Does unitization really function like items? The role of interference on item and associative memory processes

Associative memory declines as we age, while item memory remains relatively stable. Previous work has shown that, in both younger and older adults, while item recognition declines linearly across time and interference, associative recognition declines only with longer delays and more interference. Unitization is a memory process found to support associative memory by allowing pairs to presumably be processed like single items. Research has found that unitization can benefit memory in aging by boosting associative memory to be on par with that of younger adults. Yet it remains unclear exactly the mechanism responsible for this enhancement in memory. The current studies aimed to determine whether unitized pairs show similar memory to that of items or associations with increasing time and interference, and determine how physically similar unitized pairs must be to perform like items and examine the effect of age on unitization in a continuous recognition paradigm. The results show that while unitized pairs exhibit higher corrected recognition compared with associative pairs at all lags, unitized pairs are not remembered to the degree that items are. It is critical that unitization boosts accurate recognition of pairs in both age groups across all early and middle lags compared with associative pairs. The results suggest that unitization may promote a more efficient associative link than unrelated associations over increasing time and interference, but the benefit does not reach that of item memory. These results demonstrate that while unitization benefits corrected recognition with earlier interference, its effect may not hold with later interference.