Inattentive schoolchildren performed significantly better when white noise was played during class, results of a small study showed.
The background noise had the opposite effect on normally attentive children, whose classroom performance deteriorated.
The study produced no evidence that background noise had a beneficial effect on hyperactivity, investigators reported online in Behavioral and Brain Functions.
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"This finding could have practical applications, offering noninvasive and nonpharmacological help to improve school results in children with attentional problems," Göran B.W. Söderland of Stockholm University in Sweden said in a statement.
A large volume of experimental and clinical evidence has demonstrated that cognitive processing is readily disturbed by distracting environmental stimuli. Some people, such as individuals with attention deficit/hyperactivity disorder (ADHD), are especially vulnerable to distraction, the authors noted.
However, some investigators have reported contradictory findings, showing that certain task-irrelevant noise can improve performance in children with attention deficits.
The explanation for the paradoxical effects of background noise remains unclear. One line of thought holds that background stimulation leads to increased arousal, which counteracts boredom.
Another model relies on principles of stochastic resonance, or noise-improved signaling, the authors continued. Detection of sensory signals offers one example. A weak signal or tone stimulus that is below the hearing threshold becomes detectable when random noise is added to the signal.
The theory of stochastic resonance also holds that the effects vary among individuals. The differences are linked to attention ability and neurotransmission in such a way that inattentive people require more external noise for proper cognitive function, the authors added.
ADHD is distinguished by low tonic dopamine levels that result in excessive reactivity to environmental stimuli. The moderate-brain-arousal model suggests that the dopamine-poor brain requires higher input noise to function to full potential. External white noise might compensate for behavior dysfunction related to impaired dopamine transmission.
Extending research into the association between noise and cognitive performance, the authors examined the effects of white noise on performance in a normal group of children who differed in their attentiveness.
The study involved 51 secondary-school students, whose classroom attention level had been rated by teachers. The students completed a verbal-recall test with and without the presence of auditory background noise.
The authors found a statistically significant positive correlation between attention and noise. Moreover, they found that the positive effect of noise increased with a student's inattention score and the negative effect increased with higher scores for attention.
The analysis also showed a significant negative correlation between reading skill and a positive effect of noise, a positive correlation between attention and reading ability, and a positive correlation between teacher-rated inattention and hyperactivity. The authors found no correlation between hyperactivity and noise-effect.
"Our data show that auditory white noise may exert potentially similar effects on cognition as medication through the phenomenon of stochastic resonance," the authors wrote in their discussion. "White noise is characterized by randomness and so introduces variability in the nervous system. A poorly tuned neural system benefits from additional white noise."
The authors noted that one limitation of the study is that only two levels of noise were evaluated. "One prediction from our model is that in [the] attentive group, a subset of participants will benefit from noise when levels are individually adjusted," they noted.
Another limitation is that only one test of cognitive ability was given, and it is not known if the effects would generalize to other cognitive measures.