Optically induced breaking of symmetries plays an important role in nonlinear photonics, with applications ranging from optical switching in integrated photonic circuits to soliton generation in ring lasers. In this work we study for the first time the interplay of two types of spontaneous symmetry breaking that can occur simultaneously in optical ring resonators. Specifically we investigate a ring resonator (e.g. a fiber loop resonator or whispering gallery microresonator) that is synchronously pumped with short pulses of light. In this system we numerically study the interplay and transition between regimes of temporal symmetry breaking (in which pulses in the resonator either run ahead or behind the seed pulses) and polarization symmetry breaking (in which the resonator spontaneously generates elliptically polarized light out of linearly polarized seed pulses). We find ranges of pump parameters for which each symmetry breaking can be independently observed, but also a regime in which a dynamical interplay takes place. Besides the fundamentally interesting physics of the interplay of different types of symmetry breaking, our work contributes to a better understanding of the nonlinear dynamics of optical ring cavities which are of interest for future applications including all-optical logic gates, synchronously pumped optical frequency comb generation, and resonator-based sensor technologies.Passive nonlinear optical cavities have been studied extensively in the past decades, partly for their ability to increase the efficiency of light-matter interactions through a large enhancement of circulating power [1]. Quite recently, the interest was renewed after the first observation of so-called cavity solitons (stable pulses of light circulating inside a resonator indefinitely) in macro-scaled fiber loops [2] and microresonators [3], underpinning the generation of Kerr frequency combs [4]. In a number of practical studies, such systems are not driven by a continous wave (cw) laser but rather pumped by a train of pulses so that comparatively greater input peak powers are achieved [5][6][7] or to generate solitons and frequency combs with an improved efficiency [8]. This however requires a rigorous control of either the pulse train repetition rate or cavity length to ensure the synchronicity of the pumping, the lack of which might alter the dynamics of the system [9,10].Several studies have focussed on a scenario where the input pulses are Gaussian and their duration is longer than that of a typical cavity soliton. In that case, it has been observed that, provided that the resonator exhibits anomalous dispersion, the peak of the intracavity pulse does not necessarily lock at an extremum of the input power (symmetric solution). Instead, a solution where the peak of the soliton is shifted with respect to the extremum seems to be favoured. This phenomenon is referred to as a spontaneous symmetry breaking of the temporal pulse profile [11][12][13][14] and has been very recently identified in the context of cavity soliton dy...