The left hand controls not only pitch, but also timbre. A pitch played on the A string can be played higher up the fingerboard on the D string, and even higher on the G and C strings. Shorter, thicker strings (high positions on the G and C strings) have fewer overtones and shorter decay. The reduced decay time is particularly noticeable for pizzicato, as shown in the video below.
C4 is plucked on each string, with a similar force and plucking direction. The overtone content is weaker and decay time is shorter on the lower strings. I dampened all of the strings that I wasn’t playing (firstly with the chin, then with the fingers of the left hand) to prevent resonance from the other strings interfering with the impression of decay time.