1A series of recent studies suggested that eye movements are linked to temporal predictability. 2 In these studies, temporal predictability was manipulated by setting the interval between a cue 3 and a target (foreperiod) to be either fixed or random, in separate blocks. Findings showed that 4 shortly prior to target onset, oculomotor behavior was reduced in the fixed relative to the 5 random condition. This effect was interpreted as reflecting the formation of temporal 6 expectation. However, it is still unknown whether the effect is driven by target-specific 7 temporal orienting (orienting hypothesis), or whether it is a result of a more general and 8 context-dependent state of certainty that participants may experience during blocks with a high 9 predictability rate (certainty hypothesis). 10 In the following study we examined this question by dissociating certainty and 11 orienting. In each trial, a temporal cue (fixation color change) was followed by a slightly tilted 12 grating-patch, on which participants made tilt-discrimination decision. The distribution of the 13 foreperiods was varied between blocks to be either fully fixed (100% of trials with the same 14 foreperiod), mostly fixed (80% of trials with one foreperiod and 20% with another) or random 15 (five foreperiods in equal probabilities). The two hypotheses led to different prediction models 16 which were tested against the experimental data.
17Results were highly consistent with the orienting hypothesis and inconsistent with the 18 certainty hypothesis, supporting the link between oculomotor inhibition and temporal orienting 19 and its validity as a marker for target-specific expectations in future studies. 20 21 attention 23 24 26Temporal expectation is a prediction regarding the timing of events based on 27 previously-experienced temporal regularities (Nobre & van Ede, 2017). Recent studies showed 28 that the oculomotor system is tightly linked to temporal attention and expectation: oculomotor 29 activity (saccades, ocular drift, and blinks) is inhibited for a few hundred milliseconds prior to 30 the appearance of a predictable, relative to an unpredictable, stimulus (Abeles et al., 2020; Amit 31 et al., 2019; Badde et al., 2020; Dankner et al., 2017; Denison et al., 2019). This oculomotor 32 inhibition phenomenon can be used as a sensitive marker for temporal expectation and, as such, 33 has several advantages over traditional behavioral and electrophysiological markers (Amit et 34 al., 2019). Oculomotor inhibition prior to a predictable target was found to occur with various 35 types of temporal structures: with rhythmic expectations, when stimuli were predictable 36 because they are part of a rhythmic stream of stimulation (Dankner et al., 2017), and with 37 associative expectations, when targets are rendered predictable by a precedent informative 38 temporal cue in a visual (Amit et al., 2019), auditory (Abeles et al., 2020) or tactile (Badde et 39 al., 2020) task. Oculomotor inhibition was also hypothesized to be modulated by c...