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Psychologist Nick Thompson and his students study how human behaviors--like the sounds babies make--have been selected over time to support individual survival. |
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White lies and baby cries
Professor Nick Thompson's research
Researchers in evolutionary psychologist* Nick Thompson's lab can often be found listening to crying babies. Why do babies' cries sound the way they do? Why do adults respond so readily? Go to an online interview with Thompson and undergraduates Kelly Ku '03 and Karen Webster '04 to learn more about their research into baby cries, or read below about the work of Thompson and former graduate students Brian Dessureau and Carolyn Olson.
Baby cries are a crucial means of communication between babies and their caregivers. If you've ever tried to stay calm around a baby who wouldn't stop crying, you know that babies can produce an impressive array of melodramatic sounds, including pants, shrieks, gasps and coughs. You also know those cries often inspire alarm, irritation and an urge to "do something" in the adult listener.
Thompson, Dessureau and Olson hypothesized that the gasps and coughs characteristic of a crying baby may sound to adults like respiratory distress. Scientists know that as an infant's vocal cords mature, the risk of choking increases. A need to be alert to breathing impairment might explain why a cry that sounds like respiratory distress is especially good at getting a caregiver's attention.
But Thompson's team also knows that this style of cry can occur when the baby needs attention for some other reason-perhaps a diaper change, a feeding, or companionship. So are these gasping and choking sounds always indicative of genuine respiratory distress (what Thompson's team called the "extortion theory") or could the baby be faking respiratory distress some of the time (the "deception" theory)? Which strategy would best insure infant survival?
The researchers used game theory to evaluate the distortion and deception theories. Game theory is a technique used by some social scientists to evaluate behavioral options and outcomes.
A classic example of game theory is called the Prisoners' Dilemma. In this scenario, two prisoners suspected of collaborating in a crime are interrogated separately by police. In an attempt to get the necessary proof, each suspect is told that freedom will be the reward for providing evidence against the other. Thus, each suspect has the option of informing on his or her partner, or remaining silent.
If you were one of the prisoners, your sentence would depend on what both you and your partner do. But you can't know in advance whether your partner will implicate you or remain silent. What choice, then, should you make? To decide, you'd need to examine all possible combinations of choices and assess the costs and benefits of each combination.
In the situation of the crying baby that appears to be in respiratory distress, game theory analysis helped Thompson's group evaluate the outcomes of behavioral options available to the baby and the caregiver. Like the prisoners above, the baby and caregiver must each make behavioral choices without knowing what the other will do. Is the baby in real respiratory distress when it cries, or is it faking? What if the caregiver doesn't attend to the baby when it cries? Will it die? Will it stop crying anyway? Would the caregiver's behavior be different if he or she were related to the baby?
Based on their analysis, the researchers concluded that the deception ("faking") hypothesis was the explanation more compatible with the baby's survival. Even though a crying baby may sound like it is taking its last breath, crying is not necessarily indicative of respiratory distress.
*Evolutionary psychologists study how human behaviors have been selected over time to support individual survival.
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Additional Resources
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Listen! |
 Baby cries prompt parents to take action.
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