Fairness is central to morality. Previous research has shown that children begin to understand fairness between the ages of four and six, depending on the context and method used. Within distributive contexts, there is little clear evidence that children have a concept of fairness before the age of five. This research, however, has mostly examined children's explicit verbal responses to questions about unequal distributions-a method that often underestimates children's knowledge. In the current study, we instead examined emotional and behavioral signs that children notice and dislike inequality. We distributed an unequal number of rewards (stickers) among pairs of children (the ages of three to five years) and probed their responses to the inequality.Both implicit and explicit measures revealed that children as young as three years old notice and react negatively to an unfair distribution, particularly when they receive less than their partner. The few age trends that were found involved verbal (explicit) responses, providing evidence that although children do not explicitly talk about fairness until the age of five or six, this talk is an effort to explain emotional reactions that emerged earlier in development.

Emotional development is one of the largest and most productive areas of psychological research. For decades, researchers have been fascinated by how humans respond to, detect, and interpret emotional facial expressions. Much of the research in this area has relied on controlled stimulus sets of adults posing various facial expressions. Here we introduce a new stimulus set of emotional facial expressions into the domain of research on emotional development—The Child Affective Facial Expression set (CAFE). The CAFE set features photographs of a racially and ethnically diverse group of 2- to 8-year-old children posing for six emotional facial expressions—angry, fearful, sad, happy, surprised, and disgusted—and a neutral face. In the current work, we describe the set and report validity and reliability data on the set from 100 untrained adult participants.

The ability to quickly detect potential threat is an important survival mechanism for humans and other animals. Past research has established that adults have an attentional bias for the detection of threat-relevant stimuli, including snakes and spiders as well as angry human faces. Recent studies have documented that preschool children also detect the presence of threatening stimuli more quickly than various non-threatening stimuli. Here we report the first evidence that this attentional bias is present even in infancy. In two experiments, 8- to 14-month-old infants responded more rapidly to snakes than to flowers and more rapidly to angry than to happy faces. These data provide the first evidence of enhanced visual detection of threat-relevant stimuli in infants and hence offer especially strong support for the existence of a general bias for the detection of threat in humans.

Threatening facial expressions can signal the approach of someone or something potentially dangerous. Past research has established that adults have an attentional bias for angry faces, visually detecting their presence more quickly than happy or neutral faces. Two new findings are reported here. First, evidence is presented that young children share this attentional bias. In five experiments, young children and adults were asked to find a picture of a target face among an array of eight distracter faces. Both age groups detected threat-relevant faces--angry and frightened--more rapidly than non-threat-relevant faces (happy and sad). Second, evidence is presented that both adults and children have an attentional bias for negative stimuli overall. All negative faces were detected more quickly than positive ones in both age groups. As the first evidence that young children exhibit the same superior detection of threatening facial expressions as adults, this research provides important support for the existence of an evolved attentional bias for threatening stimuli.

Snakes are among the most common targets of fears and phobias. In visual detection tasks, adults detect their presence more rapidly than the presence of other kinds of visual stimuli. We report evidence that very young children share this attentional bias. In three experiments, preschool children and adults were asked to find a single target picture among an array of eight distractors. Both the children and the adults detected snakes more rapidly than three types of nonthreatening stimuli (flowers, frogs, and caterpillars). These results provide the first evidence of enhanced visual detection of evolutionarily relevant threat stimuli in young children.

Why are snakes such a common target of fear? One current view is that snake fear is one of several innate fears that emerge spontaneously. Another is that humans have an evolved predisposition to learn to fear snakes. In the first study reported here, 9- to 10-month-old infants showed no differential spontaneous reaction to films of snakes versus other animals. In the second study, 7- to 18-month-old infants associated snakes with fear: As predicted, they looked longer at films of snakes while listening to a frightened human voice than while listening to a happy voice. In the third study, infants did not look differentially to still photos of snakes and other animals, indicating that movement is crucial to infants' association of snakes with fear. These results offer support for the view that humans have a natural tendency to selectively associate snakes with fear.

Although cognitive theories of psychopathology suggest that attention bias towards threat plays a role in the etiology and maintenance of anxiety, there is relatively little evidence regarding individual differences in the earliest development of attention bias towards threat. The current study examines attention bias towards threat during its potential first emergence by evaluating the relations between attention bias and known risk factors of anxiety (i.e., temperamental negative affect and maternal anxiety). We measured attention bias to emotional faces in infants (N=98; 57 male) ages 4 to 24 months during an attention disengagement eye-tracking paradigm. We hypothesized that: 1) there would be an attentional bias towards threat in the full sample of infants, replicating previous studies, 2) attentional bias towards threat would be positively related to maternal anxiety, and 3) attention bias towards threat would be positively related to temperamental negative affect. Finally, 4) we explored the potential interaction between temperament and maternal anxiety in predicting attention bias towards threat. We found that attention bias to the affective faces did not change with age, and that bias was not related to temperament. However, attention bias to threat, but not attention bias to happy faces, was positively related to maternal anxiety, such that higher maternal anxiety predicted a larger attention bias for all infants. These findings provide support for attention bias as a putative early mechanism by which early markers of risk are associated with socioemotional development.

Parents commonly dress their baby girls in pink and their baby boys in blue. Although there is research showing that children prefer the colour blue to other colours (regardless of gender), there is no evidence that girls actually have a special preference for the colour pink. This is the focus of the current investigation. In a large cross-sectional study, children aged 7 months to 5 years were offered eight pairs of objects and asked to choose one. In every pair, one of the objects was always pink. By the age of 2, girls chose pink objects more often than boys did, and by the age of 2.5, they had a significant preference for the colour pink over other colours. At the same time, boys showed an increasing avoidance of pink. These results thus reveal that sex differences in young children's preference for the colour pink involves both an increasing attraction to pink by young girls and a growing avoidance of pink by boys.