In a comparison of the linguistic results of Experiments I, II, and III, it will be important to have a measure of the relative difficulty of the learning under each of these three sets of conditions. In Experiments I and II, where the two visual factors of shape and color are exactly correlated with specific and uniformly recurring sound-sequences, it is also possible to compare the rates and degrees of learning of (1) the syllables corresponding to shape and color, and (2) the names corresponding to the 14 figures of the learning series and those corresponding to the 2 figures which occurred only in the recognition series. By correct response is meant a response to a figure substantially identical with the name which was taught to the subject in the learning series, or, in the case of the two figures which did not occur in the learning series, a response showing a correct analysis of the factors of shape and color in accordance with the categories of the linguistic system of the experiment. Many responses have been counted as correct, for the purposes of these comparisons, which deviate phonetically to some extent from the words taught, but which are nevertheless unmistakeable variants of these words.