An analysis of signal detection and threshold models of source memory.

Abstract

The authors analyzed source memory performance with an unequal-variance signal detection theory model and compared the findings with extant threshold (multinomial and dual-process) models. In 3 experiments, receiver operating characteristic (ROC) analyses of source discrimination revealed curvilinear functions, supporting the relative superiority of a continuous signal detection model when compared with a threshold model. This result has implications for both multinomial and dual-process models, bom of which assume linear ROCs in their description of source memory performance.Source memory refers to memory for the context in which information was acquired (Johnson, Hashtroudi, & Lindsay, 1993). For example, memory for the person with whom one is conversing or the place where one is conversing can be interpreted as source memory. In psychological experiments, source memory is typically assessed by asking participants to determine the origin of previously presented information, such as whether the information was presented verbally or visually, presented by a male or a female voice, or presented in one spatial location or another. As these examples imply, source memory depends on memory for autobiographical or episodic information. Various cognitive and neuropsychological findings have suggested that, to some degree, memory for source can be dissociated from item memory (see Dodson & Shimamura, 2000;Johnson, Kounios, & Reeder, 1994;Schacter, Harbluk, & McLachlan, 1984;Shimamura & Squire, 1987;Zaragoza & Lane, 1994). Indeed, various models of memory suggest a distinction that is related to differences between item and source memory (e.g., Gardiner, 1988;Hirst, 1982;Jacoby, 1991;Johnson et al., 1993;Mayes, Meudell, & Pickering, 1985;Tulving, 1972). Johnson et al. (1993) developed a useful framework for the analysis of source memory. In this "source monitoring" framework, the degree to which individuals identify the source of a memory depends, in part, on the kind of information that is acquired and remembered. That is, one can remember various aspects of a learning episode, such as perceptual information,

Item memory, source memory, and the medial temporal lobe: Concordant findings from fMRI and memory-impaired patients

“…1 shows that words for which participants have stronger memory are also words for which they are likely to make correct source judgments. This finding has been reported for other item memory tasks and source memory tasks as well (18,19) and is consistent with the idea that item memory and source memory lie on a continuum of memory strength. Furthermore, in our study, the confidence ratings associated with forgotten words, item-only words, and item and source words were 2.04 Ϯ 0.09, 2.47 Ϯ 0.07, and 2.76 Ϯ 0.04, respectively.…”

Toward a complete decision model of item and source recognition: A discrete-state approach

“…Slotnick et al (2000) also reported curvilinear source ROCs (pooled across old/new confidence ratings), albeit with a lesser degree of curvature than typically observed for item memory ROCs (see also Hilford et al, 2002). Although this flattening is problematic for the Gaussian assumption of SDT (Green & Swets, 1966), these results broadly support a model in which both item and source judgments are based on continuous processes.…”

“…1997, 1999). This preference is based on research in which confidence ratings for source memory were collected and used to compile so-called receiver-operating characteristic (ROC) functions (Glanzer et al, 2004;Hilford, Glanzer, Kim, & DeCarlo, 2002;Qin, Raye, Johnson, & Mitchell, 2001;Slotnick & Dodson, 2005;Slotnick, Klein, Dodson, & Shimamura, 2000;Yonelinas, 1999). The use of ROC functions is familiar from studies of item memory (for reviews, see Wixted, 2007;Yonelinas & Parks, 2007), in which discrete-state models predict linear ROCs (for binary response formats), whereas signal detection models predict curvilinear ones.…”

Source memory for unrecognized items: Predictions from multivariate signal detection theory

“…With no correlation between recognition and source evidence, the model predicts that discriminability for unrecognized items should equal overall source discriminability (i.e., for recognized and unrecognized items) and should not change on the basis of the position of the recognition criterion. Previous research strongly suggests that recognition and source evidence values are correlated (DeCarlo, 2003;Slotnick & Dodson, 2005;Slotnick et al, 2000), so we do not seriously consider the no-correlation prediction.…”

“…Recently, researchers have begun to explore models based on the continuous retrieval of source information, as opposed to the discrete state of source identification proposed by multinomial models (e.g., Banks, 2000;DeCarlo, 2003;Glanzer, Hilford, & Kim, 2004;Hilford, Glanzer, Kim, & DeCarlo, 2002;Qin, Raye, Johnson, & Mitchell, 2001;Slotnick & Dodson, 2005;Slotnick, Klein, Dodson, & Shimamura, 2000). Figure 2 displays the equal variance signal detection model for source discrimination based on continuous evidence (Wickens, 2002).…”