Juan Chen

Action planning has been traditionally viewed through the lens of motor command specification. However, converging evidence indicates planning also modulates early cortical sensory systems. While previous studies mainly focused on the modulation to a single target object, it remains unclear how action planning modulates the spatial interaction between target and flankers in a cluttered scene. Here we directly tested this using EEG with frequency tagging to measure visual surround suppression—a key cortical mechanism for object segregation—while participants (22 females, 14 males) planned to grasp a target among flankers. We hypothesized that surround suppression, essential for distinguishing the target from distractors, would be enhanced when planning to grasp the target compared with planning a nontarget-directed action where segregation is less critical. Further, based on evidence suggesting that surround suppression when “executing” a grasping movement is greater for dominant than nondominant hand, we predict that this specificity should likewise exist during “planning”. Confirming our predictions, EEG results demonstrated that planning a grasp significantly amplified surround suppression relative to planning a simple key release. This enhancement was additively modulated by target relevance and hand dominance, being strongest when planning a dominant-hand grasp. Crucially, a control task (planning a perceptual judgment) elicited no such suppression, supporting the action specificity of this sensory tuning. These results provide neural evidence at the level of visual mechanisms that action preparation actively and selectively refines early sensory processing for efficient goal-directed action.

A growing body of research suggests that sports training enhances high-level cognitive functions, including sensory perception, sensorimotor skills, executive control, memory, attention, and processing speed. However, it is still unclear the extent to which the improvement in sensorimotor skills can be generalized to new contexts, especially in children. We examined the effects of tennis training on walking distance using the blind walking task (viewing targets and then walking blindfolded). Unlike reaching a ball while looking at it in lit environments and familiar space during tennis training, our blind walking task required looking at an object at unfamiliar distances, and then walking to its location with eyes blindfolded - a novel context in stark contrast with the tennis training environment. Performance was measured through signed errors, absolute errors, and the correlation between walked distance and target distance. Tennis-trained children (age: 9.34 ± 1.82 years old) showed lower absolute errors and stronger correlations than controls, indicating reduced noise and enhanced sensorimotor consistency. Tennis-trained adults (age: 22.70 ± 3.75 years old) demonstrated improved correlations without error reduction, suggesting training primarily enhanced sensorimotor alignment. As blind walking requires integrating visual-proprioceptive information to form internal sensorimotor representations, our findings suggest that tennis training improves distance-guided action, probably by modifying the fundamental sensorimotor model, so that it can transfer to completely different contexts, which indicates that sports training can be a viable cognitive training tool.

Our perception of objects depends on non-oculomotor depth cues, such as pictorial distance cues and binocular disparity, and oculomotor depth cues, such as vergence and accommodation. Although vergence eye movements are always involved in perceiving real distance, previous studies have mainly focused on the effect of oculomotor state via “proprioception” on distance and size perception. It remains unclear whether the oculomotor command of vergence eye movement would also influence visual processing. To address this question, we placed a light at 28.5 cm and a screen for stimulus presentation at 57 cm from the participants. In the NoDivergence condition, participants were asked to maintain fixation on the light regardless of stimulus presentation throughout the trial. In the WithDivergence condition, participants were instructed to initially maintain fixation on the near light and then turn their two eyes outward to look at the stimulus on the far screen. The stimulus was presented for 100 msec, entirely within the preparation stage of the divergence eye movement. We found that participants perceived the stimulus as larger but were less sensitive to stimulus sizes in the WithDivergence condition than in the NoDivergence condition. The earliest visual evoked component C1 (peak latency 80 msec), which varied with stimulus size in the NoDivergence condition, showed similar amplitudes for larger and smaller stimuli in the WithDivergence condition. These results show that vergence eye movement planning affects the earliest visual processing and size perception, and demonstrate an example of the effect of motor command on sensory processing.

In the real world, every object has its canonical distance from observers. For example, airplanes are usually far away from us, whereas eyeglasses are close to us. Do we have an internal representation of the canonical real-world distance of objects in our cognitive system? If we do, does the canonical distance influence the perceived size of an object? Here, we conducted two experiments to address these questions. In Experiment 1, we first asked participants to rate the canonical distance of objects. Participants gave consistent ratings to each object. Then, pairs of object images were presented one by one in a trial, and participants were asked to rate the distance of the second object (i.e., a priming paradigm). We found that the rating of the perceived distance of the target object was modulated by the canonical real-world distance of the prime. In Experiment 2, participants were asked to judge the perceived size of canonically near or far objects that were presented at the converging end (i.e., far location) or the opening end (i.e., near location) of a background image with converging lines. We found that regardless of the presentation location, participants perceived the canonically near object as smaller than the canonically far object even though their retinal and real-world sizes were matched. In all, our results suggest that we have an internal representation of the canonical real-world distance of objects, which affects the perceived distance of subsequent objects and the perceived size of the objects themselves.

Object recognition relies on a multitude of factors, including size, orientation, and so on. Mirrored orientation, particularly due to children's mirror confusion in reading, holds special significance among various object orientations. Brain imaging studies suggest that the visual ventral and dorsal streams exhibit distinct orientation sensitivity across diverse object categories. Yet, it remains unclear whether mirror orientation sensitivity also varies among these categories during development at the behavioral level. Here, we explored the mirror sensitivity of children and adults across five distinct categories, which encompass tools that activate both the visual ventral stream for function information and the dorsal stream for manipulation information, and animals and faces that mainly activate the ventral stream. Two types of symbols, letters and Chinese characters, were also included. Mirror sensitivity was assessed through mirror costs—that is, the additional reaction time or error rate in the mirrored versus the same orientation condition when judging the identity of object pairs. The mirror costs in reaction times and error rates consistently revealed that children exhibited null mirror costs for tools, and the mirror costs for tools in adults were minimal, if any, and were smaller than those for letters and characters. The mirror costs reflected in absolute reaction time and error rate were similar across adults and children, but when the overall difference in reaction times was considered, adults showed a larger mirror cost than children. Overall, our investigation unveils categorical distinctions and development in mirror sensitivity of object recognition across the ventral and dorsal streams.