Forgetting at short term: When do event-based interference and temporal factors have an effect?

Memory tasks combining storage and distracting tasks performed at either encoding or retrieval have provided divergent results pointing towards accounts of forgetting in terms of either temporal decay or event-based interference respectively. The aim of this study was to shed light on the possible sources of such a divergence that could rely on methodological aspects or deeper differences in the memory traces elicited by the different paradigms used. Methodological issues were explored in a first series of experiments by introducing at retrieval computer-paced distracting tasks that involved articulatory suppression, attentional demand, or both. A second series of experiments that used a similar design was intended to induce differences in the nature of memory traces by increasing the time allowed for encoding the to-be-remembered items. Although the introduction of computer-paced distracting tasks allowed for a strict control of temporal parameters, the first series of experiments replicated the effects usually attributed to event-based interference. However, deeper encoding abolished these effects while time-related effects remained unchanged. These findings suggest that the interplay between temporal factors and event-based interference in forgetting at short term is more complex than expected and could depend on the nature of memory traces.

► We compare memory tasks combining storage and processing at encoding or recall. ► The two paradigms have previously provided divergent results. ► We show that this is not due to task setting but to the nature of memory traces. ► Superficial encoding makes memory traces susceptible to interference. ► Consolidated memory traces resist interference but are prone to temporal decay.