Abstracts

The recency effect lies in a better memory of the last items of a studied list compared to previous items, and has been taken as evidence for a distinction of short- (STM) and long-term memory (LTM). However, the recency effect has been found not only during immediate, but also during delayed time points. This lead to an ongoing discussion whether the delayed recency effect is evidence against a distinction of STM and LTM. TLE has been related to decreased LTM but unimpaired STM. So far, in TLE only the immediate recency effect has been investigated. The present study thus analyzed immediate and delayed recency effects on face recognition in TLE., This research is related to two recent studies on face recognition in TLE (Bengner et al., Epilepsy Behav 2006;8:220-227; Bengner et al., Epilepsia; in press). 16 healthy controls, 18 right (R)TLE and 21 left (L)TLE patients learned a serial list of 20 unfamiliar faces. During immediate and 24-hour delayed recognition, learned faces were randomly mixed with 20 unknown distracter faces. The serial position of the studied faces was inverted in relation to the learning phase, so that the delay was kept shortest for the last items learned, and longest for the first items learned (forced [quot]end-first[quot]). After 24-hour recognition of the first list was ended, a second list was studied under proactive interference (PI) by the first list and again had to be recognized immediately and 24 hours later., Controls showed a recency effect during immediate and 24-hour recognition. TLE did not affect the immediate, but erased the delayed recency effect. Similarly, PI did not influence the immediate, but erased the delayed recency effect in controls. RTLE lead to decreased immediate recognition of items from the recent portion of the list compared to LTLE, speaking for a relative STM deficit in RTLE. PI did not alter recency effects in LTLE, but in RTLE, it lead to a further decrease of pre-recency item recognition during immediate and delayed recognition. As a side result, healthy subjects and patients made more false positive answers at the start of the testing trials. This effect was erased by PI., Our results speak for a dissociation of the immediate and delayed recency effect. While TLE or PI influenced the delayed recency effect, they mainly had no influence on the immediate recency effect. This is in accordance with the ideas that TLE is related to LTM-, but not STM-deficits, and that PI decreases LTM, but not STM. We therefore suggest that the immediate recency effect depends on STM, and the delayed recency effect depends on LTM. The relative decrease of immediate recognition of recent portions of the list in RTLE compared to LTLE argues for a subtle short-term memory deficit in RTLE in addition to the long-term memory deficit, found in LTLE and RTLE. In addition, a serial position effect for distracter faces is reported for the first time.,