Looking at the Ebbinghaus illusion: differences in neurocomputational requirements, not gaze-mediated attention, explain a classic perception-action dissociation

The development of visual attention to the Ebbinghaus illusion across two cultures

Selective attention typically becomes more refined with age, improving significantly from early to middle childhood. However, under certain conditions, such as the Ebbinghaus illusion task, younger children may display more focused selective attention than older children and adults. Cross-cultural differences have also been documented, with North American participants tending to focus selectively on central targets, while East Asian participants attending holistically and showing greater susceptibility to the illusion. Despite these findings, the physiological mechanisms underlying these age-related and cultural differences remain unclear. Specifically, does susceptibility to the illusion align with what we attend to? The present study investigated age-related and culture-related changes in susceptibility to the Ebbinghaus illusion among 3- to 8-year-old children in Japan and the U.S. using eye-tracking methods. The results revealed that older children and Japanese children were more susceptible to the Ebbinghaus illusion than younger children. Importantly, behavioral susceptibility was linked to gaze fixation patterns. In both cultures, the proportion of total fixation time on the correct target area, including target and distractor circles, rather than selective attention to targets alone, predicted susceptibility to the Ebbinghaus illusion. These findings highlight the role of gaze fixation in shaping perceptual experiences across developmental and cultural contexts.

Simple actions modulate context-dependent visual size perception at late processing stages

A simple button press towards a prime stimulus enhances subsequent visual search for objects that match the prime. The present study investigated whether this action effect is a general phenomenon across different task domains, and the underlying neural mechanisms. The action effect was measured in an unspeeded size-matching task, with the presentation of the central target and the surrounding inducers of the Ebbinghaus illusion together to one eye or separately to each eye, and when repetitive TMS was applied over right primary motor cortex (M1). The results showed that a prior key-press significantly reduced the illusion effect compared to passive viewing. Notably, the action effect persisted with dichoptic presentation of the Ebbinghaus configuration, but disappeared with the right M1 disruption. These results suggest that action guides visual perception to influence human behavior, which mainly affects the late visual processing stage and probably relies on feedback projections from the motor cortex.

Exploring perceptual grouping by proximity principle in multistable dot lattices: Dissociation between vision-for-perception and vision-for-action

Perceptual grouping, a fundamental mechanism in our visual system, significantly influences our interpretation of and interaction with the surrounding world. This study explores the impact of the proximity principle from the perspective of the Two Visual Systems (TVS) model. The TVS model argues that the visual system comprises two distinct streams: the ventral stream, which forms the neural basis for "vision-for-perception," and the dorsal stream, which underlies "vision-for-action." We designed a perceptual grouping task using dot lattices as well as a line-orientation discrimination task. Data were collected using vocal and mouse methods for the vision-for-perception mode, and joystick and pen-paper methods for the vision-for-action mode. Each method, except for vocal, included separate blocks for right and left hands. The proximity data were fitted using exponential and power models. Linear mixed-effects models were used for the statistical analyses. The results revealed similar line-orientation discrimination accuracy across all conditions. The exponential model emerged as the best fit, demonstrating adherence to the Pure Distance Law in both perceptual modes. Sensitivity to the proximity principle was higher in the vision-for-action mode compared to the vision-for-perception. In terms of orientation biases, a strong preference for vertical orientation was observed in the vision-for-perception mode, whereas a noticeable preference toward either of the oblique orientations was detected in the vision-for-action mode. Analysis of free-drawn lines demonstrated an affordance bias in the vision-for-action mode. This suggests a remarkable tendency to perceive organizations within specific orientations that offer more affordances due to the interaction between the body postures and tools.

Perceived image size modulates visual memory

Previous studies have demonstrated that visual memory is improved when stimuli are processed by larger cortical regions. For example, a physically large stimulus that recruits larger areas of the retinotopic cortex is better remembered. However, the spatial extent of neural responses in the visual cortex is not only modulated by the retinal size of a stimulus, but also by the perceived size of the stimulus. In this online study, we modulated the perceived size of the visual stimuli using the Ebbinghaus illusion and asked participants to remember the stimuli. The results showed that perceptually larger images were remembered better than perceptually smaller but physically same-sized images. Our finding supports the idea that visual memory is modulated by top-down feedback from higher visual regions to the early visual cortex.

New Approaches to 3D Vision

New approaches to 3D vision are enabling new advances in artificial intelligence and autonomous vehicles, a better understanding of how animals navigate the 3D world, and new insights into human perception in virtual and augmented reality. Whilst traditional approaches to 3D vision in computer vision (SLAM: simultaneous localization and mapping), animal navigation (cognitive maps), and human vision (optimal cue integration) start from the assumption that the aim of 3D vision is to provide an accurate 3D model of the world, the new approaches to 3D vision explored in this issue challenge this assumption. Instead, they investigate the possibility that computer vision, animal navigation, and human vision can rely on partial or distorted models or no model at all. This issue also highlights the implications for artificial intelligence, autonomous vehicles, human perception in virtual and augmented reality, and the treatment of visual disorders, all of which are explored by individual articles. This article is part of a discussion meeting issue 'New approaches to 3D vision'.