Abstract
Unitization refers to the creation of a new unit from previously distinct items. The concept of unitization has been used to explain how novel pairings between items can be remembered without requiring recollection, by virtue of new, item-like representations that enable familiarity-based retrieval. We tested an alternative account of unitization – a schema account – which suggests that associations between items can be rapidly assimilated into a schema. We used a common operationalization of “unitization” as the difference between two unrelated words being linked by a definition, relative to two words being linked by a sentence, during an initial study phase. During the following relearning phase, a studied word was re-paired with a new word, either related or unrelated to the original associate from study. In a final test phase, memory for the relearned associations was tested. We hypothesized that, if unitized representations act like schemas, then we would observe some generalization to related words, such that memory would be better in the definition than sentence condition for related words, but not for unrelated words. Contrary to the schema hypothesis, evidence favored the null hypothesis of no difference between definition and sentence conditions for related words (Experiment 1), even when each cue was associated with multiple associates, indicating that the associations can be generalized (Experiment 2), or when the schematic information was explicitly re-activated during Relearning (Experiment 3). These results suggest that unitized associations do not generalize to accommodate new information, and therefore provide evidence against the schema account.
Highlights
Did I put my car keys on the kitchen table? What’s the name of this person? Did I ever see my friend wearing this outfit before? To answer these questions, which can be fundamental to our everyday lives, we need to be able to remember that two or more items were experienced conjointly
Unitization: a traditional Bitem account^ and an alternative Bschema account.^ We rely on a key difference between the two accounts – that the schema account, but not the item account, allows generalization from one association to another related one – and argue that if unitized associations do not display this critical property of schemas, the item account of unitization remains most likely
If current evidence is insufficient to distinguish item and schema accounts of unitization, how can they be tested? We suggest that a key property of the schema but not item account is the potential for generalization
Summary
Did I put my car keys on the kitchen table? What’s the name of this person? Did I ever see my friend wearing this outfit before? To answer these questions, which can be fundamental to our everyday lives, we need to be able to remember that two or more items were experienced conjointly. Unitization – the creation of a new unit from individual items – has been proposed as an effective strategy for remembering such episodic associations (e.g., Gobet et al, 2001; Graf & Schacter, 1989; Yonelinas, 1997; Yonelinas, Kroll, Dobbins, & Soltani, 1999). Memory for episodic associations can be assessed by presenting two items and asking whether they were previously presented together, a task termed Bassociative recognition.^ The widely supported dual-process theory of episodic memory posits that recognition comprises two separable processes: familiarity and recollection. Neurocognitive models of recognition memory claim that, while the hippocampus is necessary for recollection, familiarity is mainly associated with the perirhinal cortex (for review, see Yonelinas, 2002). It has been thought that, while recognition of single items can be supported by either recollection or familiarity, retrieval of newly learnt associations between arbitrary
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