[3] As computer systems at the time were widely regarded as difficult to learn and use, mainstream information processing theories and models in psychology were used as a basis from which to develop design principles, methods, analytic tools and prescriptive advice for the design of computer interfaces.
[4] Carroll writes that at the time, the 50 year struggle to establish psychology as a science was an important factor in trying to apply the scientific method to HCI studies.
Through the 1970s, the typical measures used by empirical studies for HCI were relatively simple; error frequencies and performance times such as by using or testing Fitt's law.
It was not well understood at the time, how to use structured programming to make higher code quality that is more reliable and maintainable.
Bardzell considers principles including equity, diversity, social justice, and the already existing theories on gender HCI.