Vision Research最新文献

Research has demonstrated that humans possess the remarkable ability to swiftly extract ensemble statistics, specifically the average identity, from sets of stimuli, such as facial crowds. This phenomenon is known as ensemble perception. Although previous studies have investigated how physiognomic features like gender and race influence face ensemble perception, the impact of face age on face ensemble coding performance remains a relatively unexplored area. Here, we demonstrated ensemble coding of multiple faces in terms of an average face was impacted by face age. In both Experiment 1 and 2, adult participants viewed sets of four faces that were of either own-age or other-age and then judged whether the subsequently presented probe face was present or not in the preceding set. The other-age faces were manipulated as older faces in Experiment 1 and baby faces in Experiment 2. The results suggested participants incorrectly endorsed a morphed set average to be the member of the set, pointing to face ensemble coding ability. Furthermore, the results of Experiment 1 revealed adult participants displayed an own-age superiority when other-age faces were manipulated as older faces, however, the results of Experiment 2 found when other-age faces were manipulated as baby faces, participants displayed stronger visual averaging tendency towards other-age faces rather own-age faces, showing a babyface effect. Together, the present research provided initial evidence that face ensemble coding performance was modulated by face age.

Elevated intraocular pressure (IOP) is a significant risk factor for glaucoma, causing structural and functional damage to the eye. Increased IOP compromises the metabolic and structural integrity of retinal ganglion cell (RGC) axons, leading to progressive degeneration and influencing the ocular immune response. This study investigated early cellular and molecular changes in the retina and optic nerve (ON) following ocular hypertension (OHT). A pigmented rat model was used, with OHT induced through low-temperature cauterization of the limbal vascular plexus. To assess the effects at early time points after OHT, transmission electron microscopy (TEM) was employed to analyze ultrastructural changes in the retina and ON, while immunofluorescence was used to evaluate cellular responses. Flow cytometry was used to examine alterations in immune-cell populations. Within 24 h post-OHT, ultrastructural changes were detected in the cytoplasm of RGCs, indicating early cellular alterations undetectable by conventional microscopy. These ultrastructural modifications progressed further at 48 and 72 h, despite the absence of overt RGC loss or disruptions in retinal layer integrity. Changes in the axons and nodes of Ranvier were evident within the first 24 h after ocular hypertension, becoming more pronounced by 72 h. These findings offer novel insights into the early pathogenesis of glaucoma, highlighting critical early impacts that could guide the development of new therapeutic strategies to prevent irreversible RGC loss.

Individuals with mild traumatic brain injury (mTBI) exhibit significant accommodative abnormalities. Accommodation microfluctuation (MFs) plays an important role in the accommodation steady-state control. This study was set to investigate the characteristics of the MFs in mTBI subjects and whether chromatic filter (CF) or neutral density filter (ND) would impact these parameters. 54 healthy and 30 mTBI young adults participated. Tonic accommodation (TA) was recorded in complete darkness after dark adaptation. The steady-state accommodation response (AR) for various stimulus distances was recorded at baseline (no filter; NF), with CF and ND. The low and high frequency component (LFC and HFC respectively) of MFs was analyzed. Subjects with mTBI exhibited significantly lower MFs, especially at higher stimulus levels. There was a strong negative correlation between the accommodation error (AE) and the LFC. Increased lag of accommodation (AE > 0 D) was associated with lower LFC and vice versa. Both filter conditions exerted a minimum impact on the MFs overall. A strong positive correlation between MFs and TA was revealed for both groups. Our study showed that mTBI significantly impaired the MFs of accommodation. The observed lower MFs power in mTBI appears to be subsequent to the higher lag of accommodation, suggesting an underlying deficit in the accommodative motor controller to generate sufficient response. The strong correlation between TA and MFs, as well as the lack of effect from different filters, further supports the theory that sensory blur detection does not play a significant role in MFs of accommodation.

Visual perceptual learning often requires a substantial number of trials to observe significant learning effects. Previously Amar-Halpert et al. (2017) have shown that brief reactivation (5 trials/day) is sufficient to improve the performance of the texture discrimination task (TDT), yielding comparable improvements to those achieved through full practice (252 trials/day). The finding is important since it would refine our understanding of learning mechanisms and applications. In the current study, we attempted to replicate these experiments using a larger number of observers and an improved experimental design. Using between-group comparison, we did find significant improvements in the reactivation group and the full-practice group as Amar-Halpert et al. (2017) showed. However, these improvements were comparable to those of the no-reactivation group with no exposure to the TDT task over the same period. Importantly, our within-group comparison showed that both the reactivation and no-reactivation groups exhibited additional significant improvements after further practicing the TDT task for an additional three days, demonstrating that the full-practice effect was significantly superior to the effects of brief memory reactivation or simple test-retest. Besides, when refining the constant stimuli method with fewer stimulus levels and more trials per level, we still observed comparable improvements brought by the reactivation and no-reactivation groups. Therefore, our results suggested that brief memory reactivation may not significantly contribute to the improvement of perceptual learning, and traditional perceptual training could still be a necessary and effective approach for substantial improvements.

Serial dependence (SD) is said to occur when the judgment of a current stimulus is drawn toward a no longer relevant stimulus from the recent past. Working memory (WM) contributes to the ability to discriminate between irrelevant and relevant sensory impressions. How WM contributes to SD in facial identity remains to be fully understood. In the present study, we used a WM task with varying load interleaved with a facial matching task to investigate the relations between SD in facial identity and WM. EEG was recorded to capture perceptual face processing and WM maintenance. Overall, statistically significant SD effects were obtained only at high WM load. In addition, individual differences in WM capacity predicted SD. Participants with low WM capacity showed significant SD effects regardless of changes in WM load, while participants with high WM capacity showed significant SD only at high WM load. EEG results showed significant differences in perceptual and WM processing for participants with high WM capacity, while no significant differences were obtained for participants with low WM capacity. Neural correlates of WM maintenance, and perceptual processing of a previous face were directly related to SD. The results suggest that WM capacity contributes to SD in facial identity, in terms of selective suppression of task-irrelevant and selective maintenance of task-relevant information.

The present study investigated the mechanisms of visual stability using naturalistic scene images. In two experiments, we asked whether the visual system relies on spatial location of the saccade target, as previously found with simple dot stimuli, or relational positions of the objects in the scene during visual stability decisions. Using a modified version of the saccadic suppression of displacement task, we manipulated the information that is displaced in the scene as well as visual stability using intrasaccadic target blanking paradigm. There were four displacement conditions: saccade target, saccade source (Experiment 2 only), whole scene, and background. We also included a no-displacement control condition where everything remained stationary. Participants reported whether they detected any movement. The results showed that spatial displacements that occur in the saccade target object were more easily detected than any other displacements in the scene. Further, disrupting visual stability with blanking only improved displacement detection for the saccade target and saccade source objects, suggesting that saccade target and saccade source objects are both consulted in the establishment of visual stability, most likely due to both receiving selective attention before saccade execution. The present study is the first to show that the visual system uses similar visual stability mechanisms for simple dot stimuli and more naturalistic stimuli.

Prior research has established that actions, such as eye movements, influence time perception. However, the relationship between pre-saccadic attention, which is often associated with eye movement, and subjective time perception is not explored. Our study examines the impact of pre-saccadic attention on the subjective experience of time during eye movements, particularly focusing on its influence on subjective time perception at the saccade target. Participants were presented with two clocks featuring spinning hands, positioned at distinct locations corresponding to fixation and the saccade target. They were required to report the perceived time of these clocks across the eye movements, enabling us to measure and compare both the perceived and actual timing at these specific clock locations. In Experiment 1, we observed that participants tended to report the timing of their eyes' arrival at the target location as occurring slightly ahead of the actual time. In contrast, in Experiment 2, when participants divert their attention to the fixation clock prior to the imperative saccade, this perceptual bias diminishes. These results indicate that subjective time perception is strongly impacted by attentional conditions across the two experiments. Together, these findings offer further evidence for the notion that stable time perception during eye movements is not solely an inherent property of the eye movement system but also encompasses other cognitive mechanisms, such as attention. STATEMENT OF RELEVANCE: While we often remain unaware of the frequent saccades (rapid eye movements) we make, they have a profound impact on our perception of the world and the flow of time. Nevertheless, the connection between pre-saccadic attention, often associated with eye movements, and our subjective perception of time remains largely unexplored. In our research, we investigated the relationship between attention and our subjective experience of time. Our findings revealed the crucial role of attention, serving as a bridge between the physical movements of our eyes and our internal sense of temporal continuity. In essence, although previous studies have demonstrated the impact of eye movements on time perception, our current study emphasizes the critical influence of attention during the preparatory phase of saccades on the subjective experience of time during eye movements.

The traditional understanding of brain function has predominantly focused on chemical and electrical processes. However, new research in fruit fly (Drosophila) binocular vision reveals ultrafast photomechanical photoreceptor movements significantly enhance information processing, thereby impacting a fly's perception of its environment and behaviour. The coding advantages resulting from these mechanical processes suggest that similar physical motion-based coding strategies may affect neural communication ubiquitously. The theory of neural morphodynamics proposes that rapid biomechanical movements and microstructural changes at the level of neurons and synapses enhance the speed and efficiency of sensory information processing, intrinsic thoughts, and actions by regulating neural information in a phasic manner. We propose that morphodynamic information processing evolved to drive predictive coding, synchronising cognitive processes across neural networks to match the behavioural demands at hand effectively.

The study of scene perception is crucial to the understanding of how one interprets and interacts with their environment, and how the environment impacts various cognitive functions. The literature so far has mainly focused on the impact of low-level and categorical properties of scenes and how they are represented in the scene-selective regions in the brain, PPA, RSC, and OPA. However, higher-level scene perception and the impact of behavioral goals is a developing research area. Moreover, the selection of the stimuli has not been systematic and mainly focused on outdoor environments. In this fMRI experiment, we adopted multiple behavioral tasks, selected real-life indoor stimuli with a systematic categorization approach, and used various multivariate analysis techniques to explain the neural modulation of scene perception in the scene-selective regions of the human brain. Participants (N = 21) performed categorization and approach-avoidance tasks during fMRI scans while they were viewing scenes from built environment categories based on different affordances ((i)access and (ii)circulation elements, (iii)restrooms and (iv)eating/seating areas). ROI-based classification analysis revealed that the OPA was significantly successful in decoding scene category regardless of the task, and that the task condition affected category decoding performances of all the scene-selective regions. Model-based representational similarity analysis (RSA) revealed that the activity patterns in scene-selective regions are best explained by task. These results contribute to the literature by extending the task and stimulus content of scene perception research, and uncovering the impact of behavioral goals on the scene-selective regions of the brain.

Visual adaptation to thin or large bodies was found to shift the subjective body normality towards the adapting body shape. Here we investigated the persistency of such adaptation effect by tracking the timecourse of decay of short-term body size adaptation in young healthy Chinese women. Participants adapted to contracted or expanded body images of unfamiliar female volunteers with a top-up paradigm. Their subjective point of normal body size (PNS) was measured before, immediately after and 10/20/30 min after adaptation. The results showed that about 12 min of adaptation to contracted or expanded body stimuli could shift participants' estimations of body normality towards the adapting body shape, with the effect sustaining for more than 30 min after the end of adaptation. In addition, by fitting the timecourse of decay of adaptation with the exponential, power or logarithmic functions, we found that the recovery of body size adaptation effect could be best described with the logarithmic models. These findings indicated that short-term exposure to distorted body shapes of other people could lead to a lingering bias on body size estimation.