Recollection and familiarity for public events in neurologically intact older adults and two brain-damaged patients

Despite extensive investigations of the role of recollection and familiarity on laboratory-acquired memories, there is a dearth of such research on memories formed in real life settings. We used the Remember/Know paradigm to investigate the relative contribution of recollection and familiarity processes to memory of public historical events reported in the media across the life span of two groups of neurologically intact older adults (old-old: 74-85, young-old: 58-69) and on two patients with brain damage. First, in neurologically intact participants, recollection rates decreased as a function of time elapsed since the event occurred, at a significantly higher rate than the corresponding decrease in familiarity or global memory. Second, consistent with the hypothesis that memories become increasingly semantic as they age, and that recollection is selectively impaired in older adults, across decades, old-old participants exhibited lower recollection, but not familiarity, relative to young-old participants. Finally, as a demonstration of how this procedure may be applied to studies of clinical populations, we tested two patients, one with medial temporal lesions and another with relative sparing of the medial temporal lobes, but with anterior temporal damage. We found that recollection was disproportionately impaired relative to familiarity across most of the life span in the patient with medial temporal lesions severely while recollection was relatively intact in the patient with anterior lateral temporal damage. We discuss the present results in the context of neuroanatomical and process-oriented theories of how memories age.