What does backwards in sentiment mean

The meaning of the phrase, "backwards in sentiment" is reluctant to show emotions and the sentimental feelings are not very well developed. This is used to refer to the persons or other species who are not very much affected with the past emotional events.

in sentiment, backwards mean: Hard to show emotion, sentimental feelings are undeveloped. In most cases, this type of behavior is diplayed by introverted person. These group of people feel drained simply by socializing with other people and need a lot of free time for themselves to be able to fully function.