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