Advantage & Disadvantages of Attention
 Advantages:   The advantages of attention are relatively clear. By paying attention,  a  person in able to place information in working memory storage. By   placing information into a working memory storage the person is able to   recall this information when needed.
 Disadvantages:   A person has a limited capacity for attention. "Psychologists proposed   that people can pay attention to only one thing at a time." (Ormrod,   2008, p. 175)
For example: The Peter-Paul goblet.
Early   Gesalt psychologists developed the theory that a person can only pay   attention to one object at a time. Carefully inspect this picture, does   your attention focus on the goblet or the two faces?
Another   disadvantage to attention is that many people have problems with   attention due to excessive active or impulsiveness. (Barkley &   Murphy, 2006) Attention-deficit hyperactivity disorder is a disorder   that psychologists are just starting to fully understand. Most children   are diagnosed with ADHD at an early age. Treatment options for ADHD  vary  depending on the severity of the disorder, ranging from  medications to  counseling.
Here is a link to the  Children and Adults with Attention Deficit/Hyperactivity Disorder  (CHADD) magazine, it is very informative-  http://www.chadd.org/Content/CHADD/AttentionMagazine/default.htm
Also, here is a link to the Attention Deficit Disorder Association website-http://www.add.org/site/PageServer
Reference
Barkley, R. & Murphy, K. (2006). Attention-Deficit Hyperactivity Disorder (3rd ed.). Guilford         Publications: New York, NY.
Ormrod, J. (2008). Human Learning (5th ed.). Pearson: Upper Saddle River, NJ.