recalls can reflect contextually mediated recall or other non-contextual processes, such as rehearsal of the first few or the last few items in a study list. Therefore, excluding lists that are likely to reflect significant rehearsal strategies may be crucial to uncover theta effects. The same study also observed a relation between theta power during retrieval with semantic distances between items, showing that increases in hippocampal theta power predicted greater clustering -- or contextual retrieval -- in semantic space [54]. Finally, a third study [13] asked subjects to retrieve the spatial location at which a cued item was presented, and compared more accurate to less accurate location retrievals, representing greater or lesser degrees of contextual reinstatement ([55] used a similar contrast to find mixed theta increases and decreases). Central to all of these studies was a comparison of “success to success,” with variability in neural processes relating solely to a specific measure of contextual reinstatement.
