The effect of structure on scanning strategies

Ss heard four-digit strings and saw a two-digit probe immediately after each. Every possible combination of two digits taken from the string, as well as each member of the string combined with some digit from the negative set was tested. Reaction times for verifying that both probe digits occurred in the string reveal that Ss grouped the members of the string into two ordered pairs. This result argues that the structure Ss might assign to so-called random strings must be considered when discussing scanning strategies. Structural explanations of two common patterns of reaction times are presented.