RESUMO
Test-retest reliability-establishing that measurements remain consistent across multiple testing sessions-is critical to measuring, understanding, and predicting individual differences in infant language development. However, previous attempts to establish measurement reliability in infant speech perception tasks are limited, and reliability of frequently used infant measures is largely unknown. The current study investigated the test-retest reliability of infants' preference for infant-directed speech over adult-directed speech in a large sample (N = 158) in the context of the ManyBabies1 collaborative research project. Labs were asked to bring in participating infants for a second appointment retesting infants on their preference for infant-directed speech. This approach allowed us to estimate test-retest reliability across three different methods used to investigate preferential listening in infancy: the head-turn preference procedure, central fixation, and eye-tracking. Overall, we found no consistent evidence of test-retest reliability in measures of infants' speech preference (overall r = 0.09, 95% CI [-0.06,0.25]). While increasing the number of trials that infants needed to contribute for inclusion in the analysis revealed a numeric growth in test-retest reliability, it also considerably reduced the study's effective sample size. Therefore, future research on infant development should take into account that not all experimental measures may be appropriate for assessing individual differences between infants. RESEARCH HIGHLIGHTS: We assessed test-retest reliability of infants' preference for infant-directed over adult-directed speech in a large pre-registered sample (N = 158). There was no consistent evidence of test-retest reliability in measures of infants' speech preference. Applying stricter criteria for the inclusion of participants may lead to higher test-retest reliability, but at the cost of substantial decreases in sample size. Developmental research relying on stable individual differences should consider the underlying reliability of its measures.
RESUMO
One benefit of working in groups is that group members can learn from each other how to perform the task, a phenomenon called group-to-individual transfer (G-I transfer). In the context of quantitative judgments, G-I transfer means that group members improve their individual accuracy as a consequence of exchanging task-relevant information. This improved individual accuracy allows groups to outperform the average of a comparable number of individuals, that is, G-I transfer leads to synergy. While there is mounting evidence that group members benefit from G-I transfer in quantitative judgment tasks, we still know rather little about what exactly group members learn from each other during this transfer. Here, we build on the distinction between metric knowledge (knowing what constitutes a plausible range of values) and mapping knowledge (knowing the relative magnitude of the targets) to gain further insights into the nature of G-I transfer. Whereas previous research found evidence that G-I transfer improves group members' metric knowledge, there is, so far, no evidence that group discussion also improves mapping knowledge. Using a multicue judgment task, we tested whether group members would benefit from G-I-transfer and, if so, whether this G-I transfer would manifest in the form of improved mapping knowledge. The results of two experiments suggest that this is the case. Participants who worked in real interacting groups outperformed participants who worked individually, and this increase in accuracy was accompanied not only by improved metric but also by increased mapping knowledge. (PsycInfo Database Record (c) 2021 APA, all rights reserved).
