Target-distractor competition cannot be resolved across a saccade

Abstract

When a distractor is presented in close spatial proximity to a target, a saccade tends to land in between the two objects rather than on the target. This robust phenomenon (also referred to as the global effect) is thought to reflect unresolved competition between target and distractor. It is unclear whether this landing bias persists across saccades since a saccade displaces the retinotopic representations of target and distractor. In the present study participants made successive saccades towards two saccadic targets which were presented simultaneously with an irrelevant distractor in close proximity to the second saccade target. The second saccade was either visually-guided or memory-guided. For the memory-guided trials, the second saccade showed a landing bias towards the location of the distractor, despite the disappearance of the distractor after the first saccade. In contrast, for the visually-guided trials, the bias was corrected and the landing bias was eliminated, even for saccades with the shortest intersaccadic intervals. This suggests that the biased saccade plan was remapped across the first saccade. Therefore, we conclude that the target-distractor competition was not resolved across a saccade, but can be resolved based on visual information that is available after a saccade.

Visual information is required to reduce the global effect

“…While the persistence of the global effect in double-step saccades (Arkesteijn et al, 2018) could have been because participants had preprogrammed a saccade, this explanation was not supported by results obtained in the present study. The similarity of the time course of the global effect in the conditions when the identity of the target was known in advance or only revealed later is remarkable.…”

“…These results are consistent with a previous study (Arkesteijn et al 2018), where a global effect was found in a double-step memory-guided saccade, together with a sustained global effect as a function of saccade latency. The magnitude of the global effect for the double-step memoryguided saccades was smaller than for the single memoryguided saccades reported here (8% bias in the direction of the distractor in the previous study, compared with 20% bias reported in the present study).…”

“…The target-distractor competition was updated across the first saccade, and the size of this global effect did not change following longer saccade latencies. Thus, even though the global effect declines with saccade latency in visually guided saccades (Heeman et al, 2014;Ottes et al, 1985), it was not the case when the target was memorized (Arkesteijn et al, 2018).…”

“…Even though the global effect has been consistently found to disappear when saccade latencies were longer than approximately 300 ms (Heeman et al, 2014;Ottes, Van Gisbergen, & Eggermont, 1985), a recent study showed that it does not reduce when participants had to keep the target in memory across a saccade (Arkesteijn et al, 2018). In Arkesteijn et al (2018) participants had to execute two consecutive saccades while the second saccade target had to be kept in memory. The target-distractor competition was updated across the first saccade, and the size of this global effect did not change following longer saccade latencies.…”

“…Coren and Hoenig (1972) were the first to accurately describe this phenomenon and to point out that when observers have to make an eye movement to a target stimulus surrounded by irrelevant stimuli, the eyes tend to land on the center of gravity of all stimuli. This tendency to saccade towards the intermediate position between a target and a distractor is currently referred to as the global effect (Findlay, 1982; see also, e.g., Arkesteijn, Smeets, Donk, & Belopolsky, 2018;Coëffé & O'Regan, 1987;Van der Stigchel & Nijboer, 2011).…”