Toddlers’ causal interventions reveal a grasp of the temporal priority principle

This study investigated whether one- and two-year-olds (N=133, 72 female, Western) grasp that causes must precede their effects (the temporal priority principle). Toddlers watched an adult perform action A on a puzzle-box, following which a sticker dispensed (effect E); following which action B was performed. In line with the temporal priority principle, toddlers were significantly more likely to manipulate A than B (Experiment 1), even when A was spatially disconnected from the sticker dispenser and further from it than action B (Experiment 2). Experiment 3 ruled out that toddlers acted based on a primacy effect in Experiments 1—2. A lack of evidence for any age effects suggests children grasp temporal priority from the second year of life.

Effect of milk protein content in Toddler formula on later BMI and obesity risk: protocol of the multicentre randomised controlled Toddler Milk Intervention (ToMI) trial

IntroductionReduction of milk protein content in infant formula provided during the first year of life has been shown to reduce early weight gain and obesity later in life. While rapid weight gain during the first 2 years of life is one of the strongest early predictors of obesity, the role of animal protein intake beyond the first year of life is unclear. The aim of this study is to examine the role of milk protein during the second year of life in healthy children on weight gain and obesity risk in preschool age.Methods and analysisThis randomised, double-blinded study enrolled 1618 children aged 11.5–13.5 months in Spain and Germany into two groups receiving isocaloric toddler milk with differing protein content during the second year of life. The experimental formula contains 1.5 g/100 kcal and the control formula 6.15 g/100 kcal protein and otherwise equal formula composition, except for modified fat content to achieve equal energy density. The primary endpoint is body mass index (BMI)-for-age z-score at the age of 24 months adjusted for BMI at 12 months of age. The children are followed until 6 years of age.Ethics and disseminationEthics approval was obtained from the ethical committees of the LMU University Hospital Munich, Germany (Nr. 555-15) and at Institut d’Investigació Sanitaria Pere Virgili, Reus, Spain (Ref. CEIm IISPV 013/2016). We aim at publishing results in peer-reviewed journals and sharing of results with study participants.Trial registration numberNCT02907502.

The Origins of Trust: Humans’ Reliance on Communicative Cues Supersedes Firsthand Experience During the Second Year of Life

How do people learn about things that they have never perceived or inferred—like molecules, miracles or Marie-Antoinette? For many thinkers, trust is the answer. Humans rely on communicated information, sometimes even when it contradicts blatantly their firsthand experience. We investigate the early ontogeny of this trust using a non-verbal search paradigm in four main studies and three supplementary studies (N = 208). Infants and toddlers first see where a reward is, and then an in-formant communicates to them that it is in another location. We use this general experimental set-up to assess the role of age, informants’ knowledge, cue’s familiarity, and communicative context on trust in communicated information. Results reveal that infants and toddlers quickly trust familiar and novel communicative cues from well-informed adults. When searching for the reward, they follow a well-informed adults’ communicative cue, even when it contradicts what they just saw. Further-more, infants are less likely to be guided by familiar and novel cues from poorly informed adults than toddlers. Thus, reliance on communication is calibrated during early childhood, up to the point of overriding evidence about informants’ knowledge. Moreover, toddlers trust much more strongly a novel cue when it is used in a communicative manner. Toddlers’ trust cannot be explained by mere compliance: it is highly reduced when communicated information is pitted against what participants currently see. Thus, humans’ strong tendency to rely on familiar and novel communicative cues emerges in infancy, and intensifies during the second year of life.

Professor Igor V. Prianikov (08.04.1959-12.03.2021)

On March 12, 2021 at the sixty-second year of life, a member of the editorial colleague of the journal "Clinical Nutrition and Metabolism", Professor, Doctor of Medical Sciences Igor Valentinovich Pryanikov suddenly passed away. Talented, intelligent, with an amazing sense of humor, Igor Valentinovich has always inspired his colleagues with his positive attitude, boiling energy and ability to work.

Which Milk during the Second Year of Life: A Personalized Choice for a Healthy Future?

Nutrition in early life is a crucial element to provide all essential substrates for growth. Although this statement may appear obvious, several studies have shown how the intake of micro and macronutrients in toddlers differs a lot from the recommendations of scientific societies. Protein intake often exceeds the recommended amount, while the intake of iron and zinc is frequently insufficient, as well as Vitamin D. Nutritional errors in the first years of life can negatively impact the health of the child in the long term. To date, no clear evidence on which milk is suggested during the second year of life is yet to be established. In this study, we compare the nutrient profiles of cow’s milk and specific formulas as well as nutritional risks in toddlers linked to growth and childhood obesity development. The purpose of this review is to resume the latest clinical studies on toddlers fed with cow’s milk or young children formula (YCF), and the potential risks or benefits in the short and long term.

Cognitive Dissonance from 2 years of age: Toddlers’, but not infants’, blind choices induce preferences

As adults, not only do we choose what we prefer, we also tend to adapt our preferences according to our previous choices. We do this even when our choices were blind and we could not have had any previous preference for the option we chose. These blind choice-induced preferences are thought toresult from cognitive dissonance as an effort to reconcile our choices and values. In the present preregistered study, we asked when this phenomenon develops. We reasoned that cognitive dissonance may emerge around 2 years of age in connection with the development of children’s self-concept. We presented N=200 children aged 16 to 36 months with a blind choice between two toys, and then tested whether their choice had induced a preference for the chosen, and a devaluation of the discarded, toy. Indeed, children’s choice-induced preferences substantially increased with age. 26- to 36-months-old children preferred a neutral over the previously blindly discarded toy, but the previously chosen over the neutral toy, in line with cognitive dissonance predictions. Younger infants showed evidence against such blind choice-induced preferences, indicating its emergence around 2 years of age. Contrary to our hypotheses, the emergence of blind choice-induced preferences was not related to measures of self-concept development in the second year of life. Our results suggest that cognitive dissonance develops around 2 years. We speculate about cognitive mechanisms that underlie this development, including later-developing aspects of the self-concept and increasingly abstract representational abilities.