Memory Strength and the Decision Process in Recognition Memory

Article excerpt

We investigated the role that memory strength plays in the decision process by examining the extent to which strength is used as a cue to dynamically modify recognition criteria. The study list consisted of strong and weak items, with strength a function of study duration or repetition. The recognition test list was divided into two consecutive blocks; strong items appeared in one block, weak items in the other. If the change in item strength across blocks leads to a shift in criterion, the false alarm rate should change accordingly. In four experiments, the false alarm rates did not change across blocks, even when the difference between the strong and the weak items was magnified and marked with semantic cues. However, the strength of the items in the first test block affected the false alarm rate. Thus, strength cues influence initial criterion placement but fail to induce criterion shifts following permanent and even dramatic changes in item strength. These null findings are contrasted with those in a fifth experiment, in which accuracy feedback produced dynamic criterion shifts.

Sitting down at a café, you notice a woman at the next table who seems very familiar. Although you are not certain, you suspect that she may be your wife's friend, whom you recently met at a party. Should you say hello and risk embarrassment if this turns out, after all, to be a stranger? Or should you ignore her and risk insulting a friend of your wife? As this vignette illustrates, every memory judgment has two components. The retrieval process generates information on the basis of a retrieval cue: a feeling of familiarity, remembered details of a past event, and so on. The decision process determines how we act on this information. Historically, memory research has focused on the factors that affect retrieval accuracy, often treating other aspects of the judgment as noise or, at best, as things to be accounted for abstractly. However, the role of the decision process has become increasingly prominent in debates surrounding such issues as false and illusory memories (Hekkanen & McEvoy, 2002; Hirshman & Arndt, 1997; Miller & Wolford, 1999; Verde & Rotello, 2003), mirror effects (Glanzer, Kim, & Adams, 1998; Greene, 1996; Hintzman, Caulton, & Curran, 1994; Hirshman, 1995; Stretch & Wixted, 1998), and subjective awareness and phenomenology (Donaldson, 1996; Dunn, 2004; Hirshman & Henzler, 1998; Rotello, Macmillan, Reeder, & Wong, 2005; Verde, 2004). Moreover, growing appreciation of the richly metacognitive nature of memory places pressure on formal memory models to treat decision processes in a substantive way. Metacognitive accounts of recognition suggest that people rely on stimulus or environmental cues that tell them how to decide that something was encountered in the past. The nature of these cues, however, remains poorly understood. In the present study, we considered the role that memory strength plays in setting decision rules over the course of many recognition judgments.

Signal detection theory (SDT) provides a simple way to quantify the distinction between the retrieval and the decision components of recognition memory. We adopt here a memory strength framework that is prevalent among SDT models of recognition (for reviews, see Banks, 1970; Clark & Gronlund, 1996) and fits intuitively with many less formal approaches. In this view, the retrieval process compares the test probe with the contents of memory, resulting in some degree of match (similarity, learned association, etc.) that can be represented by a scalar value, memory strength. The greater the memory strength, the more evidence there is that the probe represents something encountered in the past. Each class of probe items (old or new) is associated with a distribution along the axis of memory strength, as is illustrated hi Figure 1. Although old items have greater strength on average, the overlap of the distributions introduces uncertainty about whether a given probe has been studied. …


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