Microaggression is a topic that does not receive anything close to the current focus upon bullying and cyberbullying in the media.  Still, there is research indicating that microaggression can be very detrimental to recipients of it.
Derald Wing Sue, a psychologist at Columbia University, defines microaggression as everyday slights and insults that minority persons and marginalized groups encounter.  Persons who enact microaggression often are unaware of their behaviors—the behaviors are revelatory of unconscious bias and are often outside of our awareness.  Also, on the surface, microaggressions can seem benign, innocent, and complimentary, yet there are veiled metamessages that are often demeaning and patronizing.
Let’s look at some examples of this:
1) A Caucasian woman states to an African-American teenager, “Wow, you are so bright!  I can’t believe how bright and articulate you are!” 
2) A Caucasian professor indicates to his third generation, Asian-American student:  “I’m very impressed with your English, you speak so fluently!”
3) A female executive in a pharmaceutical company is ignored during a contentious meeting, for the most part filled with white, male executives.
4) Wendy Bell, the former local newscaster, exclaiming to the manager of an African-American restaurant worker, “I wonder how long it had been since someone told him he was special.”
In the first example, the essential metamessage is that it is atypical or unique for an African-American teenager to be bright and articulate.  In the second, that Asian-Americans, even third generation Asian-Americans, typically have a tenuous grasp of English.   In the third, the female executive is rendered invisible by her male colleagues, as her discourse is interrupted and cut short.  Ms. Bell, in the fourth example, was filled with unreflective, patronizing, and demeaning discourse toward the restaurant worker.  As if only from her perspective is one able to deliver legitimate praise to the worker.
In Dr. Sue’s research, he finds that microaggressions, at times, can be more harmful than outright racism, as the slights are subtle and not easily detectible, yet simultaneously demeaning and psychologically damaging, as they can lead to confusion and anger.  They are confusing as one is being complimented and insulted in the same breath!
From Dr. Sue’s perspective, we should be vigilant about our biases and not exhibit defensiveness if another calls our attention to bias or microaggression.  Further, we should be open to changing our attitudes and beliefs.