University of Canterbury researcher Christoph Bartneck says the faces of LEGO Minifigures have gotten angrier looking over time. Bartneck asked a sampling of adults to categorize the emotions of the 3655 different types of minifigure faces produced by LEGO between 1975 and 2010. While 324 of the figures still featured happy expressions, 192 featured angry ones. Over time, the increase in angry faces has paralleled the rise of licensed themes in the LEGO lineup, whose characters often feature angrier expressions. While the effect of such angrier faces of LEGO minifigures has not been researched, researchers seemed concern about how children would interpret such expressions.