Detection of informational constraints related to multi-variate visual displays

A contingent uncertainty of one bit is perceptible when imposed upon a combination of two binary-coded visual display variables, but not when imposed upon a combination of three variables. Why? The limitation may be sought in the average amount of the constraint, in the form of the constraint, or in the particular selection of display variables. Tests were carried out in which apparently equivalent informational constraints were imposed upon a single display variable. Such constraints were highly discriminable. Further tests reveal that the limiting feature for the detection of multi-variate constraints is probably the mean constraint level, averaged over all display elements, rather than the constraint level imposed upon the constrained display elements.