  We present results of a programme of multi-epoch, intra-night optical
monitoring of a sample of non-blazar type AGN, which includes seven radio-quiet
QSOs (RQQs) and an equal number of radio-loud, lobe-dominated quasars (LDQs),
covering a redshift range from about 0.2 to 2.0. These two sets of optically
bright and intrinsically luminous QSOs are well matched in the redshift-optical
luminosity ($z - M_B$) plane. Our CCD monitoring covered a total of 61 nights
with an average of 6.1 hours of densely sampled monitoring of just a single QSO
per night, thereby achieving a typical detection threshold of $\sim 1$%
variation over the night. Unambiguous detection of intra-night
variability(INOV) amplitudes in the range 1$-$3% on day-like or shorter time
scales were thus made for both RQQs and LDQs. Based on these clear detections
of INOV, we estimate duty cycles of 17% and 9% for RQQs and LDQs, respectively;
inclusion of the two cases of probable variations of LDQs would raise the duty
cycle to 15% for LDQs. The similarity in the duty cycle and amplitude of INOV
for the RQQs and LDQs suggests, firstly, that the radio loudness alone does not
guarantee an enhanced INOV in QSOs and,secondly, that as in LDQs, relativistic
jets may also be present in RQQs. We argue that, as compared to BL Lacs, the
conspicuously milder, rarer and possibly slower INOV of RQQs and LDQs, can in
fact be readily understood in terms of their having optical synchrotron jets
which are modestly misaligned from us,but are otherwise intrinsically as
relativistic and active as the jets in BL Lacs.
