Abstract
Pictorial discrimination experiments reveal something about the eye and the picture. Here, we focused on the picture and studied whether Number of Distinguishable Levels (NDLs) would depend on the time period in which the pictures were created. We were interested in a wide (but limited) variety of pictorial attributes: softness and glossiness of fabrics, facial expressions, pictorial convincingness and aesthetic appreciation. To maintain a relatively constant scene that is present throughout a large chunk of (western) art history, we chose for paintings of the Madonna, taken from the Materials in Paintings (MiP) database. In Experiment 1 we used four sets (each one century) of 12 paintings, in Experiment 2 we mixed all creation dates. We used an online Thurstonian scaling experiment where each painting of an N=12 set was pairwise compared with respect to glossiness, softness, convincingness, aesthetics and expression. Thus, each experiment comprised of 20 scaling experiments. The results of Experiment 1 revealed no systematic chronological trends. Also, averaging the five attributes did not reveal a trend. As expected, the NDLs increased when Thurstonian scaling experiments were performed on sets spanning all four centuries, demonstrating that across time we find more variety than within a fixed period. Furthermore, we correlated the scaling values with creation year. Especially in Experiment 2 we found many significant correlations. For example, Madonna’s robe is depicted more soft over time. Also, aesthetic pleasure and convincingness increase with time, and perhaps more interesting we found that facial expressions become stronger. In conclusion, the pictorial attributes themselves change substantially over time, but the variety (NDLs) stays rather constant. While the Madonna’s of art history all appear rather different, in terms of attribute variety they differ less then one may suspect, although they do change over time.