June 2009
ISA Certified Automation Professional (CAP) program
Certified Automation Professionals (CAPs) are responsible for the direction, design, and deployment of systems and equipment for manufacturing and control systems.
The following question comes from the CAP study guide, Performance Domain IV, Development, Software development and coding
CAP question
When developing HMI (human-machine interface) screens, it is recommended the quantity of items an operator has to remember is less than:
A. 1
B. 3
C. 7
D. 20
CAP answer
The correct answer is C, 7.
Studies show people can remember approximately seven new things for about 20 seconds. This is short-term memory. After 20 seconds, people will have lost the information if they cannot quickly store it in long-term memory.
Reference: Susan Weinschenk, Pamela Jamar, Sarah C. Yeo; GUI Design Essentials; Wiley Computer Publishing, 1997
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