A third possible reason why we did not find inflation is that in our study both the central and the peripheral stimulus were attended. Spatial attention can make detection criterion more conservative, potentially explaining (at least in part) the subjective detailed impression of the entire visual scene, as typically little attention is paid to the periphery (
Rahnev et al., 2011). In fact, previous studies reporting inflation have some component of inattention or positional uncertainty involved. For their detection task,
Solovey and Colleagues (2015) cued both the central and the peripheral locations, and the stimulus to detect had a 50% chance to show up at either location.
Li and Colleagues (2018) explicitly compared perceptual performance between attended and unattended peripheral locations and found more liberal criteria for the unattended locations. In the Odegaard et al. study (
2018), spatial attention is potentially impaired because of the positional uncertainty implied by the effect of crowding (
Strasburger et al., 2011). We speculate that both perceptual and metacognitive factors may play a role in explaining the perceived uniformity of the visual field. Inflation could play a major role for unattended locations, whereas attention would require filling out peripheral location with information at fixation (
Toscani et al, 2017). Our results suggest that we do not experience peripheral vision richer because of a metacognitive bias; we actually know that peripheral vision is poor. The perceived richness of peripheral vision and uniformity of the visual scene is probably due to perceptual mechanisms, at least for attended peripheral regions. Trans-saccadic integration helps to build a uniform visual scene by integrating the information from the same spatial position but different retinal locations (e.g.,
Ganmor, Landy, & Simoncelli, 2015;
Wolf & Schütz, 2015;
Herwig & Schneider, 2014;
Herwig, Weiß, & Schneider, 2015). This mechanism may add the richness of central vision to peripheral vision only to the locations which are seen peripherally and centrally in two different moments, typically when we direct a saccade to something we first saw in our peripheral vision. In natural vision we do not systematically sample the full visual scene; rather, we focus on task relevant elements and keep the rest in peripheral vision (
Hayhoe, 2000;
Hayhoe, Shrivastava, Mruczek, & Pelz, 2003;
Schütz, Braun, & Gegenfurtner, 2011). In these circumstances other mechanisms could yield the richness of peripheral vision by adding the missing details. Postsaccadic foveal feedback recalibrates the perception of size between the center and periphery (
Bosco, Lappe, & Fattori, 2015;
Valsecchi & Gegenfurtner, 2016). This recalibration mechanism probably happens because the visual system learns the contingency between peripheral stimulation and how this stimulation would be viewed centrally. Another mechanism is to fill out peripheral vision with perceptual information from central vision. There is evidence that the visual system propagates the brightness at fixation to influence the brightness of areas in the periphery (
Toscani et al., 2017). Crucially, this mechanism is selectively applied within an object's boundary, where it is reasonable to assume a certain continuity between central and peripheral brightness. Observers tend to fixate the objects at locations that yield the most diagnostic information when estimating lightness and brightness (
Toscani, Valsecchi, & Gegenfurtner, 2013a,
2013b;
Toscani, Zdravkovic, & Gegenfurtner, 2016), so it makes sense that the information gathered at the fixated location is filled out to the less diagnostic locations.