Response to commentaries on our review of Fast Mapping in adults

No evidence of fast mapping in healthy adults using an implicit memory measure: failures to replicate the lexical competition results of Coutanche and Thompson-Schill (2014)

Fast mapping (FM) is a hypothetical, incidental learning process that allows rapid acquisition of new words. Using an implicit reaction time measure in a FM paradigm, Coutanche and Thompson-Schill (Coutanche, M. N., & Thompson-Schill, S. L. (2014). Fast mapping rapidly integrates information into existing memory networks. Journal of Experimental Psychology: General, 143(6), 2296-2303. https://doi.org/10.1037/xge0000020) showed evidence of lexical competition within 10 min of non-words being learned as names of unknown items, consistent with same-day lexicalisation. Here, Experiment 1 was a methodological replication (N = 28/group) that found no evidence of this RT competition effect. Instead, a post-hoc analysis suggested evidence of semantic priming. Experiment 2 (N = 60/group, online study, pre-registered on OSF) tested whether semantic priming remained when making the stimulus set fully counterbalanced. No evidence for either lexical competition nor semantic priming was detected. Experiment 3 (n = 64, online study, pre-registered on OSF) tested whether referent (a)typicality boosted lexical competition (Coutanche, M. N., & Koch, G. E. (2017). Variation across individuals and items determine learning outcomes from fast mapping. Neuropsychologia, 106, 187-193. https://doi.org/10.1016/j.neuropsychologia.2017.09.029), but again no evidence of lexical competition was observed, and Bayes Factors for the data combined across all three experiments supported the hypothesis that there is no effect of lexical competition under FM conditions. These results, together with our previous work, question whether fast mapping exists in healthy adults, at least using this specific FM paradigm.

More Stable Memory Retention of Novel Words Learned from Fast Mapping than from Explicit Encoding

There is a heated debate on a learning paradigm known as "fast mapping" for its early neocortical dependence and retained memory over time for amnesic patients with hippocampal system damage. Whether the fast mapping allows hippocampus independent learning and induces rapid integration is poorly understood. The present study aims to investigate the effect of fast mapping on very long-term retention, which to our knowledge has not been previously explored. We tested memory retention ranging from 10 min to 1.5 years, for novel word-object associations learned from fast mapping or explicit encoding procedures. The three-alternative forced choice recognition task was employed to assess memory performance. Besides the slight adjustment of the testing schedule, other settings remained the same in Experiment 2 to replicate and verify the findings of Experiment 1. Results showed that overall memory retrieval performance was higher after explicit encoding as compared to fast mapping. However, retrieval performance after explicit encoding dropped after 1.5 years, but remained stable in the fast mapping condition. Furthermore, matching the semantic category of the known and the novel items during the fast mapping paradigm might affect long-term retention. These results suggest that fast mapping creates more stable long-term memory representations as compared to the explicit encoding strategy.

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.