Quoted from the paper itself.
The Relative Power of Negativity: The Influence of Language Intensity on Perceived StrengthNegative utterances and words have been found to be stronger than positive utterances and words.
The negativity effect can be explained with the help of cognitive psychological research that showed negative utterances are perceived as stronger than positive ones. Negative utterances get more attention, arouse more emotions, have more influence on recipient behavior, and are stored better and longer in memory.
The strong effects of negativity are powerful for evolutionary reasons. Because negativity is often associated with fear or danger, and positivity with security and safety, at a cognitive level, a person automatically pays more attention to unpleasant (negative) than to pleasant (positive) information. This psychological phenomenon is called the
Negativity bias.