I heard this article on NPR this morning that talked about an experiment in which one group was presented with a picture of a child in need and another group was presented with a picture plus data about the global need. The objective was to prove that picture+data resulted in a more generous response.
The surprising result was that picture+data actually resulted in a less generous response from the peeps.
The first hypothesis was that this occurred because the picture alone elicited an emotional response, while the picture+data balanced emotion with logic, reducing the emotional response of charity (you know, left brain v. right brain).
However, what they believe occurred was that the picture+data peeps actually had conflicting emotions: the picture made them feel compassionate, but the data made them feel hopeless. The additional data made the problem feel so big that there was no sense that involvement could make an impact
I think the lesson learned is this: when presenting data, make sure you also enable people to feel like they can have a positive impact if they expend energy acting on what they see. In other words (once again), "carefully selected and action-oriented data" trumps "more data" every time.