Collaborative memory for categorized lists: ongoing and lasting effects are sensitive to episodic memory tasks

Previous studies have confirmed that collaboration in memory can elicit reliable impairment (e.g. collaborative inhibition) and enhancement (e.g. error pruning and post-collaborative recall benefit). However, there is scarce research considering whether these phenomena would occur in semantically related stimuli, especially when in different episodic memory tasks. After encoding some exemplars of certain categories, participants were instructed to sequentially recall originally studied exemplars (item recall) and their encoding colors (source retrieval). The tests were performed twice (Recall 1 and Recall 2), with Recall 1 been done either individually or collaboratively, whereas Recall 2 was an individual test. We replicated the detrimental effect of collaborative inhibition, as well as two beneficial effects of error pruning and post-collaborative recall benefit. Besides, both collaborative inhibition and post-collaborative recall benefit were sensitive to episodic memory tasks; meanwhile, the indicators of both item-specific processing and relational processing were modulated by memory tasks. The novel implications are: (a) revealing that effects of collaborative memory are sensitive to memory tasks; (b) extending the occurrence of a beneficial effect of error pruning to categorized lists; as well as (c) demonstrating that collaboration can attenuate the item-specific processing but enhance the relational processing, and such influences are susceptible to memory tasks. Thus, our findings provide compelling evidence for both the dual-process memory theory and the retrieval strategy disruption hypothesis. Future research is recommended to examine more influential factors.