SCIENCE NOTEBOOK

Nearly half raised their heads upon hearing an alarm call, and many began to run. But only 28 percent responded to the songs.

Unknown is whether the iguanas are born with an appreciation of mockingbird alarms or learn their value later, the researchers reported in last week's online edition of Biology Letters, a publication of the Royal Society.

But the trick makes a lot of evolutionary sense, they concluded. Evasive maneuvers are energetically expensive and are best reserved for when they are really needed. And even among the dumb, audible signals are in many ways ideal because they can travel long distances without a line of sight.

-- Rick Weiss

Parental Variance Can Help Children

Contrary to what a lot of parents might think, it may not be the best thing for mothers and fathers always to react identically when dealing with their children's tantrums, according to new research.

Nancy L. McElwain of the University of Illinois at Urbana-Champaign and her colleagues interviewed 55 kindergarteners to assess their understanding of emotions, observed 49 preschoolers interacting with friends during two play sessions, and assessed how their parents reacted when the children displayed negative emotions, such as becoming anxious or upset about losing a favorite toy.

When one parent provided little support in response to a child's anger or anxiety and the other parent provided a lot, the child had less conflict with friends and understood its own emotions better, they found. In contrast, when both parents provided a lot of support, the child had less insight and experienced more conflict with peers.

Based on the findings, the researchers concluded that when both parents support a child's negative feelings, they may shield the child from learning about and managing those emotions.

McElwain reported the findings in the September-October issue of the journal Child Development.

"By moving beyond a 'mother-only' model and examining the joint contributions that mothers and fathers make to their children's well-being, researchers, clinicians, and early childhood educators will be better positioned to design and implement interventions aimed at fostering healthy social and emotional development," McElwain wrote.

-- Rob Stein