By stimuli that we can perceive, I mean what our five senses can perceive.

Is there an absolute minimum for humans, or can we "train" ourselves to perceive stimuli in lower values?

And if there is an absolute minimum, do we know what it is?

By stimuli that we can perceive, I mean what our five senses can perceive.

Is there an absolute minimum for humans, or can we "train" ourselves to perceive stimuli at lower intensity?

And if there is an absolute minimum intensity, do we know what its value is?