Trading is such an activity when you should always be cold-blooded ... You should never give in to emotions, especially in this case 
Some wise people just said in this case that if you want to be a winner, you need to win the war of emotions while in a decision making scenario. So yes emotions are of the vital role that can make your decision a good one and a bad one too. No need to go for emotions. Try to avoid any such situation where emotions can overcome you. Trading has this situation many times so be vigilant.
Emotions should be eradicated in your trading. You should have the mindset of a general in the military where before they go to war, they should make it sure that they have already won the war - meaning, you must set a target price to buy and set target prices to sell and follow them strictly without any emotions on it.