I don't know of published reports, but you may want to contact the education
department of the National Zoo, SI, in DC. I think they did a major study on
this back around 1987...I only remember it because I think we collected some
data for them as part of our museum education class at GWU--also Mt. Vernon
(GW's home), I think did a similar study around the same time.
Lisa Falk
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