How is the alphabet stored? Using priming to distinguish direct association from serial search
Alphabetic retrieval is a prototypical task that is studied to gain insight into how humans learn and process long lists. We shall study two conflicting models of this process: serial search and direct association. To distinguish between these models, we shall derive predictions about priming eects that occur when items are paired. In a new experiment, we measure these priming eects. Although the small data set does not allow strong conclusions, it shows that a pure associational model alone is too simplistic. How is the alphabet stored? How do people retrieve letters from the alphabet? Dierent accounts of how humans store and access the alphabet, or other long lists with little explicit structure, have been proposed. A good model must be able to explain human performance, and especially reaction times (RTs), in experimental tasks. Tasks that have been studied in experiments include: reciting the alphabet from a specific letter, saying the next letter, judging whether two letters are in the correct alpha- betic order, etc. All these experiments have found an increase in reaction times towards the end of the alphabet, as well as a distinctive pattern of peaks and valleys across the alphabet. In this paper we shall focus on this alphabetic retrieval task: A letter (the probe) is presented visually, and the subject has to say either the following or preceding letter in the alphabet. In the forward condition, the subject has to say the next letter in the alphabet. In the backward condition, the subject has to say the preceding letter. A pattern relating to this task is shown in Figure 1. Note how the location of peaks and valleys is consistent between the forward and backward tasks.