They are a people inhabiting Guinea and Liberia in West Africa

They are the Largest ethnic group in Liberia

The Origin of the River Niger is in their land

They came to international attention as a result of psychological tests on intelligence.

I understand that the following actually happened

Joe Glick, while studying the Kpelle tribe asked adults to sort items into categories. Rather than producing taxonomic categories (e.g. "fruit" for apple), they sorted into functional groups (e.g. "eat" for apple). Such functional grouping is something only very young children in Western culture would usually do. Glick tried and failed, to teach them to categorize items. Eventually he decided they simply didn't have the mental ability to categorize in this way.

This naturally led to the conclusion that they were not very bright

At some point he asked them how a stupid person would do this task.

It is reported that "At this point, without any hesitation, they sorted the items into taxonomic categories.

"They could do it, but in their culture, it was of no practical value. It was stupid"
http://research.kinasevych.ca/2010/02/glick-1975-cognitive-development-in-cross-cultural-perspective/

Check out this video

http://vimeo.com/49892461