level of implementation. Human-system interaction is analysed at these levels with an emphasis on user satisfaction and effective and efficient goal achievement. It is concluded that user satisfaction has more or less independent components at these levels, namely, satisfaction evoked by adequate subgoaling, adequate problem-solving strategy, and adequate implementation.