A systematic re-examination of the list-length effect in recognition memory

The list-length effect has been crucial in understanding the sources of forgetting in recognition memory, especially whether forgetting stems from interference generated by other items in the study list. However, there has been inconsistent evidence for the effect, and recent studies have found various confounds in the experimental design. The current study re-examined the list-length effect by controlling confounds that have been reported. We also systematically manipulated various factors such as the list length, study time, delay, and stimulus type, and tested a large sample to examine the robustness of the effect (i.e., radical randomization). Results showed evidence for a list-length effect across the conditions, and we find that the square root function best describes the list-length effect. By utilizing a computational model we also show that although the list-length effect exists, there is, in general, a greater amount of interference stemming from other sources in recognition memory (e.g., previous contexts).