Le. James et Dg. Mackay, HM, word knowledge, and aging: Support for a new theory of long-term retrograde amnesia, PSYCHOL SCI, 12(6), 2001, pp. 485-492
This study develops a new theory of long-term retrograde amnesia that encom
passes episodic and semantic memory, including word knowledge. Under the th
eory, retrograde amnesia in both normal individuals and hippocampal amnesic
s reflects transmission deficits caused by aging, nonrecent use of connecti
ons, and infrequent use of connections over the life span. However, transmi
ssion deficits cause severe and irreversible retrograde amnesia only in amn
esics who (unlike normal persons) cannot readily form new connections to re
place nonfunctioning ones. The results of this study are consistent with th
is theory: For low-frequency but not high-frequency words, a famous "hippoc
ampal amnesic" (H.M.) at age 71 performed worse than memory-normal control
participants in a lexical decision experiment and a meaning-definition task
(e.g., What does squander mean?). Also as predicted, H.M.'s lexical decisi
on performance declined dramatically between ages 57 and 71 for low-frequen
cy words, but was age invariant for high-frequency words.