A direct comparison of our results with previous findings is difficult because of the many experimental differences among paradigms (the number of electrodes and electrode layout, the reference, baseline correction and the specific task settings). Despite these differences, there are consistent emerging observations: a sequence of early visual potentials, peaking at 100 ms (P1), 150 (N1) and 200 (P2), on the occipital electrodes relative to saccade offset (Jagla et al.,
2007; Thickbroom et al.,
1991; Yagi,
1981). Since it was a free eye movement task and we aligned our evoked potentials to the saccade offset (i.e., to the onset of the fixation), we expected the presaccadic potentials, i.e. the presaccadic spike (SP), the premotor negativity (PMN) and the premotor positivity (PMP) (Jagla et al.,
2007; Thickbroom & Mastaglia,
1985,
1990) to be somewhat blurred. In the PMN and PMP, since there was no fixed preparatory period and we also used the period between 200 ms and 100 ms before the saccade offset as baseline for averaging, we did not expect to see any deflection. Some previous studies have also shown late cognitive responses, mostly in reading (Marton & Szirtes,
1988a,
1988b). Interestingly, early markers of fixation content have been reported (Marton & Szirtes,
1988b). Marton and Szirtes (1988) presented a P370 or N370 that indexed if the last word of a sentence was correct or incorrect. These responses started to diverge at around 220 ms locked to saccade onset, thus near 160 ms after saccade offset, and comparable to our study (Marton & Szirtes,
1988b). Since in fixed gaze experiments in reading some effects of word frequency, context and semantic category have been described in early potentials such as N170 (Pulvermuller, Assadollahi, & Elbert,
2001; Scott, O'Donnell, Leuthold, & Sereno,
2009; Sereno, Brewer, & O'Donnell,
2003; Sereno & Rayner,
2003; Sereno, Rayner, & Posner,
1998; Skrandies,
1998), and these studies did not have a replay situation, it is impossible to discriminate if these early responses were characteristic of the eye movement situation or they were related to the spatial and temporal features of the statistical distribution of the stimuli. An important difference of our study is that we explicitly compared the evoked potentials during eye movements with a control in which we tried to match all variables while fixing eye-movement.