The Item/Order Account of Word Frequency Effects : Evidence from Serial Order Tests

According to the item/order hypothesis, high frequency words are processed efficiently and therefore order information can be readily encoded. In contrast, low frequency are processed less efficiently and the focus on item-specific processing compromises order information. However, most experiments testing this account use free recall, which has led to two major problems: First, the role of order information is difficult to evaluate in free recall and second, the data from free recall show all three possible patterns of results: memory for high frequency words can be better than that for low frequency words, can be worse, and can be equivalent. We report a series of experiments that test the item/order hypothesis using tests where the role of order information is less ambiguous than in free recall. The item/order hypothesis predicts better performance for high than low frequency words when pure lists are used in both immediate serial recall (ISR) and serial reconstruction of order (SRO) tests. In contrast, when mixed (alternating) lists are used, it predicts better performance for low than for high frequency words with ISR tests, but equivalent performance with SRO tests. The experiments generally confirm these predictions with the notable exception of a block order effect in SRO tasks: When a block of low frequency lists preceded a block of high frequency lists, a high-frequency advantage was observed but when a block of high frequency lists preceded a block of low frequency lists, no frequency effect was observed. A final experiment provides evidence that this block order effect is due to metacognitive factors.