Can you explain what this prompt is asking me, and also what the quote means?

Can you explain what this prompt is asking me, and also what the quote means?  :

In a section entitled “The Power of Context,” Gladwell cites a study that suggests that “the convictions of your heart and the actual contents of your thoughts are less important, in the end, in guiding your actions than the immediate context of your behavior.” 

Consider this remark about what determines human behavior. Then write an essay that defends, challenges, or qualifies Gladwell’s assertion. Support your argument with appropriate evidence from your reading, observation, and/or experience. (You may choose evidence from Gladwell for one piece of evidence).