B.F. Skinner at the Harvard Psychology Department, circa 1950
<a href="//commons.wikimedia.org/wiki/User:Silly_rabbit" title="User:Silly rabbit">Silly rabbit</a>
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self-made (by <a href="//commons.wikimedia.org/wiki/User:Silly_rabbit" title="User:Silly rabbit">User:Silly rabbit</a>).  Updated in the Gimp by <a href="//commons.wikimedia.org/w/index.php?title=User:Michaelrayw2&amp;action=edit&amp;redlink=1" class="new" title="User:Michaelrayw2 (page does not exist)">User:Michaelrayw2</a>.