Unitization and temporality in associative memory: Evidence from modulation of context effects Roni Tibon a,⇑ , Eli Vakil a,b , Abraham Goldstein a,b , Daniel A. Levy c,⇑ a Department of Psychology, Bar-Ilan University, Ramat-Gan 52900, Israel b Gonda Multidisciplinary Brain Research Center, Bar-Ilan University, Ramat-Gan 52900, Israel c School of Psychology, The Interdisciplinary Center, Herzliya 46150, Israel article info Article history: Received 28 September 2011 revision received 6 February 2012 Available online 3 March 2012 Keywords: Association Context Episodic memory Familiarity Recollection abstract It has been proposed that the formation of episodic associations between stimuli may involve different processes when memoranda are from the same or different perceptual domains, and when stimuli are experienced concurrently or sequentially. Such differences are postulated to determine the degree of unitization of memoranda, and are asserted to influence whether such associations are later retrieved via familiarity or recollection. In two experiments utilizing the context effects (CEs) paradigm, we examined effects on asso- ciative memory observed when unitization of memoranda is not readily achieved, due to domain differences between stimuli or to asynchronous presentation. In both cases, the standard associative-binding CE of better recognition of probes under contextual reinstate- ment (i.e., higher hit rates for pairs of repeated probes vs. re-paired probes) was only found when participants explicitly recognized the context stimuli. These results contrast with earlier findings that for concurrent encoding of same-domain stimuli, CEs are obtained even in the absence of explicit memory for contexts. The contrast supports the assertion that in the absence of unitization associative memory is dependent on recollection, while unitized associations may be supported by familiarity strength. Ó 2012 Elsevier Inc. All rights reserved. Introduction Inherent in our most basic ideas about memory is its ability to represent not only discrete stimuli, but also the spatio-temporal relationships between them – i.e., epi- sodic associations. Although episodic associations have been the topic of much research, numerous significant questions about this aspect of memory remain open. Two of the many extant questions are whether common cogni- tive processes and neural structures are responsible for the encoding, storage, and retrieval of all forms of episodic associations, and whether the same episodic associative process binds stimuli across separation in space and sepa- ration in time. In the current study, we attempt to address these two questions. Stimuli perceived simultaneously may be experienced as independent entities or as a gestalt. Unitization refers to the perception and encoding of a number of discrete stimuli as a single unit (Graf & Schacter, 1989; LaBerge & Samuels, 1974). A recent taxonomy of episodic association has pro- posed that associative memory comprises three types of associations, reflecting differing degrees of unitization: in- tra-item associations, i.e., items that were unitized into one entity (e.g., two interactively encoded objects); with- in-domain associations, formed between similar kinds of items that are not remembered as one entity (e.g., two unre- lated words); and between-domain associations, formed between different kind of items or modalities, such as faces and voices (Mayes, Montaldi, & Migo, 2007). Unitization is postulated to have manifold effects on associative memory. Yonelinas, Kroll, Dobbins, and Soltani (1999) proposed that unitized stimuli may be recognized via processes that rely on familiarity rather than recollection. Following up on that proposal, Bastin, van der Linden, Schnakers, Montaldi, and 0749-596X/$ - see front matter Ó 2012 Elsevier Inc. All rights reserved. doi:10.1016/j.jml.2012.02.003 ⇑ Corresponding authors. E-mail addresses: ronitibon@gmail.com (R. Tibon), daniel.levy@idc. ac.il (D.A. Levy). Journal of Memory and Language 67 (2012) 93–105 Contents lists available at SciVerse ScienceDirect Journal of Memory and Language journal homepage: www.elsevier.com/locate/jml