Using four-parameter item response theory to model human figure drawings

Abstract

This paper studied the application of an extended version of the Item Response Theory, the 4-parameter model (4PL), in the item analysis of Human Figure Drawing (HFD). HFD score drawing might serve as indicators of cognitive development. This model incorporates an upper asymptotic parameter (parameter d) admitting the possibility that children with high capacity have a probability less than 1 to draw a certain HFD detail (item). This is often observed in HFD. We performed IRT model three times using 1, 2 and 4 parameter models and compared their model fit indexes. The latent trait correlations estimated by these three models were very high (r=0.98), suggesting that children's abilities did not change substantially when using the 4-parameter model. It is pointed out a limitation in the correct way of modeling test item dimensionality considering that there is a hierarchical structure among items.