Strangely there comes with the abstraction of BW a certain loss of time-context; that is, somehow in color there is a certain presumption that the moment of shutter release is contemporary to our own moment of viewing. Conversely with BW there is more psychological distance between shutter release and experience of viewing. So in BW it becomes relatively easy to imagine the moment captured was generations ago, or just as easily today. By the same logic of time-out-of-time the BW image could even be imagined as a portent of a future moment.
What is it about color that leads to the presumption of present-day immediacy, I wonder: the fact that color technology only became commonplace in the middle or later 1960s, but that hair styles and clothing fashions, design of interiors, cars and building facades all can date the image, even when presented in color. These same material cues somehow seem less insistent when the default assumption is that BW means the subject is temporally separated from our own time.
There is also an age-of-viewer effect: a youthful person may have a month to month time scale, but a middle-aged person may be accustomed to taking in the changes in people, economy, organizational life cycles, etc of 2-5 year time horizons. And an elderly person may feel as though peering through a telescope, collapsing the decades now gone and projecting the decades yet to come into a single, long view.