List-method directed forgetting: Evidence for the reset-of-encoding hypothesis employing item-recognition testing

Abstract

In list-method directed forgetting (LMDF), people are cued to forget a previously studied item list (List 1) and to learn a new list of items (List 2) instead. Such cuing typically enhances memory for the List 2 items, in both recall and (sometimes) item-recognition testing. It has recently been hypothesized that the enhancement effect for List 2 items (partly) reflects the result of a reset-of-encoding process. The proposal is that encoding efficacy decreases with an increase in study material, but the forget cue can reset the encoding process to make the encoding of early List 2 items as effective as the encoding of early List 1 items. An experiment is reported that examined the reset-of-encoding hypothesis with item-recognition testing, examining influences of items' serial learning position on the effects of the forget cue. Item-recognition tests were conducted separately for the two lists. Consistent with the reset-of-encoding hypothesis, the results showed strong enhancement effects for early List 2 items, but hardly any enhancement effects for middle and late List 2 items. Like in previous item-recognition studies, no cuing effects were found for List 1 items. The results support two-mechanism accounts of LMDF, which assume a critical role for a reset-of-encoding process for List 2 enhancement.

Keywords:

• List-method directed forgetting
• Item recognition
• Reset of encoding

The authors thank R. A. Bjork for his comments on a previous version of the manuscript and S. Grimm and F. Welker for their help with data collection.

The authors thank R. A. Bjork for his comments on a previous version of the manuscript and S. Grimm and F. Welker for their help with data collection.

Notes

¹ In contrast to the behavioural studies, the neurocognitive studies examined the reset-of-encoding hypothesis on a list-level basis. Examining the hypothesis on an item level would have required much larger data-sets than were employed in this previous work. Future work is required to fill this empirical gap.

² Consistent with prior recall work (Bäuml et al., 2008; Bäuml & Samenieh, 2012; Zellner & Bäuml, 2006), order of cuing conditions did not affect results. For both List 2 and List 1, no main effect or interaction with order of cuing conditions arose, for both HRs and FARs, all ps > .120.

³ Post-hoc analysis showed that the beneficial effect of cuing on early List 2 items’ d′ was equally present for Items 1–5 (2.61 vs. 1.55) and Items 6–10 (2.09 vs. 1.37), χ²(1) = 1.45, p = .229.

⁴ In both steps of the ROC analysis, we also examined whether parameter σ varied as a function of cuing, testing order and item’s serial learning position. Regarding List 2, the analyses showed that σ was significantly higher in the forget than in the remember condition (1.50 vs. 1.35), χ²(1) = 5.43, p = .020, independent of both testing order and items’ serial position, both χ²(1)s < 1. Regarding List 1, σ did not differ between the forget and the remember condition (1.57 vs. 1.52), χ²(1) = 0.68, p = .410, but was higher when List 1 was tested first than when it was tested second (1.66 vs. 1.46), χ²(1) = 7.75, p = .005. Other effects were non-significant. Also, note that, in all analyses, σ was significantly larger than 1, all ps < .001. This finding is consistent with the UVSD model, which assumes that the standard deviation of the target distribution is larger than the standard deviation of the lure distribution.

⁵ Note, however, that the results from prior recall studies indicate no such influence of item presentation rate on List 2 enhancement, showing no enhancement effects for middle and late List 2 items with presentation rates of 5 s and 6 s per item, at least when List 1 is recalled first and List 2 is recalled last (see Experiments 2 and 3 in Pastötter & Bäuml, 2010).

⁶ Because selective rehearsal and the reset-of-encoding hypothesis make similar predictions regarding List 2 enhancement, but only selective rehearsal and not reset of encoding, makes predictions regarding List 1 forgetting, formally one may regard the reset-of-encoding hypothesis a restrictive variant of selective rehearsal, with the goal of explaining List 2 enhancement but not List 1 forgetting.