  To investigate the link between weak tidal interactions in disk galaxies and
the boosting of their recent star formation, we obtain images and spatially
integrated spectra (3615A < lambda < 5315A) for 40 late-type spiral galaxies
(Sab-Sbc) with varying degrees of lopsidedness (a dynamical indicator of weak
interactions). We quantify lopsidedness as the amplitude <A_1> of the m=1
Fourier component of the azimuthal surface brightness distribution, averaged
over a range of radii. We compare the young stellar content, quantified by
EW(H\delta_abs) and the strength of the 4000 Angstrom break (D_4000), with
lopsidedness and find a 3-4 sigma correlation between the two. We also find a
3.2 sigma correlation between EW(H\beta_emission) and lopsidedness. Using the
evolutionary population synthesis code of Bruzual & Charlot we model the
spectra as an ``underlying population'' and a superimposed ``boost population''
with the aim of constraining the fractional boost in the SFR averaged over the
past 0.5 Gyr (the characteristic lifetime of lopsidedness). From the difference
in both EW(H\delta_abs) and D_4000 between the most and least symmetric thirds
of our sample, we infer that ~ 1x10^9 M_solar of stars are formed over the
duration of a lopsided event in addition to the ``underlying'' SFH (assuming a
final galactic stellar mass of 10^10 M_solar). This corresponds to a factor of
8 increase in the SFR over the past 5x10^8 years. For the nuclear spectra, all
of the above correlations except D_4000 vs. <A_1> are weaker than for the disk,
indicating that in lopsided galaxies, the SF boost is not dominated by the
nucleus.
