The development of emotion recognition from facial expressions and non‐linguistic vocalizations during childhood

Sensitivity to facial and vocal emotion is fundamental to children's social competence. Previous research has focused on children's facial emotion recognition, and few studies have investigated non‐linguistic vocal emotion processing in childhood. We compared facial and vocal emotion recognition and processing biases in 4‐ to 11‐year‐olds and adults. Eighty‐eight 4‐ to 11‐year‐olds and 21 adults participated. Participants viewed/listened to faces and voices (angry, happy, and sad) at three intensity levels (50%, 75%, and 100%). Non‐linguistic tones were used. For each modality, participants completed an emotion identification task. Accuracy and bias for each emotion and modality were compared across 4‐ to 5‐, 6‐ to 9‐ and 10‐ to 11‐year‐olds and adults. The results showed that children's emotion recognition improved with age; preschoolers were less accurate than other groups. Facial emotion recognition reached adult levels by 11 years, whereas vocal emotion recognition continued to develop in late childhood. Response bias decreased with age. For both modalities, sadness recognition was delayed across development relative to anger and happiness. The results demonstrate that developmental trajectories of emotion processing differ as a function of emotion type and stimulus modality. In addition, vocal emotion processing showed a more protracted developmental trajectory, compared to facial emotion processing. The results have important implications for programmes aiming to improve children's socio‐emotional competence.     

The delay-reduction hypothesis: Effects of informative events on response rates and choice

The present study replicated a prior one by Pearce and Collins (1985) in which informative events displayed greater reinforcing strength than did uninformative ones despite higher rates of reinforcement on the uninformative alternative, both in a choice test and in a test that presented the events successively. The delay-reduction hypothesis of choice and conditioned reinforcement is consistent with results from the successive test but cannot account for the choice results. As the original study conducted the choice test following the successive test for all subjects, and as no reversals of the choice procedure were carried out, the present study replicated Pearce and Collins (1985) while controlling for order effects. Pigeons' relative rate of responding on the informative side was significantly greater in the successive procedure than in the choice procedure (as in the prior study); however, the uninformative side was significantly preferred to the informative side in the choice procedure when order of exposure to the two types of procedures was controlled. Both findings are consistent with the delay-reduction hypothesis.     

Self‐control in a Prisoner's Dilemma game: the role of trial spacing and an interfering task

Self‐control was studied in an iterated one‐player Prisoner's Dilemma game in which students' choices affected the payoff matrix on the next trial. The frequency of self‐control responses (choice of the smaller payoff now, but with the more generous payoff matrix more likely on the next trial) and defection responses (choice of the larger payoff now, but with the less generous payoff matrix more likely on the next trial) were measured. In Experiment 1, players achieved a criterion of five consecutive self‐control responses more quickly as a positive function of trial spacing, the presence between trials of a discriminative stimulus associated with the upcoming payoff matrix, and the probability that the self‐control or defection response would be reciprocated by the computer. Experiment 2 replicated the effect of trial spacing except when there was an interfering task during the interval, suggesting that trial spacing permits better appreciation of the contingencies. Copyright © 2006 John Wiley & Sons, Ltd.