Some memories are odder than others: Judgments of episodic oddity violate known decision rules

Akira R. O'Connor, Emily N. Guhl, Justin C. Cox, Ian G. Dobbins

Research output: Contribution to journalArticlepeer-review

10 Scopus citations


Current decision models of recognition memory are based almost entirely on one paradigm, single item old/new judgments accompanied by confidence ratings. This task results in receiver operating characteristics (ROCs) that are well fit by both signal-detection and dual-process models. Here we examine an entirely new recognition task, the judgment of episodic oddity, whereby participants select the mnemonically odd members of triplets (e.g., a new item hidden among two studied items). Using the only two known signal-detection rules of oddity judgment derived from the sensory perception literature, the unequal variance signal-detection model predicted that an old item among two new items would be easier to discover than a new item among two old items. In contrast, four separate empirical studies demonstrated the reverse pattern: triplets with two old items were the easiest to resolve. This finding was anticipated by the dual-process approach as the presence of two old items affords the greatest opportunity for recollection. Furthermore, a bootstrap-fed Monte Carlo procedure using two independent datasets demonstrated that the dual-process parameters typically observed during single item recognition correctly predict the current oddity findings, whereas unequal variance signal-detection parameters do not. Episodic oddity judgments represent a case where dual- and single-process predictions qualitatively diverge and the findings demonstrate that novelty is " odder" than familiarity.

Original languageEnglish
Pages (from-to)299-315
Number of pages17
JournalJournal of Memory and Language
Issue number4
StatePublished - May 2011


  • Cognitive models
  • Episodic memory
  • Recognition


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