Sensation, which by its very nature is dependent on the object and on objective stimuli, undergoes considerable modification in the introverted attitude. It, too, has a subjective factor, for besides the sensed object there is a sensing subject who adds his subjective disposition to the objective stimulus.
Jung defines sensation as inherently object-dependent yet modified by a subjective component in the introverted attitude, establishing the dual character of the sensation function.
, Psychological Types, 1921thesis