Fig. 4.

The two flankers, similar and dissimilar, used with each target in Experiment 1. These are for observer J.F., based on his confusion matrix (Fig. 3). Lists for the other observers were much like these. The list was constructed by choosing flankers that were as similar (or dissimilar) to each target while satisfying the requirements that all 26 similar flankers should be unique (no repeats), all 26 dissimilar flankers should be unique, and pairs of targets (e.g., A and G) should share the same pair of flankers (e.g., N and C), similar-and-dissimilar for one target versus dissimilar-and-similar for the other target. Thus, each flanker pair—for example, N and C—was equally likely to be similar-and-dissimilar as dissimilar-and-similar. This symmetrical distribution of the flankersmade the joint distribution of the two flankers independent of the similarity of the flankers to the target. On each trial, the target was randomly selected (A–Z) and displayed between the similar and dissimilar flankers specified here, placed randomly left and right or right and left of the target. Thus, on each trial, each of the three letters could be any letter A–Z with equal probability