To date a small palette of isotrigon textures have been available to study how the brain uses higher-order spatial correlation information. We introduce several hundred new isotrigon textures. Special modulation properties are illustrated that can be used to extract neural responses to higher-order spatial correlations. We also ask how many textures make an adequate training set and how representative individual examples are of their texture class. Human discrimination of 90 of these patterns was quantified. Modeling those responses shows that humanlike performance can be obtained providing a fourth-order classifier is used, although more than one mechanism is required.
