We often assume that the mapping between words and their meanings is completely arbitrary. Maurer et al. (2006) tested whether this was completely true. College students were shown the following two shapes, and asked to say which was “bouba” and which was “kiki.”

Eighteen of 20 students called the angular shape on the left kiki, while the other two called that shape bouba.

a. Calculate a confidence interval for the proportion of the population of students who would call the left shape kiki and the other bouba.

b. Test whether kiki and bouba are used with equal probability in the student population.