Placeholder objects shape spatial attention effects before eye movements

Abstract

In the time leading up to a saccade, the saccade target is perceptually enhanced compared to other objects in the visual field. This enhancement is attributed to a shift of spatial attention toward the target. We examined whether the presence of visual objects is critical for the perceptual enhancement at the saccade target to occur. We hypothesized that attention may need an object to focus on in order to be effective. We conducted four experiments using a dual-task design, where participants performed eye movements either to a location demarked by a placeholder or to an empty screen location where no object was displayed. At the same time, they discriminated a probe flashed at the location targeted by the eye movement or at one of two control locations. A strong perceptual advantage at the saccade target location was observed only when placeholders were displayed at the time of probe presentation. The complete absence of placeholders (Experiment 1), the presence of placeholders before but not during probe presentation (Experiment 3), and the presence of objects only around the saccade target (Experiments 3 and 4) led to a strong reduction in the saccade-target benefit. We conclude that placeholders may indeed be necessary to observe presaccadic enhancement at the saccade target. However, this is not because placeholders provide an object to focus attention on, but rather because they produce a masking (or crowding) effect. This detrimental effect is overcome by the presaccadic shift of attention, resulting in heightened perception only at the saccade target object.

A dynamic 1/f noise protocol to assess visual attention without biasing perceptual processing

“…This demonstrates that visual structures pose the risk of compromising the attention measurement in a non-systematic way. In line with previous work showing the impact of placeholder objects on attentional modulations of visual perception (Taylor et al, 2015; Puntiroli et al, 2018; Szinte et al, 2019), these findings underline the necessity of an unbiased, item-free approach to map perceptual dynamics across the visual field in the absence of object-like structures.…”

“…However, these conventional approaches face a common shortcoming: They all rely on localized test stimuli to determine the deployment of visual attention. The potential problem with this approach is that these stimuli could bias visual perception by structuring the visual field (Taylor, Chan, Bennett, & Pratt, 2015; Puntiroli, Kerzel, & Born, 2018; Szinte, Puntiroli, & Deubel, 2019; Shurygina, Pooresmaeili, & Rolfs, 2021) and may thus affect what they are intended to measure – the spatial distribution of attention. In a paradigm using a typical stimulus configuration as displayed in Figure 1A , attention is likely biased towards the presented stimuli (as compared to locations in between or further in- or outside), since those are the only locations containing potentially task-relevant visual information ( Figure 1B ).…”

The spread of presaccadic attention depends on the spatial configuration of the visual scene

“…While our findings match those of studies which investigated the allocation of attention with a continuously presented cue 6,13,14,18,20,22,23,30,31 , these studies were all using a structured visual field of visual placeholders. Puntiroli and colleagues 21 is to our knowledge the only study in which the effect of visual placeholders on the presaccadic shift of attention was investigated. They measured the relative performance in discriminating a cross displayed at three possible placeholders, the saccade target and two distractors, either present or absent of the screen in different blocks of trials.…”

“…But, do these effects reflect the precision of the spatial deployment of the presaccadic shift of attention or the use of a structured visual scene for their assessment? Puntiroli and colleagues 21 recently tested the influence of a structured visual field composed of several placeholders on the deployment of attention. They observed that the presaccadic shift of attention reduces potential masking effects that flankers can have on the saccade target.…”

Location-cued visual selection—Placeholder dots improve target identification

“…They may act as ''anchors'' that help direct attention to certain locations or regions (Jefferies & Di Lollo, 2015), to objects (Egly, Driver, & Rafal, 1994), or to groups of objects (Dodd & Pratt, 2005). They improve the accuracy of gazed-at locations (Wiese, Zwickel, & Müller, 2013) and generally shape the focus of spatial attention before and during eye movements (Lisi, Cavanagh, & Zorzi, 2015;Puntiroli, Kerzel, & Born, 2018). What appears surprising, however, is the reported differential effect of placeholders on facilitatory and inhibitory attentional modulations.…”