It is pointed out that the Wigner function
f(r,p) is
h2 times the expectation value of the parity operator that performs reflections about the phase-space point
r,
p. Thus
f(r,p) is proportional to the overlap of the wave function $\ensuremath{\psi}$ with its mirror image about
r,
p; this is clearly a measure of how much $\ensuremath{\psi}$ is centered about
r,
p, and the Wigner distribution function now appears physically more meaningful and natural than it did previously.