Implicit false memory in the DRM paradigm: Effects of amnesia, encoding instructions, and encoding duration.

Abstract

Recent studies with the Deese/Roediger-McDermott (Deese 1959;Roediger & McDermott, 1995) paradigm have revealed that amnesic patients do not only show impaired veridical memory, but also diminished false memory for semantically related lure words. Due to the typically used explicit retrieval instructions, however, this finding may reflect problems at encoding, at recollection, or both. Therefore, the present experiments examined implicit as well as explicit false memory in patients suffering from Korsakoff's syndrome and controls. In Experiment 1, encoding instructions either focused on remembering individual list words, or on discovering semantic relationships among the words. In Experiment 2, different presentation durations were used. Results emphasize the distinction between automatic and intentional retrieval: Korsakoff patients' veridical and false memory scores were diminished when explicit recollection was required, but not when memory was tested implicitly. Encoding manipulations only significantly affected veridical memory: Priming was reduced with thematic encoding, and explicit retrieval was facilitated when given more study time.

Amnesia and the DRM Paradigm: How Encoding Factors (Do Not) Affect Lure Recognition

“…The patients' explicit gist memory was consistently poorer than controls', regardless of whether they had studied lists or stories. Their implicit memory for critical lures was comparable to controls', which also replicates previous findings (Van Damme & d'Ydewalle, 2009a).…”

“…Surprisingly, alcoholic controls differed significantly from healthy controls in false recognition of, and sensitivity for, neutral information, whereas the difference for alcohol-related information was not significant. The former aspect is contrary to the typical finding of similar levels of DRM false memory in memory-intact controls with and without a history of chronic alcoholism (e.g., Schacter et al, 1998;Van Damme & d'Ydewalle, 2009a;Verfaellie et al, 2002). However, evidence also exists that chronic alcoholics suffer from executive function deficits and impaired source monitoring, which may lead to difficulties distinguishing between studied and related items in the DRM paradigm (Harbluk & Weingartner, 1997;Weingartner, Andreason, Hommer, Sirocco, Rio, Ruttimann et al, 1996;see also Pitel, Beaunieux, Witkowski, Vabret, de la Sayette, Viader et al, 2008).…”

“…First, the absence of an effect of encoding context on delayed gist recognition (for both patients and controls) is in line with the claim that relational encoding is the default strategy when participants are intentionally trying to remember word lists (e.g., Lampinen, Leding, Reed, & Odegard, 2006;Van Damme & d'Ydewalle, 2009a; see also Hunt & McDaniel, 1993;McCabe, Presmanes, Robertson, & Smith, 2004). Second, the effect of personally-relevant content on alcoholic controls' source memory and on the ability to suppress false recognition has possible practical implications.…”

“…Results confirmed the expectation of diminished recognition of both studied words and critical lures in Korsakoff patients. Implicit memory for both types of items was normal as compared to controls (cf Van Damme & d'Ydewalle, 2009a;Van Damme & d'Ydewalle, 2010). Delayed gist recognition did not show an influence of encoding context: Korsakoff patients' performance was consistently lower than controls', regardless of whether they had studied stories or lists.…”

“…It should be noted, however, that Verfaellie, Page, Orlando, and Schacter (2005) did find evidence for an encoding deficit as a contributing factor to diminished false memory in a mixed group of amnesic patients. In addition, it has been shown that Korsakoff patients' explicit retrieval of associative information can be improved by giving them additional time and support during the study phase (Van Damme & d'Ydewalle, 2008;Van Damme & d'Ydewalle, 2009a). This suggests that encoding factors do affect the patients' explicit memory performance.…”