The interest towards i-vis has increased over past years, specially in the field of HCI. I recently came across a research paper on i-vis by National Visualization and Analytics Center (USA). Though very scientific in nature this paper looks into how some of the ethnographic and performance techniques can be used evaluate the effectiveness of the i-vis.
http://nvac.pnl.gov/docs/RD_Agenda_NVAC_chapter6.pdf
Good read but requires patience 
http://www.nigelholmes.com/home.htm
Explanation Graphics at its best
http://www.visual-literacy.org/
Expectations regarding the methods and responsibilities of Designers and Researchers are changing. Ethnography has evolved as one of the major skill set for the designers to acquire.
AIGA, in collaboration with Cheskin, has produced a simple and straight-forward primer introducing the crucial role that ethnography plays in designing.
http://www.aiga.org/resources/content/3/7/4/5/documents/ethnography_primer.pdf
persuasion-and-visual-engagement.png
Content or “What is the message”:
The message is based on the positioning statement, the strategic approach and the evidence to support
your message. This is the traditional approach used for marketing writing and communications. Content
addresses the cerebral cortex of the brain. A reader learns new information; analyses and compares
information; makes decisions and stores the information.
Credibility of the message:
Readers filter messages depending on their perception of the credibility of the author or message. The
more credible the writer, the more information passes the filter to the cerebral cortex, where the message is analyzed, compared and so on. This absorption filter implies trust, which is an emotion. Hence, a message needs to go through the limbic system to be treated in the cerebral cortex.
Credibility of the message is fundamental for persuasion. Messages that seem to mislead
will close the absorption filter for an extended period of time. Hence, credibility implies that the message must be truthful and straight forward.
Emotional Involvement of the Viewer:
To be persuasive, a message has to go through the limbic system. As we have seen, trust is the
gatekeeper for information passed to the cerebral cortex. Emotions tell the reader when to pay
attention. Furthermore, emotions are processed faster than logical thought and have the final say in
moments of indecision. To be persuasive, the message MUST stimulate an emotional reaction from
the reader.
Welcome to Visual Semantics! A blog dedicated towards understanding persuasive power of visual design.
