Everyday experience and psychology research both indicate that paying close attention to one thing can keep you from noticing something else.
However, a new study from the University of Wisconsin-Madison suggests that attention does not have a fixed capacity - and that it can be improved by directed mental training, such as meditation.
Seeing and mentally processing something takes time and effort, says psychology and psychiatry professor Richard Davidson of the UW-Madison School of Medicine and Public Health and the Waisman Center. Because a person has a finite amount of brainpower, paying close attention to one thing may mean the tradeoff of missing something that follows shortly thereafter. For example, when two visual signals are shown a half-second apart, people miss the second one much of the time.
"The attention momentarily goes off-line," Davidson says. "Your attention gets stuck on the first target, then you miss the second one." This effect is called "attentional blink," as when you blink your eyes, you are briefly unaware of visual signals.
But, he adds, the ability to occasionally catch the second signal suggests that this limitation is not strictly physical, but that it may be subject to some type of mental control.
Led by postdoctoral fellow Heleen Slagter, Davidson's research group in the Waisman Laboratory for Brain Imaging and Behavior recruited subjects interested in meditation to study whether conscious mental training can affect attention. "Meditation is a family of methods designed to facilitate regulation of emotion and attention," says Davidson.
The new study, which appears online May 8 in the journal PLoS Biology, examined the effects of three months of intensive training in Vipassana meditation, which focuses on reducing mental distraction and improving sensory awareness.
Volunteers were asked to look for target numbers that were mixed into a series of distracting letters and quickly flashed on a screen. As subjects performed the task, their brain activity was recorded with electrodes placed on the scalp. In some cases, two target numbers appeared in the series less than one-half second apart - close enough to fall within the typical attentional blink window.