Eye Fixations Research Articles

Sensitivity of the Spatial Distribution of Fixations to Variations in the Type of Task Demand and Its Relation to Visual Entropy.

Ocular activity is known to be sensitive to variations in mental workload, and recent studies have successfully related the distribution of eye fixations to the mental load. This study aimed to verify the effectiveness of the spatial distribution of fixations as a measure of mental workload and its sensitivity to different types of demands imposed by the task: mental, temporal, and physical. To test the research hypothesis, two experimental studies were run: Experiment 1 evaluated the sensitivity of an index of spatial distribution (Nearest Neighbor Index; NNI) to changes in workload. A sample of 30 participants participated in a within-subject design with different types of task demands (mental, temporal, physical) applied to Tetris game; Experiment 2 investigated the accuracy of the index through the analysis of 1-min epochs during the execution of a visual-spatial task (the “spot the differences” puzzle game). Additionally, NNI was compared to a better-known ocular mental workload index, the entropy rate. The data analysis showed a relation between the NNI and the different workload levels imposed by the tasks. In particular: Experiment 1 demonstrated that increased difficulty, due to higher temporal demand, led to a more dispersed pattern with respect to the baseline, whereas the mental demand led to a more grouped pattern of fixations with respect to the baseline; Experiment 2 indicated that the entropy rate and the NNI show a similar pattern over time, indicating high mental workload after the first minute of activity. That suggests that NNI highlights the greater presence of fixation groups and, accordingly, the entropy indicates a more regular and orderly scanpath. Both indices are sensitive to changes in workload and they seem to anticipate the drop in performance. However, the entropy rate is limited by the use of the areas of interest, making it impossible to apply it in dynamic contexts. Conversely, NNI works with the entire scanpath and it shows sensitivity to different types of task demands. These results confirm the NNI as a measure applicable to different contexts and its potential use as a trigger in adaptive systems implemented in high-risk settings, such as control rooms and transportation systems.

Message framing, non-conscious perception and effectiveness in non-profit advertising. Contribution by neuromarketing research

Advertising for non-profit organizations through television commercials is a valuable means of communication to raise awareness and receive donations. When it comes to social aspects, personal attitudes such as empathy are significant for reinforcing the intention to donate; and the study of eliciting emotions has critical attention in the literature, especially some types of emotion, such as guilt which mediates empathy. Different methodologies have been used to measure consumer emotions when faced with TV ads stimuli: mainly traditional techniques such as interviews or questionnaires after the ads viewing. In the last ten years, there has also been a great interest in new neuroscience techniques applied to measure emotional and cognitive reactions by physiological signals, frame by frame. Our research has applied neuromarketing technologies during the observation of a UNHCR commercial promoting legacy calls. The objective was to study cognitive and emotional reactions in order to increase the effectiveness whilst having the possibility to verify the results by measuring the benefits in terms of calls from contributors. The purpose of this research is to empirically prove the impact in calls thanks to changes in the message framing strategy in non-profit advertising suggested and measured by neuromarketing techniques. Particularly we measured the cerebral activity through an electroencephalogram to obtain an Approach-Withdrawal Index (AW); the heart rate and galvanic skin response through different sensors in the palm of one hand, to obtain an Emotional Index (EI), and finally, eye fixations through an eye tracker device to obtain the visual attention on key visual areas of the ads. After these indicators’ recordings on a sample of subjects, some suggestions to modify the advertising were made to create a more effective campaign. The results compared, those elicited by the first version of the spot (LVE) and those by the second version (HVE), confirmed that (1) the number of sellable and legacy calls increased with the message framing strategy modified in the second spot (HVE), (2) a lower cognitive and emotional reactions have been obtained in the final section of HVE, (3) the visual attention on the key information of the phone number to call, in the final call to action frames(CTA), was higher in HVE than in the first version of the spot (LVE), (4) the cognitive approach increased during the same CTA frames in HVE.

A Neuromorphic Proto-Object Based Dynamic Visual Saliency Model With a Hybrid FPGA Implementation.

Computing and attending to salient regions of a visual scene is an innate and necessary preprocessing step for both biological and engineered systems performing high-level visual tasks including object detection, tracking, and classification. Computational bandwidth and speed are improved by preferentially devoting computational resources to salient regions of the visual field. The human brain computes saliency effortlessly, but modeling this task in engineered systems is challenging. We first present a neuromorphic dynamic saliency model, which is bottom-up, feed-forward, and based on the notion of proto-objects with neurophysiological spatio-temporal features requiring no training. Our neuromorphic model outperforms state-of-the-art dynamic visual saliency models in predicting human eye fixations (i.e., ground truth saliency). Secondly, we present a hybrid FPGA implementation of the model for real-time applications, capable of processing 112×84 resolution frames at 18.71 Hz running at a 100 MHz clock rate - a 23.77× speedup from the software implementation. Additionally, our fixed-point model of the FPGA implementation yields comparable results to the software implementation.

Ocular fixations modulate audiovisual semantic congruency when standing in an upright position

Introduction: Multisensory audiovisual semantic congruency is the process by which visual information is perceived as integrated to auditory stimuli, because both coincide in terms of simultaneity and semantic correspondence. This study was aimed at establishing whether visual percepts, which semantically correspond to auditory stimuli, are associated with ocular fixations in modulating bottom-up areas while keeping a body posture alignment between the up-direction and the idiotropic axes, as well as in another orientation corresponding to a vectorial opposition between the up-direction and the head idiotropic axis. Method: Two groups (one for each position) were selected from a sample of 88 people. A bistable image was presented on a screen of a fixed 120 Hz eye-tracker device, providing background auditory stimuli so as to establish semantic congruencies and their relations to ocular fixations. Results: It was found that audiovisual semantic congruency is associated with fixations when idiotropic vectors are aligned with the up direction. Fixations manifested in bottom-up modulating areas are not associated with multisensory audiovisual semantic congruency when the head idiotropic vector is parallel with the gravity vector. Eye fixations decrease significantly if the head idiotropic axis is aligned with the gravity vector. Conclusion: It is concluded that body position can affect visual perceptual processes involved in the occurrence of semantic congruency.

A Study on Check of Child's Condition during Nap of Childcare Professionals based on Eye Fixation Behavior

A Study on Check of Child's Condition during Nap of Childcare Professionals based on Eye Fixation Behavior

Features of digital information perception by operators with different color schemes of the stimulus material

The rapid development of aviation technology entails the need to increase the quality of ergonomic support. This is due to the fact that for the safe implementation of activities, the pilot has to use the entire amount of attention, not rarely, at the limit of his capabilities. The color of the instrument scales, the contrast of the information feed, and other information perception conditions can significantly complicate the evaluation of the flight instrument readings. This is especially true with the transition of most modern aircraft from analog display of instrument readings to digital. The study examines the features of perception of digital information by operators of aviation profile with different color background of the stimulus material. The analysis of the results of the solution by operators of 3 Schulte tables and 3 SchultePlatonov tables on the combined hardware complex NS-Psychotest with the system of fixing the coordinates of the eye-stationary eye tracking RED250mobile eye tracking device. When performing the eye search function, the number of visual fixations and the task completion time were calculated. It was found that when searching for digital values on Schulte tables with a white background, the number of eye fixations was less than when performing a similar task on black-and-red SchultePlatonov tables. Accordingly, it also took less time to solve black-and-white tables. A trend was found showing that the search for digital values represented in the SchultePlatonov tables on a red background was carried out by operators faster than on a black background. Further study of this topic can contribute to the development of proposals for ergonomic support of aircraft, which in turn will help to maintain the reserves of attention of operators in a continuous stream of incoming data (2 figures, 1 table, bibliography: 13 refs).

Computer-aided autism diagnosis based on visual attention models using eye tracking

An advantage of using eye tracking for diagnosis is that it is non-invasive and can be performed in individuals with different functional levels and ages. Computer/aided diagnosis using eye tracking data is commonly based on eye fixation points in some regions of interest (ROI) in an image. However, besides the need for every ROI demarcation in each image or video frame used in the experiment, the diversity of visual features contained in each ROI may compromise the characterization of visual attention in each group (case or control) and consequent diagnosis accuracy. Although some approaches use eye tracking signals for aiding diagnosis, it is still a challenge to identify frames of interest when videos are used as stimuli and to select relevant characteristics extracted from the videos. This is mainly observed in applications for autism spectrum disorder (ASD) diagnosis. To address these issues, the present paper proposes: (1) a computational method, integrating concepts of Visual Attention Model, Image Processing and Artificial Intelligence techniques for learning a model for each group (case and control) using eye tracking data, and (2) a supervised classifier that, using the learned models, performs the diagnosis. Although this approach is not disorder-specific, it was tested in the context of ASD diagnosis, obtaining an average of precision, recall and specificity of 90%, 69% and 93%, respectively.

Horizontal eye movements foster approach to negative pictures but do not change emotional valence: A dopaminergic regulation hypothesis

A new dopaminergic regulation hypothesis is proposed based on two experiments exploring eye-movement effects. In the Eye Movement Desensitization and Reprocessing (EMDR) and Saccade-Induced Retrieval Enhancement (SIRE) domains, eye-movement mechanisms are mainly studied with explicit measures. Here implicit and explicit measures of emotion and memory for positive and negative pictures were investigated after eye movements or fixation in extreme right-handers. Eye movements enhanced explicit recognition predominantly for negative pictures. The absence of implicit repetition priming in both experiments supported a dissociation between implicit and explicit memory. Motivational eye-movement effects emerged but implicit and explicit affect remained unchanged. Experiment 2 revealed, after initial freezing to negative pictures, an acceleration, particularly of approach responses. Eye movements are postulated to foster approach towards negative memories, and promote, though dopaminergic pathways from the Superior Colliculus, enhanced explicit memory and active emotion regulation, primarily in persons with a collateralization of eye and dopamine dominance.

The Effects of Language Barriers and Time Constraints on Online Learning Performance: An Eye-Tracking Study.

The goal of this study is to model the effect of language use and time pressure on English as a first language (EFL) and English as a second language (ESL) students by measuring their eye movements in an on-screen, self-directed learning environment. Online learning is becoming integrated into learners' daily lives due to the flexibility in scheduling and location that it offers. However, in many cases, the online learners often have no interaction with one another or their instructors, making it difficult to determine how the learners are reading the materials and whether they are learning effectively. Furthermore, online learning may pose challenges to those who face language barriers or are under time pressure. The effects of two factors, language use (EFL vs. ESL) and time constraints (high vs. low time pressure), were investigated during the presentation of online materials. The effects were analyzed based on eye movement measures (eye fixation rate-the total number of eye fixations divided by the task duration and gaze entropy) and behavioral measures (correct rate and task completion time). The results show that the ESL students had higher eye fixation rates and longer task completion times than the EFL students. Moreover, high time pressure resulted in high fixation rates, short task completion time, low correct rates, and high gaze entropy. The results suggest the possibility of using unobtrusive eye movement measures to develop ways to better assist those who struggle with learning in the online environment.

Jurors’ emotional state, attentional focus, and judicial judgment in a criminal court

ABSTRACT In order to consider the relevant relationships between emotion, information processing and judicial judgment, this study evaluated the impact of positive (amusement), negative (sadness) or neutral mood induction on 128 mock jurors’ visual attentional focus, as measured by their eye fixations on the face of a witness filmed while giving testimony in a criminal court. Participants then rated their perceptions of the witness's and their own emotions on the Differential Emotional Scale, before indicating their final judicial judgment. As expected, results showed that sadness can favour information processing in a in more effortful mode, with more steady visual attention, while a positive emotional state such as amusement can favour information processing based more on the witness's emotions, a source of useful clues for establishing the judicial judgment. These results are discussed in relation to how the cognitive approach can shed light on the processes underlying judicial judgment.

Interocular Suppression in Primary Visual Cortex in Strabismus.

People with strabismus acquired during childhood do not experience diplopia (double vision). To investigate how perception of the duplicate image is suppressed, we raised two male monkeys with alternating exotropia by disinserting the medial rectus muscle in each eye at age four weeks. Once the animals were mature, they were brought to the laboratory and trained to fixate a small spot while recordings were made in primary visual cortex (V1). Drifting gratings were presented to the receptive fields of 500 single neurons for eight interleaved conditions: (1) right eye monocular; (2) left eye monocular; (3) right eye's field, right eye fixating; (4) right eye's field, left eye fixating; (5) left eye's field, right eye fixating; (6) left eye's field, left eye fixating; (7) both eyes' fields, right eye fixating; (8) both eyes' fields, left eye fixating. As expected, ocular dominance histograms showed a monocular bias compared with normal animals, but many cells could still be driven via both eyes. Overall, neuronal responses were not affected by switches in ocular fixation. Individual neurons exhibited binocular interactions, but mean population indices indicated no net interocular suppression or facilitation. Even neurons located in cortex with reduced cytochrome oxidase (CO) activity, representing portions of the nasal visual field where perception is suppressed during binocular viewing, showed no net inhibition. These data indicate that V1 neurons do not appear to reflect strabismic suppression and therefore the elimination of diplopia is likely to be mediated at a higher cortical level.SIGNIFICANCE STATEMENT In patients with strabismus, images fall on non-corresponding points in the two retinas. Only one image is perceived, because signals emanating from the other eye that convey the duplicate image are suppressed. The benefit is that diplopia is prevented, but the penalty is that the visual feedback required to adjust eye muscle tone to realign the globes is eliminated. Here, we report the first electrophysiological recordings from the primary visual cortex (V1) in awake monkeys raised with strabismus. The experiments were designed to reveal how perception of double images is avoided.

Visual Neuroscience Methods for Marmosets: Efficient Receptive Field Mapping and Head-Free Eye Tracking.

The marmoset has emerged as a promising primate model system, in particular for visual neuroscience. Many common experimental paradigms rely on head fixation and an extended period of eye fixation during the presentation of salient visual stimuli. Both of these behavioral requirements can be challenging for marmosets. Here, we present two methodological developments, each addressing one of these difficulties. First, we show that it is possible to use a standard eye-tracking system without head fixation to assess visual behavior in the marmoset. Eye-tracking quality from head-free animals is sufficient to obtain precise psychometric functions from a visual acuity task. Second, we introduce a novel method for efficient receptive field (RF) mapping that does not rely on moving stimuli but uses fast flashing annuli and wedges. We present data recorded during head-fixation in areas V1 and V6 and show that RF locations are readily obtained within a short period of recording time. Thus, the methodological advancements presented in this work will contribute to establish the marmoset as a valuable model in neuroscience.

FixationNet: Forecasting Eye Fixations in Task-Oriented Virtual Environments.

Human visual attention in immersive virtual reality (VR) is key for many important applications, such as content design, gaze-contingent rendering, or gaze-based interaction. However, prior works typically focused on free-viewing conditions that have limited relevance for practical applications. We first collect eye tracking data of 27 participants performing a visual search task in four immersive VR environments. Based on this dataset, we provide a comprehensive analysis of the collected data and reveal correlations between users' eye fixations and other factors, i.e. users' historical gaze positions, task-related objects, saliency information of the VR content, and users' head rotation velocities. Based on this analysis, we propose FixationNet - a novel learning-based model to forecast users' eye fixations in the near future in VR. We evaluate the performance of our model for free-viewing and task-oriented settings and show that it outperforms the state of the art by a large margin of 19.8% (from a mean error of 2.93° to 2.35°) in free-viewing and of 15.1% (from 2.05° to 1.74°) in task-oriented situations. As such, our work provides new insights into task-oriented attention in virtual environments and guides future work on this important topic in VR research.

Investigating the Use of Eye Fixation Data for Emotion Classification in VR

Eye-tracking technology has become popular recently and widely used in research on emotion recognition since its usability. In this paper, we presented a preliminary investigation on a novelty approach for detecting emotions using eye-tracking data in virtual reality (VR) to classify 4-quadrant of emotions according to russell’scircumplex model of affects. A presentation of 3600 videos is used as the experiment stimuli to evoke the emotions of the user in VR. An add-on eye-tracker within the VR headset is used for the recording and collecting device of eye-tracking data. Fixation data is extracted and chosen as the eye feature used in this investigation. The machine learning classifier is support vector machine (SVM) with radial basis function (RBF) kernel. The best classification accuracy achieved is 69.23%. The findings showed that emotion classification using fixation data has promising results in the prediction accuracy from a four-class random classification.

E-스포츠에서 숙련성과 상태불안상황에 따른 시선도약과 시선고정 차이 검증

본 연구의 목적은 e-스포츠에서 상태불안과 숙련성에 따라 시선도약과 시선고정의 차이를 살펴보는 것이다. 이를 위해 배틀그라운드 통계 홈페이지를 참고하여 랭킹이 상위 18% 이상인 숙련자 10명과 하위 30%미만인 비숙련자 10명, 총 20명을 대상으로 연구를 진행하였다. 상태불안은 심박수를 통해 측정하였고, 참여자의 시선도약과 시선고정 측정은 아이트랙(Tobii Pro Glasses 2)을 사용하였다. 연구결과 상태불안에 따라 숙련자와 비숙련자의 시선이동과 시선고정에서 차이가 존재하였다. 상태불안이 높을수록 숙련자가 비숙련자에 비해 시선이동이 낮게 나타났고, 시선고정에서도 높은 상태불안에서 숙련자의 시선고정 시간이 비숙련자보다 짧았다. 본 연구결과를 바탕으로 e-스포츠에서 지각연구의 방향성에 대해서 논하였고, 연구를 진행하면서 제기된 한계점 또한 제시하였다.

Refractive disorders in children

According to current estimations, globally, there are around 150 million people with an uncorrected refractive disorder, which means 27% of the world’s population. Approximately 1.4 million of these are children and have a milder or more severe form of visual dysfunction secondary to refractive errors. Since 1990, refractive errors are considered to be a public health problem among children and cause visual dysfunction, with a prevalence of up to 43%. Vision maturation occurs in early childhood, when all the senses and motor skills work together to acquire language, first ideas about the environment and all the elements that define the person himself. Sight is a contributory perceptual system for the cognitive, social, sensory-motor development and for the assemblage of information about the environment. In the first years of life, the child increasingly discovers complex activities, requiring the ability to change the eyes fixation in space from one point to another and a normal binocular motility.

Evaluation of cerebral visual functions in low myopic adolescents

AIM: To explore whether low myopia would affect cerebral visual functions by comparing perceptual eye position (PEP), fixation stability and stereoacuity tests between low myopic and normal adolescents. METHODS: Totally 120 adolescents matched in age and gender participated in our study. Subjects were divided into three groups according to their refractive states. The cerebral visual functions tested in our study included perceptual eye position (PEP), fixation stability and stereoacuity. Stereoacuity tests involved in our study could be categorized into two parts. The first part was classical stereo tests including Titmus and synoptophore stereo test. The second part was 3D random-dot test for zero-order stereoacuity (hereinafter as zero-order test) at different viewing distances (0.8 m and 1.5 m). RESULTS: The deviation of horizontal PEP was significantly larger in non-anisometropia when compared to control group. Both horizontal and vertical PEP bias pixels were significantly larger in anisometropia group. Both non-anisometropia group and anisometropia group had more trouble in holding their fixation stable. Moreover, anisometropia group had more abnormal results than other two groups. And in zero-order test at 1.5 m, both non-anisometropia and anisometropia had more abnormal results in stereoacuity than control group. The correlation between fixation stability and near stereoacuity (Titmus and zero-order stereoacuity at 0.8 m) was weak and positive. CONCLUSION: Low myopic adolescents still have certain defects in cerebral visual functions. Examinations used in our study are useful in assessing cerebral visual functions. They could provide better follow-up evaluation and solid ground for further specific treatments in treating defects of cerebral visual functions. So far, local retinal environment has been the focus of the development in myopia. Our results suggested that researchers might pay more attention on visual cortex in studying the mechanisms of myopia in the near future.

Pictorial low-level features in mental images: evidence from eye fixations.

It is known that eye movements during object imagery reflect areas visited during encoding. But will eye movements also reflect pictorial low-level features of imagined stimuli? In this paper, three experiments are reported in which we investigate whether low-level properties of mental images elicit specific eye movements. Based on the conceptualization of mental images as depictive representations, we expected low-level visual features to influence eye fixations during mental imagery, in the absence of a visual input. In a first experiment, twenty-five participants performed a visual imagery task with high vs. low spatial frequency and high vs. low contrast gratings. We found that both during visual perception and during mental imagery, first fixations were more often allocated to the low spatial frequency-high contrast grating, thus showing that eye fixations were influenced not only by physical properties of visual stimuli but also by its imagined counterpart. In a second experiment, twenty-two participants imagined high contrast and low contrast stimuli that they had not encoded before. Again, participants allocated more fixations to the high contrast mental images than to the low contrast mental images. In a third experiment, we ruled out task difficulty as confounding variable. Our results reveal that low-level visual features are represented in the mind's eye and thus, they contribute to the characterization of mental images in terms of how much perceptual information is re-instantiated during mental imagery.

How Does Wearing a Facecover Influence the Eye Movement Pattern in Times of COVID-19?

BackgroundSince the emergence of the COVID-19 pandemic facecovers have become a common sight. The effect of facecovers on the gaze when looking at faces has not been assessed yet.ObjectiveThe aim of the present study is to investigate a potential difference in eye movement pattern in observes which are exposed to images showing a face without and with facecover to identify if there is truly a change of gaze when identifying (masked) facial features.Materials and MethodsThe eye movement of a total of 64 study participants (28 males and 36 females) with a mean age of 31.84±9.0 years was analyzed in this cross-sectional observational study. Eye movement analysis was conducted based on positional changes of eye features within an x- and y- coordinate system while two images (face without/with facecover) were displayed for 8 seconds.ResultsThe results of this study revealed that the sequence of focussing on facial regions was not altered when wearing a facecover and followed the sequence: perioral, nose, periorbital. Wearing a facecover significantly increased the time of focussing on the periorbital region and increased also the number of repeated eye fixations during the interval of visual stimulus presentation. No statistically significant differences were observed between male and female participants in their eye movement pattern across all investigated variables with p > 0.433.ConclusionAesthetic practitioners could utilized the presented data and develop marketing and treatment strategies which majorly target the periorbital area understanding the altered eye movement pattern in times of COVID-19.

A passive BCI for monitoring the intentionality of the gaze-based moving object selection

Objective. The use of an electroencephalogram (EEG) anticipation-related component, the expectancy wave (E-wave), in brain–machine interaction was proposed more than 50 years ago. This possibility was not explored for decades, but recently it was shown that voluntary attempts to select items using eye fixations, but not spontaneous eye fixations, are accompanied by the E-wave. Thus, the use of the E-wave detection was proposed for the enhancement of gaze interaction technology, which has a strong need for a mean to decide if a gaze behavior is voluntary or not. Here, we attempted at estimating whether this approach can be used in the context of moving object selection through smooth pursuit eye movements. Approach. Eighteen participants selected, one by one, items which moved on a computer screen, by gazing at them. In separate runs, the participants performed tasks not related to voluntary selection but also provoking smooth pursuit. A low-cost consumer-grade eye tracker was used for item selection. Main results. A component resembling the E-wave was found in the averaged EEG segments time-locked to voluntary selection events of every participant. Linear discriminant analysis with shrinkage regularization classified the intentional and spontaneous smooth pursuit eye movements, using single-trial 300 ms long EEG segments, significantly above chance in eight participants. When the classifier output was averaged over ten subsequent data segments, median group ROC AUC of 0.75 was achieved. Significance. The results suggest the possible usefulness of the E-wave detection in the gaze-based selection of moving items, e.g. in video games. This technique might be more effective when trial data can be averaged, thus it could be considered for use in passive interfaces, for example, in estimating the degree of the user’s involvement during gaze-based interaction.