Response bias in visual serial order memory

The recency-to-primacy shift represents a major challenge for all theories that attempt to explain the effects of serial order on memory. At short retention intervals, strong recency and no primacy effects occur, but as the retention interval increases, recency is attenuated and primacy increases. In 2 experiments, 24 participants were presented with sets of 4 unfamiliar faces and were asked to state the serial position of a probe face after 0 or 10 s. The predicted recency-to-primacy shift was obtained with accuracy responses. However, the distribution of responses also showed that there was a change in response bias with retention interval. When this was corrected for, the recency-to-primacy shift was eliminated. Response bias is suggested as the underlying cause of the recency-to-primacy shift in this task.