The article outlines the general and somewhat self-evident paradigm that tasks which are mentally and physically more arduous and involved than simplified ones are less likely to be completed successfully or with more errors and vice versa (Lidwell, Holden & Butler, 2003). It goes on to describe that this is termed ‘performance load’ which is comprised of ‘cognitive load’ and ‘kinetic load’ (Miller, 1956; Sweller, 1988; Zipf, 1949). As the names suggest, cognitive refers to the mental aspect of a task and kinetic to the physical. They assert that by reducing the amount of mental activity in ways such that less retention and problem solving are required along with reducing the number of physical steps and their difficulty is the avenue down which design should be travelling (Lidwell et al., 2003). Essentially, the lower the production load (cognitive and physical), the higher the likelihood of a successful completion of whatever the designated task may be.
Lidwell, W., Holden, K. & Butler, J. (2003). Performance Load. In Universal Principles of Design (pp. 148-149). Beverly, Massachusetts: Rockport
Miller, G, A. (1956). The magical number seven plus or minus two: Some limits on our capacity for processing information. Psychological Review, 63(2), 81-97.
Sweller, J. (1988). Cognitive load during problem solving: Effects on learning. Cognitive Science, 12(2), 257-285. doi:10.1207/s15516709cog1202_4
Zipf, G, K. (1949). Human behavior and the principle of least effort. Boston, Massachusetts: Addison-Wesley [2016 reprint]