Read about Don Norman's work on Emotional Design Here
Designs which tap into the user’s emotions are considered to do more than just respond to their needs and provide a greater level of user experience. Plutchik’s Wheel of Emotions can be used to understand some of the central key points to emotional design.
Robert Plutchik (21 October 1927 – 29 April 2006)
Author/Copyright holder: Machine Elf 1735. Copyright terms and license: Public Domain.
From the Interaction Design Foundation. Copyright terms and license. Public Domain. https://www.interaction-design.org/literature/topics/emotional-design
Follow Up Reading:
Emotional metrics for design at Smashing Magazine - http://www.smashingmagazine.com/2011/05/optimizing-emotional-engagement-in-web-design-through-metrics/
UX Review looks at emotional mapping for design here - http://theuxreview.co.uk/driving-more-valuable-customer-journeys-with-emotion-mapping-part-1/