Absence of hardly pursued updating in a running memory task

In a running memory span task, the participants are presented with a list of items (e.g. numbers or words) of an unknown length, because this length varies from trial to trial. In one variation of the procedure the participants must report a certain fixed number of items (e.g. four) from the end of the list. According to Morris and Jones (British Journal of Psychology, 81, 111-121, 1990), the recalled items must be updated in memory as the presentation of the list progresses. Ruiz, Elosúa and Lechuga (The Quarterly Journal of Experimental Psychology, 5, 887-905, 2005) noted that an active strategy implies an inhibition in memory of the final discarded items, and did not find results which supported this hypothesis. The aim of this study is to check whether or not participants adopt an active processing strategy in extreme conditions. Experiment 1 uses catch trials, which induce the participants not to discard the first items of the lists, and also short lists (of 4, 7, 8, 9 and 10 items); these could be considered optimal conditions for updating. However, it should also be pointed out that with an upper limit of 10 items per list, participants could try to memorise the whole list in most of the trials. One way to discourage this strategy is including lists well over span (e.g. 14-26 items). The purpose of Experiment 2 was to analyse the 10-item lists in two conditions: within a context of much longer lists (well over span) in most of the trials and within a context of shorter lists (data of Experiment 1). Results in both experiments, from the analysis of location errors, indicate that even in these conditions the participants do not seem to carry out the supposed active updating of the memory set.