Is perceptual salience needed in explanations of the isolation effect?

The isolation effect is a well-known phenomenon that has a well-accepted ex planation: An item that is isolated on a list becomes perceptually salient, which leads to extra rehearsal that enhances memory for the isolate. To ev aluate this hypothesis, the authors isolated an item near the beginning of a list. Immediately after each item was presented for study, participants j udged the likelihood of recalling the item. Although the isolation effect o ccurred, participants did not judge the isolate as being more memorable tha n the preceding item, suggesting that the isolate was not salient. In a sec ond experiment, participants rehearsed items aloud. Isolation at the beginn ing of the list did not produce extra rehearsal. By contrast, isolation in the middle of the list produced extra rehearsal; however, even when the iso late did not receive extra rehearsal, an isolation effect was evident. Thus , salience and extra rehearsal are not necessary for producing an isolation effect.