Long-term fragility: Interference susceptibility may be an inherent characteristic of memory traces acquired through fast mapping

Exploring Novel Word Learning Via Fast Mapping and Explicit Encoding in Persons with Temporal Lobe Epilepsy

Objective

To explore novel word learning via fast mapping (FM) and explicit encoding (EE) in temporal lobe epilepsy (TLE).

Methods

16 right and 16 left temporal lobe epilepsy (RTLE and LTLE) patients along with 32 normal controls (NC) underwent learning of 24 novel object name pairs through standard FM and EE techniques. Their learning was assessed via a three-choice alternate delayed recognition task on the day of learning and on the following day. Recognition scores were compared using nonparametric statistics across the groups with P value set at <.05.

Results

RTLE and NC performed similarly, while LTLE and NC differed significantly in novel word learning irrespective of the method of encoding. LTLE and RTLE differed in EE-based novel word learning alone. Further, with respect to encoding techniques, all groups performed better on EE compared to FM. The novel word associations learned via FM showed a lesser decline compared to EE following overnight integration in RTLE and NC.

Conclusion

Novel word learning via FM did not facilitate learning above EE in TLE patients or NC. But FM-based words could better overcome forgetting following overnight integration in RTLE and NC. Hence, it is possible that FM has the potential to improve retention of novel information following overnight integration in RTLE as in NC. However, its efficacy in improving retention in LTLE needs further evidence.

Rapid acquisition through fast mapping: stable memory over time and role of prior knowledge

In recent years, there have been intensive debates on whether healthy adults acquire new word knowledge through fast mapping (FM) by a different mechanism from explicit encoding (EE). In this study, we focused on this issue and investigated to what extent retention interval, prior knowledge (PK), and lure type modulated memory after FM and EE. Healthy young participants were asked to learn novel word-picture associations through both FM and EE. Half of the pictures were from familiar categories (i.e., high PK) and the other half were from unfamiliar categories (i.e., low PK). After 10 min and 1 wk, the participants were tested by forced-choice (FC) tasks, with lures from different categories (Experiment 1) or from the same categories of the target pictures (Experiment 2). Pseudowords were used to denote names of the novel pictures and baseline performance was controlled for each task. The results showed that in both Experiments 1 and 2, memory performance remained stable after FM, while it declined after EE from 10 min to 1 wk. Moreover, the effect of PK appeared at 10 min after FM while at 1 wk after EE in Experiment 2. PK enhanced memory of word-picture associations when the lures were from the same categories (Experiment 2), rather than from different categories (Experiment 1). These results were largely confirmed in Experiment 3 when encoding condition was manipulated as a between-subjects factor, while lure type as a within-subjects factor. The findings suggest that different from EE, FM facilitates rapid acquisition and consolidation of word-picture knowledge, and highlight that PK plays an important role in this process by enhancing access to detailed information.