Sequential effect and temporal orienting in pre-stimulus oculomotor inhibition

When faced with unfamiliar circumstances, we often turn to our past experiences with similar situations to shape our expectations. This results in the well-established sequential effect, in which previous trials influence the expectations of the current trial. Studies have revealed that, in addition to the classical behavioral metrics, the inhibition of eye movement could be used as a biomarker to study temporal expectations. This pre-stimulus oculomotor inhibition is found a few hundred milliseconds prior to predictable events, with a stronger inhibition for predictable than unpredictable events. The phenomenon has been found to occur in various temporal structures, such as rhythms, cue-association and conditional probability, yet it is still unknown whether it reflects local sequential information of the previous trial. To explore this, we examined the relationship between the sequential effect and the pre-stimulus oculomotor inhibition. Our results (N=40) revealed that inhibition was weaker when the previous trial was longer than the current trial, in line with findings of behavioral metrics. These findings indicate that the pre-stimulus oculomotor inhibition covaries with expectation based on local sequential information, demonstrating the tight connection between this phenomenon and expectation and providing a novel measurement for studying sequential effects in temporal expectation.