Although priming of familiar stimuli is usually age invariant, little is known about how aging affects priming of pre-experimentally unfamiliar stimuli. Therefore, this study investigated the effects of aging and encoding-to-test delays (0 min, 20 min, 90 min, and 1 week) on priming of unfamiliar objects in block-based priming paradigms. During the encoding phase, subjects viewed pictures of novel objects (Experiments 1 and 2) or novel and familiar objects (Experiment 3) and judged their left/right orientation. In the test block, priming was measured using the possible/impossible objectdecision test (Experiment 1), symmetric/asymmetric object-decision test (Experiment 2), and real/ non-real object-decision test (Experiment 3). In Experiments 1 and 2, young adults showed priming for unfamiliar objects at all delays, whereas older adults whose baseline task performance was similar to that of young adults did not show any priming. Experiment 3 found no effects of age or delay on priming of familiar objects; however, priming of unfamiliar objects was only observed in the young subjects. This suggests that when older adults cannot rely on pre-existing memory representations, age-related deficits in priming can emerge.
KeywordsPerceptual priming; aging; unfamiliar visual objects; implicit memory; object decision test It is well known that normal aging is accompanied by a reduction in explicit memory, or the ability to consciously recall or recognize previously experienced information (Cabeza, Nyberg, & Park, 2005). In contrast, another type of memory, priming, remains relatively intact in healthy older adults (D. A. Fleischman, 2007;D.A. Fleischman & Gabrieli, 1998;Light, Prull, La Voie, & Healy, 2000). Priming is a type of implicit memory and refers to a change in performance (e.g., speed, accuracy, or bias) for a previously encountered stimulus compared to a new stimulus. Priming can occur in the absence of conscious memory for a stimulus and
NIH-PA Author ManuscriptNIH-PA Author Manuscript NIH-PA Author Manuscript is thought to rely on different neural structures than explicit memory (reviewed in Henson, 2003).Notably, one important theoretical question that has received very little attention in studies of priming is whether intact priming in older adults relies on the existence of pre-existing memory representations. Whereas priming for familiar stimuli is largely based on the reactivation of existing memory representations, priming for novel stimuli has been suggested to be mediated by newly acquired representations (Bowers, 1994(Bowers, , 1996Henson, Shallice, & Dolan, 2000;Schacter, Cooper, & Delaney, 1990). Of the over 100 studies investigating the effects of aging on priming, we are aware of only six studies that used pre-experimentally unfamiliar stimuli (Keane, Wong, & Verfaellie, 2004;Light, Kennison, Prull, LaVoie, & Zuellig, 1996;Light, La Voie, & Kennison, 1995;Schacter, Cooper, & Valdiserri, 1992;Soldan, Gazes, Hilton, & Stern, 2008;Wiggs & Martin, 1994) and all but two them Soldan, Gazes et a...