Statistical treatment of looking-time data. Developmental Psychology. 2016;52(4):521-36. Abstract
Statistical treatment of looking-time data
Looking times (LTs) are frequently measured in empirical research on infant cognition. We analyzed the statistical distribution of LTs across participants in order to develop recommendations for their treatment in infancy research. Our analyses focused on a common within-subject experimental design, in which longer looking to novel or unexpected stimuli is predicted. We analyzed data from two sources: an in-house set of LTs that included data from individual participants (47 experiments, 1584 observations), and a representative set of published papers reporting group-level LT statistics (149 experiments from 33 papers). We established that LTs are log-normally distributed across participants, and therefore should always be log-transformed before parametric statistical analyses. We estimated the typical size of significant effects in LT studies, which allowed us to make recommendations about setting sample sizes. We show how our estimate of the distribution of effect sizes of LT studies can be used to design experiments to be analyzed by Bayesian statistics, where the experimenter is required to determine in advance the predicted effect size rather than the sample size. We demonstrate the robustness of this method in both sets of LT experiments.
Probing the strength of infants' preference for helpers over hinderers: Two replication attempts of Hamlin and Wynn (2011)
Several studies indicate that infants prefer individuals who act prosocially over those who act antisocially toward unrelated third parties. In the present study, we focused on a paradigm published by Kiley Hamlin and Karen Wynn in 2011. In this study, infants were habituated to a live puppet show in which a protagonist tried to open a box to retrieve a toy placed inside. The protagonist was either helped by a second puppet (the “Helper”), or hindered by a third puppet (the “Hinderer”). At test, infants were presented with the Helper and the Hinderer, and encouraged to reach for one of them. In the original study, 75% of 9-month-olds selected the Helper, arguably demonstrating a preference for prosocial over antisocial individuals. We conducted two studies with the aim of replicating this result. Each attempt was performed by a different group of experimenters. Study 1 followed the methods of the published study as faithfully as possible. Study 2 introduced slight modifications to the stimuli and the procedure following the guidelines generously provided by Kiley Hamlin and her collaborators. Yet, in our replication attempts, 9-month-olds’ preference for helpers over hinderers did not differ significantly from chance (62.5% and 50%, respectively, in Studies 1 and 2). Two types of factors could explain why our results differed from those of Hamlin and Wynn: minor methodological dissimilarities (in procedure, materials, or the population tested), or the effect size being smaller than originally assumed. We conclude that fine methodological details that are crucial to infants’ success in this task need to be identified to ensure the replicability of the original result.
Human infants' learning of social structures: The case of dominance hierarchy. Psychological Science. 2014;25(1):250-5. Abstract
Human infants' learning of social structures: The case of dominance hierarchy
This paper investigates whether human infants go beyond learning about individual social partners and their relations, and form hypotheses about how social groups are organized. We test 15-month-olds’ capacity to represent social dominance hierarchies with more than two agents. Infants find it harder to memorise dominance relations presented in an order that hinders the incremental formation of a single structure (Study 1). Thus, infants attempt to build structures incrementally, relation by relation, thereby simplifying the complex problem of recognizing a social structure. Infants also find circular dominance structures harder to process than linear ones (Study 2). These expectations about the shape of structures may facilitate learning. Our results suggest that infants attempt to represent social structures composed of social relations.
Representation of stable social dominance relations by human infants. Proceedings of the National Academy of Sciences of the United States of America. 2012;109(18):6862-7. Abstract
Representation of stable social dominance relations by human infants
What are the origins of humans’ capacity to represent social relations? We approached this question by studying human infants’ understanding of social dominance as a stable relation. We presented infants with interactions between animated agents in conflict situations. Studies 1 and 2 targeted expectations of stability of social dominance. They revealed that 15-montholds (and to a lesser extent 12-month-olds) expect an asymmetric relationship between two agents to remain stable from one conflict to another. To do so, infants need to infer that one of the agents (the dominant) will consistently prevail when her goals conflict with those of the other (the subordinate). Study 3 and 4 targeted the format of infants’ representation of social dominance. In these studies, we found that 12- and 15-month-olds did not extend their expectations of dominance to unobserved relationships, even when they could have been established by transitive inference. This suggests that infants' expectation of stability originates from their representation of social dominance as a relationship between two agents rather than as an individual property. Infants’ demonstrated understanding of social dominance reflects the cognitive underpinning of humans’ capacity to represent social relations, which may be evolutionarily ancient, and may be shared with non-human species.
L’éveil du mensonge. Terrain. 2011;57:20-35.
Epistemic vigilance
Humans massively depend on communication with others, but this leaves them open to the risk of being accidentally or intentionally misinformed. To ensure that, despite this risk, communication remains advantageous, humans have, we claim, a suite of cognitive mechanisms for epistemic vigilance. Here we outline this claim and consider some of the ways in which epistemic vigilance works in mental and social life by surveying issues, research and theories in different domains of philosophy, linguistics, cognitive psychology and the social sciences.
Inacurate speakers are not always less knowledgeable. Human Development. 2010;53:170-2.
The moral, epistemic and mindreading components of children’s vigilance towards deception. Cognition. 2009;112:367-80. Abstract
The moral, epistemic and mindreading components of children’s vigilance towards deception
Vigilance towards deception is investigated in 3- to-5-year-old children: (i) In Study 1, children as young as 3 years of age prefer the testimony of a benevolent rather than of a malevolent communicator. (ii) In Study 2, only at the age of four do children show understanding of the falsity of a lie uttered by a communicator described as a liar. (iii) In Study 3, the ability to recognize a lie when the communicator is described as intending to deceive the child emerges around four and improves throughout the fifth and sixth year of life. On the basis of this evidence, we suggest that preference for the testimony of a benevolent communicator, understanding of the epistemic aspects of deception, and understanding of its intentional aspects are three functionally and developmentally distinct components of epistemic vigilance.