When true recognition suppresses false recognition: Evidence from amnesic patients

False recognition occurs when people mistakenly claim that a novel item is familiar. After studying lists of semantically related words, healthy contr ols show extraordinarily high levels of false recognition to nonstudied lur es that are semantic associates of study list words. In previous experiment s, we found that both Korsakoff and non-Korsakoff amnesic patients show red uced levels of false recognition to semantic associates, implying that the medial temporal/diencephalic structures that are damaged in amnesic patient s are involved in the encoding and/or retrieval of information that underli es false recognition. These data contrast with earlier results indicating g reater false recognition in Korsakoff amnesics than in control subjects. Th e present experiment tests the hypothesis that greater or lesser false reco gnition of semantic associates in amnesic patients, relative to normal cont rols, can be demonstrated by creating conditions that are more or less cond ucive to allowing true recognition to suppress false recognition. With repe ated presentation and testing of lists of semantic associates, control subj ects and both Korsakoff and non-Korsakoff amnesics showed increasing levels of true recognition across trials. However, control subjects exhibited dec reasing levels of false recognition across trials, whereas Korsakoff amnesi c patients showed increases across trials and non-Korsakoff amnesics showed a fluctuating pattern. Consideration of signal detection analyses and diff erences between the two types of amnesic patients provides insight into how mechanisms of veridical episodic memory can be used to suppress false reco gnition.