Do you feel that white people generally have dry reaction/less expressive compared to black people?

In my experience, culture is the determining factor in such comparisons.

I don’t believe that it is race related but rather a cautionary response from any group. Obviously
it depends on life experiences that each person had in their past that now shows up as caution or in inexperienced people a lack of wariness as a warning of danger.

It is culture based, just like some cultures would not understand vaudeville slap stick humor.

I think it’s a matter of personality more than anything. My sister is an extrovert, and her reaction to everything is large and effusive. I’m an introvert, and mine is just the opposite.

And need I add, we are of the same color (and share a lot of genes) and the same culture, born in the same hospital and growing up in the same house.

I haven’t found such generalizations about groups of people to be very useful, and the larger the group, the less useful the generalization. The most applicable statement about white people is that their skin pigmentation is generally lighter than that of black people, and even that isn’t reliable on an individual basis.

I happen to be reading Michelle Obama’s book at present, and the personality differences between her and her husband are striking. Their reactions to things reflects those differences much more than their race.

I agree that it could be the product of personality and/or culture but when it appears that the majority of a certain group of people have the propensity do such a thing what does it tell us? Can we blame other people who make assumption based on the number of repeated behavior shown by a certain group of people?

Lift one leg while standing, and stick out your tongue.
My sociology teacher told us this was a learned reaction, showing surprise in some Asian areas.
It’s cultural.

Maybe we examine our own perceptions, especially if others don’t share our view of “the majority of a certain group of people.” And maybe we examine our classification skills.

You might notice the more expressive people in any group more than the quiet ones and think they’re in the majority just because they attract more attention. That tends to happen in a lot of groups, not just racial ones.

There is such a thing as cultural traits or culturally reinforced traits, behaviors that are expressed in relatively high frequency within certain groups, such as friendliness or thriftiness. With respect to expressive behavior, I would argue that your grouping is wrong: it’s not black people or white people, but people who tend to be expressive rather than restrained or analytical. That is to say, the group with those traits is the group with those traits.

I have had numerous occasions when I needed assistance in some small way from a stranger.
In my experience, persons of any color shade hue have stepped up.
I remember when I left the Navy, I intended to live in Baltimore. Friends black and white feared for my safety, and urged me to live somewhere else.
Still new to Baltimore, I approached a subway terminal for the very first time. A black man probably in his early twenties noticed me, and saw my confusion. He explained how to use my pass in the turnstiles, when to ask bus drivers for transfers, the whole mass transit experience! He wished me luck, and went on his way.

I feel approach is 90% of outcome with most anybody. The trick is knowing what approach to use with whom.

Approaching that group of women from behind, then offering a kiss was an act doomed from the start.
Approaching any stranger should be done face to face.