Robustness of the rule‐learning effect in 7‐month‐old infants: A close, multicenter replication of Marcus et al. (1999)

Abstract

We conducted a close replication of the seminal work by Marcus and colleagues from 1999, which showed that after a brief auditory exposure phase, 7-month-old infants were able to learn and generalize a rule to novel syllables not previously present in the exposure phase. This work became the foundation for the theoretical framework by which we assume that infants are able to learn abstract representations and generalize linguistic rules. While some extensions on the original work have shown evidence of rule learning, the outcomes are mixed, and an exact replication of Marcus et al.'s study has thus far not been reported. A recent meta-analysis by Rabagliati and colleagues brings to light that the rule-learning effect depends on stimulus type (e.g., meaningfulness, speech vs. nonspeech) and is not as robust as often assumed. In light of the theoretical importance of the issue at stake, it is appropriate and necessary to assess the replicability and robustness of Marcus et al.'s findings. Here we have undertaken a replication across four labs with a large sample of 7-month-old infants (N = 96), using the same exposure patterns (ABA and ABB), methodology (Headturn Preference Paradigm), and original stimuli. As in the original study, we tested the hypothesis that infants are able to learn abstract "algebraic" rules and apply them to novel input. Our results did not replicate the original findings: infants showed no difference in looking time between test patterns consistent or inconsistent with the familiarization pattern they were exposed to.

Robustness of the cognitive gains in 7‐month‐old bilingual infants: A close multi‐center replication of Kovács and Mehler (2009)

“…Our replication of the seminal Kovács and Mehler (2009) study stresses the importance of exact replications in the field of developmental science in multiple labs (Frank et al., 2017; Geambașu et al., 2022; The ManyBabies Consortium, 2020) in combination with more advanced statistical techniques (Bayes; Cluster‐based; logistic regression). Our inability to replicate the original findings not only for this study, but also for another infant study on rule learning (i.e., Marcus et al.…”

“…Our inability to replicate the original findings not only for this study, but also for another infant study on rule learning (i.e., Marcus et al. (1999)—see Geambașu et al., 2022) highlights the necessity of repeated replication attempts to obtain a better understanding of the factors that may or may not contribute to the building blocks of infant cognition.…”

“…This experiment used a linguistic pattern as a cue for visual switching, “because 7‐month‐old infants and even newborns discriminate these regularities” (Kovács & Mehler, 2009, p. 6557). Although the original evidence that this claim was based on (Marcus et al., 1999) has been debated (Geambașu et al., 2022), we might still argue that this experiment provides the most direct test of the idea that bilingualism leads to a cognitive advantage. The presence of structured linguistic input in the experiment could be helpful in anticipating where the visual stimulus will occur, and thus guide switching behavior.…”

“…In order to be able to verify the robustness and generalizability of these results, a replication is necessary. Here we undertake a multi‐center replication (see Frank et al., 2017; Geambașu et al., 2022; The ManyBabies Consortium, 2020 for the importance of such attempts), albeit in a different country, and with infants acquiring different languages than in the original study, which was carried out in Italy and included mostly Italian‐Slovenian bilingual infants. Except for these changes, we remained as faithful as possible to the original study.…”

Bayesian sample size planning for developmental studies

“…The average effect size was estimated as g = 0.25, 95% CI = [0.09, 0.40] (Rabagliati et al, 2019). A recent study in 4 Dutch babylabs found no evidence for rule learning in a close replication of the original paradigm (Geambas et al, 2023).…”