Visual Behavior Research Articles

A non-conducting role of the Cav1.4 Ca2+ channel drives homeostatic plasticity at the cone photoreceptor synapse

In congenital stationary night blindness, type 2 (CSNB2)—a disorder involving the Cav1.4 (L-type) Ca2+ channel—visual impairment is mild considering that Cav1.4 mediates synaptic release from rod and cone photoreceptors. Here, we addressed this conundrum using a Cav1.4 knockout (KO) mouse and a knock-in (G369i KI) mouse expressing a non-conducting Cav1.4. Surprisingly, Cav3 (T-type) Ca2+ currents were detected in cones of G369i KI mice and Cav1.4 KO mice but not in cones of wild-type mouse, ground squirrels, and macaque retina. Whereas Cav1.4 KO mice are blind, G369i KI mice exhibit normal photopic (i.e. cone-mediated) visual behavior. Cone synapses, which fail to form in Cav1.4 KO mice, are present, albeit enlarged, and with some errors in postsynaptic wiring in G369i KI mice. While Cav1.4 KO mice lack evidence of cone synaptic responses, electrophysiological recordings in G369i KI mice revealed nominal transmission from cones to horizontal cells and bipolar cells. In CSNB2, we propose that Cav3 channels maintain cone synaptic output provided that the nonconducting role of Cav1.4 in cone synaptogenesis remains intact. Our findings reveal an unexpected form of homeostatic plasticity that relies on a non-canonical role of an ion channel.

A non-conducting role of the Cav1.4 Ca2+ channel drives homeostatic plasticity at the cone photoreceptor synapse.

In congenital stationary night blindness, type 2 (CSNB2)-a disorder involving the Cav1.4 (L-type) Ca2+ channel-visual impairment is mild considering that Cav1.4 mediates synaptic release from rod and cone photoreceptors. Here, we addressed this conundrum using a Cav1.4 knockout (KO) mouse and a knock-in (G369i KI) mouse expressing a non-conducting Cav1.4. Surprisingly, Cav3 (T-type) Ca2+ currents were detected in cones of G369i KI mice and Cav1.4 KO mice but not in cones of wild-type mouse, ground squirrels, and macaque retina. Whereas Cav1.4 KO mice are blind, G369i KI mice exhibit normal photopic (i.e. cone-mediated) visual behavior. Cone synapses, which fail to form in Cav1.4 KO mice, are present, albeit enlarged, and with some errors in postsynaptic wiring in G369i KI mice. While Cav1.4 KO mice lack evidence of cone synaptic responses, electrophysiological recordings in G369i KI mice revealed nominal transmission from cones to horizontal cells and bipolar cells. In CSNB2, we propose that Cav3 channels maintain cone synaptic output provided that the nonconducting role of Cav1.4 in cone synaptogenesis remains intact. Our findings reveal an unexpected form of homeostatic plasticity that relies on a non-canonical role of an ion channel.

"Mirror, mirror in the call": Exploring the Ambivalent Nature of the Self-view in Video Meeting Systems with Self-Reported & Eye-Tracking Data

Video meeting systems offer great potential for work and life, but they can also have negative effects. One reason is the presence of technical stimuli that do not exist in the physical world. A prominent example is the self-view feature, a mirrored image of oneself shown during the video meeting. The self-view feature comes with a trade-off between the advantage of enhancing control and the disadvantage of increasing cognitive load of its users. So far, research is scarce when it comes to understanding this ambivalent nature and studies mostly relied on self-reported data without considering the actual interaction with the self-view. To address this gap, we conducted an experimental study with 57 participants and two design variants (with/without self-view), analyzed user perceptions through surveys and interviews, and explored gaze patterns using eye-tracking technology. Results reveal varying perceptions of cognitive load and control among self-view users and between the design variants, highlighting its ambivalent nature. We see differences in how participants interact with the self-view. In a cluster analysis, we identify three user groups (Benefiting Users, Cognitively Challenged Users, Control Losing Users). These groups also show differences in visual behavior, especially median fixation duration, and user characteristics. Based on our findings, we outline design recommendations for more flexible and intelligent design solutions by considering user groups and their individual differences.

Wide-angle simulated artificial vision enhances spatial navigation and object interaction in a naturalistic environment

Objective. Vision restoration approaches, such as prosthetics and optogenetics, provide visual perception to blind individuals in clinical settings. Yet their effectiveness in daily life remains a challenge. Stereotyped quantitative tests used in clinical trials often fail to translate into practical, everyday applications. On the one hand, assessing real-life benefits during clinical trials is complicated by environmental complexity, reproducibility issues, and safety concerns. On the other hand, predicting behavioral benefits of restorative therapies in naturalistic environments may be a crucial step before starting clinical trials to minimize patient discomfort and unmet expectations.Approach. To address this, we leverage advancements in virtual reality technology to conduct a fully immersive and ecologically valid task within a physical artificial street environment. As a case study, we assess the impact of the visual field size in simulated artificial vision for common outdoor tasks.Main results. We show that a wide visual angle (45°) enhances participants' ability to navigate and solve tasks more effectively, safely, and efficiently. Moreover, it promotes their learning and generalization capability. Concurrently, it changes the visual exploration behavior and facilitates a more accurate mental representation of the environment. Further increasing the visual angle beyond this value does not yield significant additional improvements in most metrics.Significance. We present a methodology combining augmented reality with a naturalistic environment, enabling participants to perceive the world as patients with retinal implants would and to interact physically with it. Combining augmented reality in naturalistic environments is a valuable framework for low vision and vision restoration research.

Comparison and AI-based prediction of graph comprehension skills based on the visual strategies of first-year physics and medicine students

Graphical representations of data are common in many disciplines. Previous research has found that physics students appear to have better graph comprehension skills than students from social science disciplines, regardless of the task context. However, the graph comprehension skills of physics students have not yet been compared with (veterinary) medicine students, both of which are disciplines that require multiple science, technology, engineering, and mathematics (STEM) courses. This study extends previous research on this subject by exploring whether physics majors possess superior graph comprehension skills due to their study discipline. Here, participants solved 24 graph comprehension tasks across various subjects, including mathematics, physics, and medicine; these tests were conducted at the beginning and end of their first semester. Graph comprehension gain was calculated based on the percentage of correct and incorrect answers in the pretest and the post-test. In addition to these comparisons, we replicated previous research that successfully distinguished correct and incorrect solvers based on their visual behavior by using a novel machine-learning method tailored to small datasets. Through this replication of statistical analyses, we aim to ensure the reliability of adaptive learning systems in the future, regardless of data size, using the same machine-learning method. Physics and medical students were found to exhibit relatively similar graph comprehension gain; this is in contrast to previous research comparing physics and non-STEM students. Our results also revealed that both physics and medical students use similar visual strategies to solve these tasks. However, correct and incorrect solvers could be distinguished via machine-learning methods regardless of their discipline. Our research suggests that visual behavior is a good predictor of graph comprehension skills. Published by the American Physical Society 2024

Implications of Retrograde Behaviours on Visual and Cycling Behaviour of Normal Cyclists

In China and other developing countries, some bicycle riders exhibit retrograde behaviour, which affects the riding safety of normal cyclists. The effect of retrograde behaviour on visual search and cycling behaviours of normal cyclists is investigated and quantified in this study. First, cyclists are instructed to wear an SMI iView ETG head-mounted mobile eye tracker and a mobile phone equipped with a Global Positioning System real-time location monitoring function to cycle on a road to obtain the times of fixation, saccade and blink, as well as the pupil diameter, gaze position and velocity in normal and retrograde conditions. Subsequently, the effect of retrograde behaviour on the attention of normal cyclists is analysed using three indexes: proportion of fixation time, coefficient of variation of pupil diameter and area of interest. Then, the effect of cycling behaviour is analysed using three indexes: the cycling trajectory, the velocity at three stages and the coefficient of variation of velocity. Finally, polynomial regression analysis is performed to analyse the visual and cycling behaviour impact indexes under the retrograde condition. The results show that retrograde behaviour significantly affects the vision and cycling behaviour of normal cyclists and that the two indexes are positively correlated.

Gaze and hand behaviors during haptic abilities testing-An update to multimedia learning theory.

The Cognitive Theory of Multimedia Learning (CTML) suggests humans learn through visual and auditory sensory channels. Haptics represent a third channel within CTML and a missing component for experiential learning. The objective was to measure visual and haptic behaviors during spatial tasks. The haptic abilities test (HAT) quantifies results in several realms, accuracy, time, and strategy. The HAT was completed under three sensory conditions using sight (S), haptics (H), and sight with haptics (SH). Subjects (n = 22, 13 females (F), 20-28 years) completed the MRT (10.6 ± 5.0, mean ± SD) and were classified as high or low spatial abilities scores with respect to mean MRT: high spatial abilities (HSA) (n = 12, 6F, MRT = 13.7 ± 3.0), and low spatial ability (LSA) groups (n = 10, 7F, MRT = 5.6 ± 2.0). Video recordings gaze and hand behaviors were compared between HSA and LSA groups across HAT conditions. The HSA group spent less time fixating on mirrored objects, an erroneous answer option, of HAT compared to the LSA group (11.0 ± 4.7 vs. 17.8 ± 7.3 s, p = 0.020) in S conditions. In haptic conditions, HSA utilized a hand-object interaction strategy characterized as palpation, significantly less than the LSA group (23.2 ± 16.0 vs. 43.1 ± 21.5 percent, p = 0.022). Before this study, it was unclear whether haptic sensory inputs appended to the mental schema models of the CTML. These data suggest that if spatial abilities are challenged, LSA persons both benefit and utilize strategies beyond the classic CTML framework by using their hands as a third input channel. This data suggest haptic behaviors offer a third type of sensory memory resulting in improved cognitive performance.

Early visual modulation and selection predict saccadic timing during visual search: An ERP study.

Saccadic eye movements, a critical aspect of real-world visual behavior, are preceded by an initial accumulation of visual information followed by the selection of a single location to move one's eyes. However, it is currently unclear how each of these stages uniquely affects saccadic timing. In this study, participants searched for a contour integration target while EEG was used to measure posterior cortical activity between search display onset and first saccade initiation. The goal was to determine whether saccade timing could be attributed to differences in early ERP amplitudes, with the P1 reflecting the magnitude of early perceptual information accumulation and the N1 reflecting the strength of selection leading to the saccadic decision. EOG was used to measure saccade timing, and trials were divided into fast, middle, and slow bins. The N1 response was smallest in the slow saccade tertile, relative to both the fast and middle tertiles, suggesting weak selection. In contrast, the P1 response was largest for this same slow saccadic tertile relative to the middle saccadic tertile, suggesting vigorous information accumulation. Therefore, delays in saccadic behavior may occur when the visual system is overwhelmed with visual input, thus increasing the time to reach a saccadic decision. These findings reconcile models of eye movement behavior which often prioritize either the impact of information accrual or selection, rather than regarding both as an integrated whole.

I Prefer to Look at an Animal Rather than at a Human: Visual Attention of Neurotypical Children and Children with Autism Spectrum Disorder (ASD) During One-Time First Exposure to an Assistance Dog

Interacting with animals often provides numerous benefits for children with autism spectrum disorder (ASD). One potential explanation for this is that children with ASD exhibit particular visual attention to animals. This study aimed to characterize the visual attention patterns towards humans and animals in children with ASD compared to neurotypical (NT) children during one-time first exposure to an assistance dog. Forty children participated (18 ASD, 22 NT). The interventions were videorecorded. Three categories of visual attention (gaze, glance, and mutual gaze) directed towards assistance dogs and human professionals were coded using ethological methods. Both the children with ASD and the NT children gazed more frequently at the assistance dog than at the professional. However, although infrequently, both groups shared more mutual gazes with the professional than with the assistance dog. Both the NT children and the children with ASD preferred to gaze rather than to glance at, or share mutual gazes with, the assistance dogs. The attention patterns of the NT children towards the professionals were consistent, whereas those of the children with ASD were not. Statistical linear models revealed that a child’s status (ASD/NT) was the only factor influencing the frequency and duration of the visual behaviors observed. These results confirm that individuals with ASD exhibit particularly focused attention towards animals.

Activity-dependent synapse clustering underlies eye-specific competition in the developing retinogeniculate system.

Co-active synaptic connections are often spatially clustered to facilitate local dendritic computations underlying learning, memory, and basic sensory processing. In the mammalian visual system, retinal ganglion cell (RGC) axons converge to form clustered synaptic inputs that enable local signal integration in the dorsal lateral geniculate nucleus (dLGN) of the thalamus. While visual experience promotes retinogeniculate synapse clustering after eye-opening, the earliest events in cluster formation prior to visual experience are unknown. Here, using volumetric super-resolution single-molecule localization microscopy and eye-specific labeling of developing retinogeniculate synapses in mice, we show that synaptic clustering is eye-specific and activity-dependent during retinogeniculate refinement in the first postnatal week. We identified a subset of retinogeniculate synapses with multiple active zones that are surrounded by like-eye synapses and depleted of synapse clustering from the opposite eye. In mutant mice with disrupted spontaneous retinal wave activity, synapses with multiple active zones still form, but do not exhibit the synaptic clustering seen in controls. These results highlight a role for spontaneous retinal activity in regulating eye-specific synaptic clustering in circuits essential for visual perception and behavior.

Can Eye Tracking Help Assess the State of Consciousness in Non-Verbal Brain Injury Patients?

Background/Objectives: Developments in eye-tracking technology are opening up new possibilities for diagnosing patients in a state of minimal consciousness because they can provide information on visual behavior, and the movements of the eyeballs are correlated with the patients' level of consciousness. The purpose of this study was to provide validation of a tool, based on eye tracking by comparing the results obtained with the assessment obtained using the Coma Recovery Scale-Revised (CRS-R). Methods: The mul-ti-center clinical trial was conducted in Poland in 2022-2023. The results of 46 patients who were not able to communicate verbally due to severe brain injury were analyzed in this study. The state of consciousness of patients was assessed using the Minimally Conscious State Detection test (MCSD), installed on an eye tracker and compared to CRS-R. The examinations consisted of performing the MCSD test on patients five times (T1-T5) within 14 days. Collected data were processed based on the FDA and GCP's regulatory requirements. Depending on the nature of the data, the mean and standard deviation, median and lower and upper quartiles, and maximum and minimum values were calculated. Passing-Bablok regression analysis was used to assess the measurement equiva-lence of the methods used. Results: There was no difference between the MCSD and CRS-R in the raw change between T5 and T1 time points, as well as in the total % of points from all time points. The MCSD results from each time point show that at least the first two measurements serve to famil-iarize and adapt the patient to the measurement process, and the third and next measurement should be considered reliable. Conclusions: The results indicated a significant relationship be-tween the scores obtained with MCSD and CRS-R. The results suggest that it seems reasonable to introduce an assessment of the patient's state of consciousness based on eye-tracking technology. The use of modern technology to assess a patient's state of consciousness opens up the opportunity for greater objectivity, as well as a reduction in the workload of qualified personnel.

Advancing remote sensing: a unified deep learning approach with pretrained and custom architectures for high-precision classification

Advancement of remote sensing is vital for accurate land cover mapping and ecological surveillance. This research proposes a cutting-edge deep learning framework that integrates a meticulously designed customary network architecture with the effectiveness of pre-trained models, namely GoogleNet, VGG16, and InceptionV3. Our approach captures the complex features of RGB satellite images throughout various land cover categories using diverse EuroSAT datasets. Our system achieves an impressive 99.40% test accuracy by implementing feature extraction through effective models with a customized deep learning network in an intuitive manner. High class-wise accuracies are observed, ranging from 96.00% to 100.00%, whereas F1-scores, precision, and recall all converge at 99.40%. The aforementioned results demonstrate our approach’s perspective to significantly improve analysis while also confirming its superiority. These results not only confirm the performance of our algorithm but also show that it could be used to redesign satellite visual analysis behavior. These results open the window to further improve and accurate remote sensing systems, giving a helpful viewpoint for researchers as well as professionals.

Emc1 is essential for vision and zebrafish photoreceptor outer segment morphogenesis.

Inherited retinal diseases (IRDs) are a rare group of eye disorders characterized by progressive dysfunction and degeneration of retinal cells. In this study, we characterized the raifteirí (raf) zebrafish, a novel model of inherited blindness, identified through an unbiased ENU mutagenesis screen. A mutation in the largest subunit of the endoplasmic reticulum membrane protein complex, emc1 was subsequently identified as the causative raf mutation. We sought to elucidate the cellular and molecular phenotypes in the emc1-/- knockout model and explore the association of emc1 with retinal degeneration. Visual behavior and retinal electrophysiology assays demonstrated that emc1-/- mutants had severe visual impairments. Retinal histology and morphometric analysis revealed extensive abnormalities, including thinning of the photoreceptor layer, in addition to large gaps surrounding the lens. Notably, photoreceptor outer segments were drastically smaller, outer segment protein expression was altered and hyaloid vasculature development was disrupted. Transcriptomic profiling identified cone and rod-specific phototransduction genes significantly downregulated by loss of emc1. These data shed light on why emc1 is a causative gene in inherited retinal disease and how outer segment morphogenesis is regulated.

X-Tracker: Automated Analysis of Xenopus Tadpole Visual Avoidance Behavior.

Xenopus laevis tadpoles exhibit an avoidance behavior when they encounter a moving visual stimulus. A visual avoidance event occurs when a moving object approaches the eye of a free-swimming animal at an approximately 90-degree angle and the animal turns in response to the encounter. Analysis of this behavior requires tracking both the free-swimming animal and the moving visual stimulus both prior to and after the encounter. Previous automated tracking software does not discriminate the moving animal from the moving stimulus, requiring time-consuming manual analysis. Here we present X-Tracker, an automated behavior tracking code that can detect and discriminate moving visual stimuli and free-swimming animals and score encounters and avoidance events. X-Tracker is as accurate as human analysis without the human time commitment. We also present software improvements to our previous visual stimulus presentation and image capture that optimize videos for automated analysis, and hardware improvements that increase the number of animal-stimulus encounters. X-Tracker is a high throughput, unbiased, and significant time-saving analysis system that will greatly facilitate visual avoidance behavior analysis of Xenopus laevis tadpoles, and potentially other free-swimming organisms. The tool is available at https://github.com/ClineLab/Tadpole-Behavior-Automation.

Driving performance and ocular activity following acute administration of 10 mg methylphenidate: A randomised, double-blind, placebo-controlled study.

Methylphenidate is a routinely prescribed treatment for attention-deficit/hyperactivity disorder with misuse potential owing to its perceived performance-enhancing and euphoric properties. Although clinically effective, there is limited understanding of how methylphenidate affects safety-sensitive tasks such as driving when used by healthy individuals. Explore the acute effects of 10 mg methylphenidate on driving performance and gaze behaviour. Twenty-five fully licensed, healthy adults (mean age = 33.5 ± 7.8 years, 64% male) took part in two 40-min simulated highway drives with simultaneous eye movements monitored using a proprietary automotive-grade driver monitoring system (Seeing Machines). Driving performance was assessed using the standard deviation of lateral position, standard deviation of speed and steering variability. Visual scanning efficiency was determined using ocular metrics, such as fixation duration and rate, gaze transition entropy, and stationary gaze entropy, were assessed to determine visual scanning efficiency. Methylphenidate significantly improved driving performance by reducing lane weaving and speed variation, particularly in the latter half of the drive. Although a significant reduction in fixation duration was observed, all other ocular metrics remained unchanged. Methylphenidate mitigates performance decrements typically associated with prolonged and monotonous driving. The absence of pronounced oculomotor effects suggests that a single 10 mg dose of methylphenidate has no deleterious impact on visual scanning behaviour during driving tasks with low-to-moderate cognitive demand. Future research should investigate the effects of methylphenidate under various dosing and driving conditions to better understand its impact. ACTRN12620000499987.

The visual experience dataset: Over 200 recorded hours of integrated eye movement, odometry, and egocentric video.

We introduce the Visual Experience Dataset (VEDB), a compilation of more than 240hours of egocentric video combined with gaze- and head-tracking data that offer an unprecedented view of the visual world as experienced by human observers. The dataset consists of 717 sessions, recorded by 56 observers ranging from 7 to 46 years of age. This article outlines the data collection, processing, and labeling protocols undertaken to ensure a representative sample and discusses the potential sources of error or bias within the dataset. The VEDB's potential applications are vast, including improving gaze-tracking methodologies, assessing spatiotemporal image statistics, and refining deep neural networks for scene and activity recognition. The VEDB is accessible through established open science platforms and is intended to be a living dataset with plans for expansion and community contributions. It is released with an emphasis on ethical considerations, such as participant privacy and the mitigation of potential biases. By providing a dataset grounded in real-world experiences and accompanied by extensive metadata and supporting code, the authors invite the research community to use and contribute to the VEDB, facilitating a richer understanding of visual perception and behavior in naturalistic settings.

Effects of simulated natural light brightness on visual perception in virtual reality forests: An eye-tracking study

Although natural light is essential for human health and well-being, the potential effects of different brightness levels of light on the visual perception of forests have not been discussed. Using controlled eye-tracking experiments, this study explored the impact of seven simulated natural brightness levels, from the darkest to the brightest, on the visual perception of 118 participants in a virtual reality (VR) forest environment. One of the most significant findings of this study was the marginal effect of natural light brightness levels on visual physiological stress in VR forests, with the pupillary unrest index decreasing significantly with the increase of natural light brightness; Secondly, the study analyzed the influence of natural light brightness levels in VR forests on the visual engagement behavior of eye tracking, that is, bright forest environments showed an overall trend associated with longer fixation duration, less saccade duration, and greater fixation direction ratio; Thirdly, in terms of visual perception evaluation, the study found an inverted U-shaped trend of mood, restorative perception, perceived safety, and natural light brightness level in VR forests. In addition, the study also found a significant correlation between visual physiological and psychological indicators in VR forest natural light visual perception experiments. These findings help us understand the visual perception effect of forest nature light exposure as a whole, and provided important clues and a basis for future research on improving the visual comfort of forest natural light.

Neural pathways and computations that achieve stable contrast processing tuned to natural scenes

Natural scenes are highly dynamic, challenging the reliability of visual processing. Yet, humans and many animals perform accurate visual behaviors, whereas computer vision devices struggle with rapidly changing background luminance. How does animal vision achieve this? Here, we reveal the algorithms and mechanisms of rapid luminance gain control in Drosophila, resulting in stable visual processing. We identify specific transmedullary neurons as the site of luminance gain control, which pass this property to direction-selective cells. The circuitry further involves wide-field neurons, matching computational predictions that local spatial pooling drive optimal contrast processing in natural scenes when light conditions change rapidly. Experiments and theory argue that a spatially pooled luminance signal achieves luminance gain control via divisive normalization. This process relies on shunting inhibition using the glutamate-gated chloride channel GluClα. Our work describes how the fly robustly processes visual information in dynamically changing natural scenes, a common challenge of all visual systems.

SENSE-Cog Lewy: Investigating the Impact of Sensory Loss on the Diagnosis, Clinical Features and Prognosis of Lewy Body Dementia

Abstract Background Lewy Body Dementia (LBD) accounts for 20% of the nearly 65,000 people with dementia in Ireland, but fewer than 5% of those affected receive a formal diagnosis. LBD includes both Parkinson’s disease dementia (PDD) and dementia with Lewy bodies (DLB) and can be characterised by fluctuating and progressive cognitive difficulties, vivid visual hallucinations and REM sleep behaviour disturbances. Sensory function such hearing, vision and olfactory function declines with age—but increasing evidence shows that abnormal patterns of sensory dysfunction can be one of the earliest clinical signs and predictors of progression of neurodegenerative diseases such as Lewy body dementia and Parkinson’s disease dementia. Methods A scoping review was undertaken using Embase, CINAHL, PsychINFO and PubMed. Only reports on people with LBD (DLB and PDD) from any stage, prodromal to late stage were considered. Papers primarily addressing other forms of neurocognitive disorders were excluded. Sensory loss was conceptualised as the loss of smell, vision and hearing. Two reviewers independently assessed each study for inclusion, and disagreements were resolved by a third reviewer. Results Reports on sensory loss in LBD were very few and most often were comparing sensory loss across different dementia types. Strong associations were observed between olfactory loss and particular visual impairment patterns and the severity of both cognitive and non-cognitive DLB symptoms. Olfactory impairment is a potential early biomarker of DLB and PDD and severity of olfactory dysfunction can predict cognitive decline. Visual hallucinations, for example, were found to be closely linked to visual impairment patterns such as pareidolia. Conclusion This study highlights a knowledge gap regarding the patterns of sensory loss in LBD and their relationship with cognitive and non-cognitive LBD symptoms. Sensory assessments represent potentially valuable diagnostic and prognosis tool in LBD, with further research required to understand the aetiological mechanisms underlying sensory impairment in LBD and other dementias.

Understanding the Impact of the Reality-Virtuality Continuum on Visual Search Using Fixation-Related Potentials and Eye Tracking Features

While Mixed Reality allows the seamless blending of digital content in users' surroundings, it is unclear if its fusion with physical information impacts users' perceptual and cognitive resources differently. While the fusion of digital and physical objects provides numerous opportunities to present additional information, it also introduces undesirable side effects, such as split attention and increased visual complexity. We conducted a visual search study in three manifestations of mixed reality (Augmented Reality, Augmented Virtuality, Virtual Reality) to understand the effects of the environment on visual search behavior. We conducted a multimodal evaluation measuring Fixation-Related Potentials (FRPs), alongside eye tracking to assess search efficiency, attention allocation, and behavioral measures. Our findings indicate distinct patterns in FRPs and eye-tracking data that reflect varying cognitive demands across environments. Specifically, AR environments were associated with increased workload, as indicated by decreased FRP - P3 amplitudes and more scattered eye movement patterns, impairing users' ability to identify target information efficiently. Participants reported AR as the most demanding and distracting environment. These insights inform design implications for MR adaptive systems, emphasizing the need for interfaces that dynamically respond to user cognitive load based on physiological inputs.