The human brain has always had trouble perceiving and processing chains of events that happen very rapidly within seconds, or even within a single second. Researchers found that the brain can be trained so that switching attention from one object to the next can be done more quickly.
During accidents, for example, a person would notice the spinning car directly in front of him but he would not immediately notice the other car beyond it. This deficit in our attention is called “attentional blink” by psychologists. In order to overcome this deficit, Brown’s Department of Cognitive, Linguistic and Psychological Sciences professor, Takeo Watanabe, “One of the best ways to enhance our visual ability is to improve our attentional function.”
The study’s findings, published in the Proceedings of the National Academy of Sciences, reveal that by giving a second target object a distinct color, the brain can be trained to switch its attention from the first object to the second more rapidly; the brain would then be able to do the same thing with two objects that are presented in very quick succession even if the second object is not given a distinct color.
The researchers performed a simple experiment that involved showing participants a sequence of characters in rapid-fire succession: two white-on-black numbers interspersed among and spaced apart by many white-on-black letters. The character sequence was presented in two, different sets: one set had the numbers separated by only two letters, appearing a fifth of a second apart; the other set had the numbers separated by six letters, appearing half a second apart. The participants were asked to type the numbers they saw.
The results of the first part of the experiment showed that participants found it easier to remember the second number when it appeared much later after the first than when it was presented less than half a second after the first number. For the second part of the experiment, the researchers colored the second number red.
After training the participants with the colored second number, the researchers again showed them a sequence of only black and white characters. They found that they were able to remember the second number more often when shown the sequence where the two numbers were spaced less than half a second apart and almost as often as when shown the sequence where the two numbers were more than half a second apart. They repeated the experiment using the black and white sequence a few months later and found that the participants still retained the enhanced attentional function. The results were the same even when they varied the time interval between the first and second numbers and when they used gibberish instead of letters between the two numbers.
Watanabe explains, “A color change can be very conspicuous. If all items are black and white and all of a sudden a color item is show, you pay attentio to that.”
To further test their hypothesis, the researchers performed two more experiments. One experiment again involved a sequence of characters where the second target was not colored but it was shown to a different set of participants who did not undergo “training.” The last experiment involved yet another set of participants being shown a sequence of characters where the character immediately after the first number was colored red, whether it was the second target number or not, and the second target number appeared at different points in each sequence shown. In both experiments, the participants did not demonstrate any improvements in their attentional blink.
The authors concluded that the mere presence of color does not eliminate or diminish attentional blink; the brain can only be trained to spot a second target object more quickly when it is the second target object that is distinctly colored.
By using an fMRI, the researchers further proved, by the lack of resemblance between brain activity when target numbers appear close together and when they appear farther apart, before and after the participants were trained that that there was no improvement in the actual processing of the stimuli, rather, the training helped improve the brain’s ability to switch its attention more quickly from the first target to the second.