Pictorial encoding effects and memory confusions in the Deese–Roediger–McDermott paradigm: Evidence for the activation of spontaneous imagery

Abstract

The purpose of the experiments reported in this paper was to examine the possible role of spontaneous imagery and list-specific cues on pictorial encoding effects induced by the Deese-Roediger-McDermott (DRM) task. After viewing pictures and words referring to thematically related materials, by way of a picture/word source-judgement task, participants were asked to remember the way in which these materials were presented. Participants reported “seeing” pictures of items that were presented as words, an effect predicted by the imaginal activation hypothesis in its suggestion that incidental images experienced during encoding will later be mistaken as memories for pictures. Whether participants made the same picture misattributions on related lures (or non-presented related items) depended on the way in which the lures’ respective thematic lists were experienced during encoding (Experiments 1 and 2), pointing to the effects of list-specific cues in picture/word judgements. These findings have intriguing implications for interpretations of picture-encoding effects induced by the DRM task. The findings also speak to the use of DRM false-memory rates when marshalling evidence against the use of imagery in applied settings.

Keywords:

• False memories
• Imagery edcoding

Acknowledgements

This research was supported by way of funds associated with an Endowed Chair appointment for Excellence in Teaching awarded to the first author. We thank Janna Belser-Ehrlich, Ian Connole, Jules Martowski, Emily Schlemmer, and Leigh Stokley for help with data collection and scoring.

Notes

¹Source-monitoring tests have been used to examine the basis of other kinds of modality effects—e.g., by asking participants to remember whether items were presented visually or auditorily (Gallo & Roediger, 2003) or by asking participants to remember the voice in which words were read (Mather et al., 1997). In some previous studies examining the effects of mixed picture/word presentation formats with the DRM procedure, both words and pictures were included on picture trials (e.g., Israel & Schacter, 1997). This approach was not used in Experiments 1 or 2 because of concern about its potential effect in introducing confusion when participants were asked to make picture/word source judgements. In this case, participants would essentially be asked to remember what word presentations were accompanied by pictures. Although this might be an interesting variation on source judgements, considering this comparison was not the purpose of the present studies.

²These differences in recognition do not reflect differences between the participants’ interpretations of objects presented as pictures and their corresponding labels used at test. As mentioned in the procedure, the name agreement ratings based on published norms for the pictorial versions used in Experiments 1 and 2 were all quite high, reducing the likelihood of this kind of confusion. More important for this point, at least for the Object Function condition in Experiments 1 and 2, it was possible to confirm that participants’ interpretations of the pictorial versions were consistent with the experimenter's labels. Participants’ descriptions of object functions typically made reference to the experimenter's labels for objects (e.g., “hammer”) and were object appropriate (e.g., “use hammer to pound nails”), suggesting that the objects were recognised and interpreted as intended. In fact, none of the test items (e.g., couch) had to be eliminated from the analyses on responses to presented items because participants labelled them in ways not intended by the experimenter (e.g., referring to a picture of a couch as a futon, or a different kind of object entirely such as a bed).

³The floor effects on responses to new instances and control lures could be a result of the nature of the test items. All of the test items referred to concrete objects, including the items serving as related lures (e.g., chair for the list of furniture items). In DRM studies that do not involve pictorial encoding, related lures and control instances often include abstract items (e.g., sleep or peaceful). In the present experiments, along with other DRM studies involving pictorial encoding, abstract test items were avoided because these terms cannot be presented as pictures.