Abstract
Shape is considered the most important visual feature of objects but color can also aid in object recognition and naming. However, it is unclear how much color information is automatically encoded in visual long-term memory. What is the nature of color object memory? And if color is encoded in visual object memory, is it exact or categorical? We investigated these questions in 6 experiments with both color-diagnostic and non-color-diagnostic familiar objects and human faces. The experiments use a study task for object images followed by a perceptual 2-interval forced choice task between two shifted color versions of the same object image. Experiments 1 and 2 found a preference for shifted color images that stay within the original color category of a color-diagnostic object even if the color is more extreme. Experiment 2 found the same result as Experiment 1 without any study trials, which suggests color categories in object memory exist and that they are at least in part based on prior knowledge of object color. Experiments 3 and 4 demonstrated that color memory is influenced by both recent perceptual experience, such as the shifted color of a studied object, and by prior knowledge of the typical color of an object, which may be semantically mediated by object identity. Distance in color space was most important only when a color category boundary is crossed. Experiment 5 found evidence for categorical color memory for human faces and food, categories for which color is an important visual feature. Again categorical color memory seems to be strongest for these object classes, with some evidence for exact color memory. Experiment 6 found no evidence for exact or categorical color memory for non-color-diagnostic objects. Overall, we find that object color memory is categorical for objects for which color is an important diagnostic feature.