​Karakashevska and colleagues (2025) examined the extraretinal representation of visual symmetry presented in a virtual reality environment. Previous research has demonstrated that individuals can detect symmetry when the symmetry is represented on a perspective plane, slanted away from the viewer. In electroencephalography (EEG), perceived symmetry is marked by an Event Related Potential (ERP) called a Sustained Posterior Negativity (SPN). When symmetry is presented on a perspective plane in comparison to front-on (frontoparallel), the SPN is reduced, termed the perspective cost. Here, Karakashevska et al. (2025) determined if presenting symmetry on a perspective plane in a virtual reality (VR) environment reduced the perspective cost with the addition of 3D depth cues. Specifically, participants were requested to detect symmetry or luminance of a stimulus presented in a VR environment whilst wearing an EEG.

 

The authors found no perspective cost during the regularity task when symmetry was presented on a frontoparallel plane versus symmetry on a perspective plane. When participants were performing the luminance task, the authors found no conclusive evidence for the presence or absence of perspective cost. Together these data suggest that when immersed in a virtual reality (VR) environment, critical depth cues are available to overcome perspective cost in the perception of symmetry. 

 

The Stage 2 manuscript was evaluated by two expert reviewers. One of our reviewers reviewed the Stage 1 manuscript, and one reviewer was new. The reviewers agreed that the authors had adhered to their registered Stage 1 manuscript and were convinced by the interpretation of the results. The recommender has determined that the Stage 2 criteria was met and has awarded a positive recommendation. ​

 

URL to the preregistered Stage 1 protocol: https://osf.io/7pnxu
 
Level of bias control achieved: Level 6. No part of the data or evidence that was used to answer the research question was generated until after IPA. 

List of eligible PCI RR-friendly journals:

 

• Advances in Cognitive Psychology
• Brain and Neuroscience Advances
• Cortex
• Imaging Neuroscience
• NeuroImage: Reports
• Peer Community Journal
• PeerJ
• Psychology of Consciousness: Theory, Research, and Practice
• Royal Society Open Science
• Studia Psychologica

 

 

Karakashevska, E., Batterley, M/, Yuxin, Y., & Makin, A. D. J. (2025). They look virtually the same: extraretinal representation of symmetry in virtual reality [Stage 2]. Acceptance of Version 2 by Peer Community in Registered Reports. https://doi.org/10.31234/osf.io/sfyg6_v2

 

Visual symmetry is critical to our interaction with our environment so that when detected, symmetry automatically produces a neural marker in the form of an Event Related Potential (ERP) called Sustained Posterior Negativity (SPN). However, when symmetry is presented to the visual system slanted away from the viewer, there is a reduction in SPN, termed a perspective cost. 

 

Considering ​objects are rarely presented front-on (or frontoparallel) in our natural environment, Karakashevska et al., (2023) plan to examine the extent of the perspective cost with the addition of visual cues to facilitate extraretinal representation of the visual symmetry. The authors will record electroencephalography (EEG) from 120 participants while they perform a luminance task on symmetrical and asymmetrical stimuli. The authors hypothesize perspective cost will be reduced by three perspective cues: 1) monocular viewing, when cue conflict caused by binocular viewing is eliminated, 2) a static frame surrounding the symmetrical stimulus, adding a depth cue, and 3) a moving frame, assisting 3D perception prior to the symmetry onset. If the SPN is equivalent during frontoparallel and slanted presentation in a cue condition, the authors will conclude extraretinal representation can be automatic when sufficient visual cues are available. The proposed experiment is powered to detect a relatively small difference between perspective cue conditions. This will solidify fundamental research on visual symmetry processing and will further our understanding of object perception and recognition. 

 

The Stage 1 manuscript was evaluated over three rounds by four expert reviewers. Following in-depth review and responses from the authors, the recommenders have determined that Stage 1 criteria was met and have awarded in-principle acceptance (IPA). 

URL to the preregistered Stage 1 protocol: https://osf.io/yzsq5
 
Level of bias control achieved: Level 6. No part of the data or evidence that will be used to answer the research question yet exists and no part will be generated until after IPA.
 
List of eligible PCI-RR-friendly journals:
 

• Advances in Cognitive Psychology
• Brain and Neuroscience Advances
• Cortex
• F1000Research
• Imaging Neuroscience
• In&Vertebrates
• NeuroImage: Reports
• Peer Community Journal
• PeerJ
• Royal Society Open Science
• Studia Psychologica
• Swiss Psychology Open

 
References
 
1. Karakashevska, E., Bertamini, M. & Makin, A. D. J. (2023). Putting things into perspective: Which visual cues facilitate automatic extraretinal symmetry representation? [Stage 1 Registered Report]. In principle acceptance of Version 4 by Peer Community in Registered Reports. https://osf.io/yzsq5