What leads to coordinated attention in parent–toddler interactions? Children's hearing status matters

Coordinated attention between children and their parents plays an important role in their social, language, and cognitive development. The current study used head‐mounted eye‐trackers to investigate the effects of children's prelingual hearing loss on how they achieve coordinated attention with their hearing parents during free‐flowing object play. We found that toddlers with hearing loss (age: 24–37 months) had similar overall gaze patterns (e.g., gaze length and proportion of face looking) as their normal‐hearing peers. In addition, children's hearing status did not affect how likely parents and children attended to the same object at the same time during play. However, when following parents' attention, children with hearing loss used both parents' gaze directions and hand actions as cues, whereas children with normal hearing mainly relied on parents' hand actions. The diversity of pathways leading to coordinated attention suggests the flexibility and robustness of developing systems in using multiple pathways to achieve the same functional end.     

Anger arousal,deindividuation, and aggression

We tested the notion that angered persons' aggression would be increased through a process of excitation transfer when they are deindividuated, but that individuated subjects would be most aggressive in circumstances under which they could use the information that they had ingested an arousing drug as a pretext for their aggression. Sixty-two male undergraduates participated under either deindividuated or individuated conditions, ingested either 350 mg of caffeine or a placebo, were informed that they had either taken a stimulant or a nonarousing drug, and were all angered by a confederate. According to prediction, when deindividuated and aroused by caffeine the amount of noxious stimulation subjects delivered to the provocateur was greater if they believed that the drug they had taken was nonarousing than if they thought it was a stimulant; in contrast, individuated subjects' aggression was greater when aroused subjects believed the drug was a stimulant. The results are discussed in terms of excitation transfer and the effect of aggression inhibition on the use of information about one's arousal.     

The maximization of overall reinforcement rate on concurrent chains

We model behavioral allocation on concurrent chains in which the initial links are independent variable-interval schedules. We also quantify the relationship between behavior during the initial links and the probability of entering a terminal link. The behavior that maximizes overall reinforcement rate is then considered and compared with published experimental data. Although all the trends in the data are predicted by rate maximization, there are considerable deviations from the predictions of rate maximization when reward magnitudes are unequal. We argue from our results that optimal allocation on concurrent chains, and prey choice as used in the theory of optimal diets, are distinct concepts. We show that the maximization of overall rate can lead to apparent violations of stochastic transitivity.