Publications of Hernik, M.

A two-lab direct replication attempt of Southgate, Senju, & Csibra (2007)

The study by Southgate, V., Senju, A., and Csibra, G. (Southgate et al., 2007) has been widely cited as evidence for the ability of false-belief attribution in young children. Recent replication attempts of this paradigm have yielded mixed results: several studies were unable to replicate the original finding, raising doubts about the suitability of the paradigm to assess non-verbal action prediction and Theory of Mind. In a preregistered collaborative study including two of the original authors, we tested 160 24- to 26-month-olds across two locations following the original stimuli, procedure, and analyses as closely as possible. We found no evidence for action anticipation: only about half of the infants correctly anticipated the protagonist’s actions when action prediction did not require taking into account the agent’s beliefs. In addition, even those who appeared to anticipate failed to do so when a false belief was involved. These findings indicate that the paradigm of Southgate et al. (2007) cannot reliably elicit anticipatory action prediction and is unsuitable for testing false belief understanding in 2-year-olds.

Minimal cues of possession transfer compel infants to ascribe the goal of giving

Human infants’ readiness to interpret impoverished object-transfer events as acts of giving suggests the existence of a dedicated action schema for identifying interactions based on active object transfer. Here we investigated the sensitivity of this giving schema by testing whether 15-month-olds would interpret the displacement of an object as an agent’s goal even if it could be dismissed as side effect of a different goal. Across two looking-time experiments, we showed that, when the displacement only resulted in a change of object location, infants expected the agent to pursue the other goal. However, when the same change of location resulted in a transfer of object possession, infants reliably adopted this outcome as the agent’s goal. The interpretive shift that the mere presence of a potential recipient induced is testament to the infants’ susceptibility to cues of benefit delivery: an action efficiently causing a transfer of object possession appeared sufficient to induce the interpretation of goal-directed giving even if the transfer was carried out without any interaction between Giver and Givee and was embedded in an event affording an alternative goal interpretation.

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.

Infants learn enduring functions of novel tools from action demonstrations

According to recent theoretical proposals, one function of infant goal attribution is to support early social learning of artifact functions from instrumental actions, and one function of infant sensitivity to communication is to support early acquisition of generic knowledge about enduring, kind-relevant properties of the referents. The present study tested two hypotheses, derived from these proposals, about the conditions that facilitate the acquisition of enduring functions for novel tools in human infancy. Using a violation-of-expectation paradigm, we show that 13.5-months-old infants encode arbitrary end-states of action-sequences in relation to the novel tools employed to bring them about. These mappings are not formed if the same end states of action sequences cannot be interpreted as action goals. Moreover, the tool-goal mappings acquired from infant-directed communicative demonstrations are more resilient to counter-evidence than those acquired from non-infant-directed presentations, and thus show similarities to generic rather than episodic representations. These findings suggest that the acquisition of tool functions in infancy is guided by both teleological action interpretation mechanisms and the expectation that communicative demonstrations reveal enduring dispositional properties of tools.

Functional understanding facilitates learning about tools in human children

Human children benefit from a possibly unique set of adaptations facilitating the acquisition of knowledge about material culture. They represent artifacts (man-made objects) as tools with specific functions and seek for functional information about novel objects. Even young infants pay attention to functionally relevant features of objects, and learn tool use and infer tool functions from others’ goal-directed actions and demonstrations. Children tend to imitate causally irrelevant elements of tool use demonstrations, which helps them to acquire means actions even before they fully understand their causal role in bringing about the desired goal. Although non-human animals use and make tools, and recognize causally relevant features of objects in a given task, they - unlike human children - do not appear to form enduring functional representations of tools as being for achieving particular goals when they are not in use.