Asymmetric representations of upper and lower visual fields in egocentric and allocentric references

Abstract

Two spatial reference systems, i.e., the observer-centered (egocentric) and object-centered (allocentric) references, are most commonly used to locate the position of the external objects in space. Although we sense the world as a unified entity, visual processing is asymmetric between upper and lower visual fields (VFs). For example, the goal-directed reaching responses are more efficient in the lower VF. Such asymmetry suggests that the visual space might be composed of different realms regarding perception and action. Since the peripersonal realm includes the space that one can reach, mostly in the lower VF, it is highly likely that the peripersonal realm might mainly be represented in the egocentric reference for visuomotor operation. In contrast, the extrapersonal realm takes place away from the observer and is mostly observed in the upper VF, which is presumably represented in the allocentric reference for orientation in topographically defined space. This theory, however, has not been thoroughly tested experimentally. In the present study, we assessed the contributions of the egocentric and allocentric reference systems on visual discrimination in the upper and lower VFs through measuring the manual reaction times (RTs) of human subjects. We found that: (a) the influence of a target's egocentric location on visual discrimination was stronger in the lower VF; and (b) the influence of a target's allocentric location on visual discrimination was stronger in the upper VF. These results support the hypothesis that the upper and lower VFs are primarily represented in the allocentric and egocentric references, respectively.

Anatomic and functional asymmetries interactively shape human early visual cortex responses

“…asymmetries across the visual field. It has long been known that there are anatomic and functional differences between the upper and lower parts of the visual field (Hansen et al, 2016;Skrandies, 1987;Zhou et al, 2017;Zito et al, 2016). Asymmetries have been observed across various tasks and stimulus features.…”

“…Here we set out to test whether these inconsistencies, both between and within studies, could be due to a combination of stimulus differences and processing asymmetries across the visual field. It has long been known that there are anatomic and functional differences between the upper and lower parts of the visual field ( Hansen et al, 2016 ; Skrandies, 1987 ; Zhou et al, 2017 ; Zito et al, 2016 ). Asymmetries have been observed across various tasks and stimulus features.…”

Asymmetries of the visual system and their influence on visual performance and oculomotor dynamics

“…The lower visual hemifield may have stronger connections with the dorsal stream of vision for action whereas the upper visual hemifield is more connected to the ventral stream of vision for perception (Galletti, Fattori, Kutz, & Gamberini, ; Gamberini, Galletti, Bosco, Breveglieri, & Fattori, ; Previc, ; Rossit et al., ). In a recent study, Zhou, Yu, Yu, Wu, and Zhang () proposed that this asymmetry was related to peripersonal and extrapersonal spaces. Accordingly, visually guided actions initiated by the dorsal stream are mainly executed in peripersonal space; which often occurs in the lower visual hemifield.…”

“…Several psychophysical experiments have indeed shown better performance for visually guided actions in the lower visual hemifield than in the upper one (Amenedo, Pazo‐Alvarez, & Cadaveira, ; Genzano, Di Nocera, & Ferlazzo, ; Rubin, Nakayama, & Shapley, ; Thomas & Elias, ). Moreover, discrimination performance in egocentric reference frames has been shown to be enhanced in the lower visual hemifield whereas it was enhanced in the upper visual hemifield when the task was performed within an allocentric reference frame (Levine & McAnany, ; Zhou et al., ).…”

Shorter fixation durations for up-directed saccades during saccadic exploration: A meta-analysis

“…An object positioned above or below the current eye fixation is respectively in the current upper or lower visual field. It is well established that temporal processing along the vertical meridian of the visual field is asymmetric (Previc, 1990;Skrandies, 1987;Woodworth, 1938;Y. Zhou, Yu, Xuefei, Wu, & Zhang, 2017).…”