A Call To Attention

How the brain filters information to focus on select stimuli,and other mysteries.

You are driving to work,the clamour of the hour interrupting the cheery morning show on your favourite FM channel. You hum along,making a mental note of things to do today and wondering whats for lunch at the cafeteria. Then,out of nowhere,a cow juts into your lane. You brake to a halt immediately,missing the animal by a hairs breadth. What just happened? You are no Michael Schumacher,and you were distracted to boot. But when the cow came into view,the reflexive attentional mechanism in your brain kicked in,saving the day. Attention is like breathingit is an automatic process,but you can also control it. When voluntary,it is called top-down or selective attention,and when automatic,it is known as bottom-up or reflexive attention, says Professor SP Arun,at the Centre for Neuroscience,Indian Institute of Science,Bangalore,who studies object recognition processes at work in humans.

First systematically studied by psychologist William James in the late-19th century,attention and its inner workings have been widely studied for their implications in learning and other higher-order cognitive functions like perception and memory. Attention by definition entails focusing on certain objects or thoughts at the cost of withdrawing focus from others. To put it simply,we have a limited capacity to process information,and attention is the gateway that regulates the inflow of sensory stimuli. Only some details of a stimulus will pass muster at the gates of attentionchances are,when you hit the brakes to save the cow,you didnt pause to note how many splashes of brown it had on its skin.

Attention is regulated by a network of areas in the brain,known as the attentional network,which includes portions of the parietal lobe,temporal cortex,frontal cortex and subcortical structures. Stimulant drugs used to treat attention deficit hyperactivity disorder,such as Ritalin,work by altering neuronal activity in some of these areas. But how exactly does attentional modulation occur? The answer,recent research suggests,does not lie only in increased neuronal activity. In a study on visual attention processes in monkeys published in Science in May 2009,researchers at the Massachusetts Institute of Technology concluded that when something catches our attention,the neurons in the prefrontal cortex,one of the brains chief control centres located in the front of the skull,oscillate synchronously at a high frequency,signalling the neurons in the visual cortex at the back of the head to pay attention. Furthermore,a 2007 paper by another research group at MIT states that distraction occurs at higher frequencies while sustained attention is characterised by lower-frequency oscillations. However,are changes in oscillatory activity the cause or effect of attention? How does the attentional network modulate the activity of other brain areasthrough changes in activity or changes in oscillatory activity? These issues still remain a topic of current research.

The interplay between voluntary and reflexive attention is portrayed best in what is called the cocktail party effect,which examines how,in a noisy gathering,one is able to pay attention to a whispered conversation with a friend,while also being susceptible to momentary distractionsan announcement or snatches of another conversation overheard,for instance. Of course,if that other conversation is particularly interesting,it may no longer be a momentary distraction,but the object of ones covert attentionthe very useful ability of being able to attend to something while not expressly directing ones attention to it. What causes an attentional shift such as this? A recent study at the University of Utah points to a region of the brain known as the intraparietal sulcus,which the researchers say contains a miniature map of the brains control regions. The control regions connect to the map and through this,facilitate a switch in attention from one task to another,the researchers say.

It is well established that when one pays attention to a task at hand,ones responses are quicker and more accurate,resulting in a performance better than when one wasnt paying attention. Some researchers,such as Clifford Nass at Stanford,have proposed that the digital revolution is making us lose the ability to focus by bombarding us with bursts of information like never before. Other scientists believe that since attention is a highly adaptable skill,it might even adapt to the demands of the digital revolution. You can train yourself to pay sustained attentionexperienced meditators have considerably longer attention spans than other people, says Professor Arun.

Almost every other study on attention throws up wildly varying and controversial results. A paper by researchers at the University of Rochester last year overturned previous conclusions on the harmful effects of gaming with its finding that video games high on action can improve visual attention. Another highly publicised study,an ongoing Harvard University initiative called The Happiness Project,has found that people spend 47 per cent of their waking time distracted,and as a result,are unhappy. In yet another study,one that is sure to delight many,researchers of psychology at the University of Illinois found that,counterintuitively,brief diversions from the task at hand serve to improve attention. Most results from studies on attention,a process so hard to pin down,tend to be highly task-specific. For example,taking a break from a demanding task can serve as rest and therefore improve task performance,but taking too many breaks from a simple task may impair performance. Thats why these soundbites should be taken with a pinch of salt,says Professor Arun.

Fortunately for us,there is one heartening result that does seem to hold true. If our reflexive attention is grabbed by a sensory stimulus in the environment,chances are we wont be distracted by it for more than a couple hundred milliseconds. Unless we are looking at Justin Bieber doing the moonwalk,in which case our intelligent,automatic orienting system gives in to the ludicrous ways of our voluntary attentional disposition.