The contribution of recollection and familiarity to yes±no and forced-choice recognition tests in healthy subjects and amnesics Wayne Khoe a , Neal E.A. Kroll a, *, Andrew P. Yonelinas a , Ian G. Dobbins a, 1 , Robert T. Knight b a Department of Psychology, University of California, Davis, USA b Department of Psychology, University of California, Berkeley, USA Received 30 March 1999; received in revised form 25 October 1999; accepted 15 March 2000 Abstract Recent reports suggest that some amnesic patients perform relatively normally on forced-choice recognition memory tests. Their preserved performance may re¯ect the fact that the test relies more heavily on assessments of familiarity, a process that is relatively preserved in these patients, than do other recognition tests such as yes±no tests, which may rely more on recollection. The current study examined recognition memory using yes±no and forced-choice procedures in control and amnesic patients in order to determine whether the two tasks dierentially relied on recollection and familiarity, and whether the extent of the recognition memory de®cit observed in amnesia was dependent upon the type of recognition test used to measure performance. Results using the remember±know procedure with healthy subjects showed that there were no substantial dierences in recognition accuracy or in the contribution of recollection to these two tasks. Moreover, amnesic patients were not found to perform better on a forced-choice test than on a yes±no test, suggesting that familiarity contributed equally to these two types of recognition test. 7 2000 Elsevier Science Ltd. All rights reserved. Keywords: Dual process; Signal detection; Memory assessment; Remember±know 1. Introduction Damage to the medial temporal lobe or diencepha- lon results in anterograde amnesia; this de®cit is most often re¯ected as a pronounced reduction in free recall performance. However, the eects on recognition memory performance are less clear. Some studies have reported that recognition is preserved in amnesia, while others have reported that recognition is impaired [3,9±11,13,19,24]. In a recent meta-analysis of amnesic data, Aggleton and Shaw [1] found that amnesics with restricted hippocampal lesions exhibited near normal performance in the Recognition Memory Test (RMT) [23], but that patients with additional damage outside this region exhibited recognition de®cits. The relatively preserved performance of some amne- sics on tests such as the RMT may re¯ect the fact that the test is based on a forced-choice procedure. This type of procedure may rely more heavily on assess- ments of familiarity, and less on recollection, than do yes±no recognition procedures. Previous studies have shown that amnesia is associated with a pronounced reduction in recollection (i.e., the ability to retrieve qualitative information about a previous episode), but that familiarity (i.e., the ability to evaluate the contex- tual memory strength, or familiarity, of an item) is relatively preserved [11,22,26]. In a forced-choice test, subjects may select the more familiar of the two test items, and thus they may not attempt to recollect qualitative information about the study event. Thus, amnesics may exhibit relatively normal performance Neuropsychologia 38 (2000) 1333±1341 0028-3932/00/$ - see front matter 7 2000 Elsevier Science Ltd. All rights reserved. PII: S0028-3932(00)00055-5 www.elsevier.com/locate/neuropsychologia * Corresponding author. Fax: +1-530-752-2087. E-mail address: ncakroll@ucdavis.edu (N.E.A. Kroll). 1 Present address: Massachusetts General Hospital, Nuclear Mag- netic Resonance Center, Charlestown, MA, USA