  We carried out a multi-colour time-series photometric study of six stars
claimed as "hybrid" p and g mode pulsators in the literature. Gamma Peg was
confirmed to show short-period oscillations of the Beta Cep type and
simultaneous long-period pulsations typical of Slowly Pulsating B (SPB) stars.
  From the measured amplitude ratios in the Stromgren uvy passbands, the
stronger of the two short period pulsation modes was identified as radial; the
second is l=1. Three of the four SPB-type modes are most likely l=1 or 2.
Comparison with theoretical model calculations suggests that Gamma Peg is
either an 8.5 solar mass radial fundamental mode pulsator or a 9.6 solar mass
first radial overtone pulsator. HD 8801 was corroborated as a "hybrid" Delta
Sct Gamma Dor star; four pulsation modes of the Gamma Dor type were detected,
and two modes of the Delta Sct type were confirmed. Two pulsational signals
between the frequency domains of these two known classes of variables were
confirmed and another was newly detected. These are either previously unknown
types of pulsation, or do not originate from HD 8801. The O-type star HD 13745
showed small-amplitude slow variability on a time scale of 3.2 days. This
object may be related to the suspected new type of supergiant SPB stars, but a
rotational origin of its light variations cannot be ruled out at this point. 53
Psc is an SPB star for which two pulsation frequencies were determined and
identified with low spherical degree. The behaviour of 53 Ari and Iota Her is
consistent with non-variability during our observations, and we could not
confirm light variations of the comparison star 34 Psc previously suspected.
The use of signal-to-noise criteria in the analysis of data sets with strong
aliasing is critically discussed.
