Gaze Targets Research Articles

Effect of allocentric landmarks on primate gaze behavior in a cue conflict task.

The relative contributions of egocentric versus allocentric cues on goal-directed behavior have been examined for reaches, but not saccades. Here, we used a cue conflict task to assess the effect of allocentric landmarks on gaze behavior. Two head-unrestrained macaques maintained central fixation while a target flashed in one of eight radial directions, set against a continuously present visual landmark (two horizontal/vertical lines spanning the visual field, intersecting at one of four oblique locations 11° from the target). After a 100-ms delay followed by a 100-ms mask, the landmark was displaced by 8° in one of eight radial directions. After a second delay (300-700 ms), the fixation point extinguished, signaling for a saccade toward the remembered target. When the landmark was stable, saccades showed a significant but small (mean 15%) pull toward the landmark intersection, and endpoint variability was significantly reduced. When the landmark was displaced, gaze endpoints shifted significantly, not toward the landmark, but partially (mean 25%) toward a virtual target displaced like the landmark. The landmark had a larger influence when it was closer to initial fixation, and when it shifted away from the target, especially in saccade direction. These findings suggest that internal representations of gaze targets are weighted between egocentric and allocentric cues, and this weighting is further modulated by specific spatial parameters.

Application of eye tracking in medicine: A survey, research issues and challenges

The performance and quality of medical procedures and treatments are inextricably linked to technological development. The application of more advanced techniques provides the opportunity to gain wider knowledge and deeper understanding of the human body and mind functioning. The eye tracking methods used to register eye movement to find the direction and targets of a person's gaze are well in line with the nature of the topic. By providing methods for capturing and processing images of the eye it has become possible not only to reveal abnormalities in eye functioning but also to conduct cognitive studies focused on learning about peoples’ emotions and intentions. The usefulness of the application of eye tracking technology in medicine was proved in many research studies. The aim of this paper is to give an insight into those studies and the way they utilize eye imaging in medical applications. These studies were differentiated taking their purpose and experimental paradigms into account. Additionally, methods for eye movement visualization and metrics for its quantifying were presented. Apart from presenting the state of the art, the aim of the paper was also to point out possible applications of eye tracking in medicine that have not been exhaustively investigated yet, and are going to be a perspective long-term direction of research.

A propósito de los desafíos docentes en el tratamiento del currículum universitario en la Postmodernidad

From all times, education has been a motive of social interest, among policies, approaches and constant changes, it has remained with its two stellar figures: teachers and students, being the target of society's gaze as judge and part of the same. The present study was created with the purpose of rethinking in the university curriculum, reviewing the route of learning and the territories that still have to be covered, as the first challenge of the university teacher. Addressing the issue moved away from making an unnecessary and unfair criticism of university education that has accepted challenges and has overcome them, the idea, rather, had to focus on the sector, which in the light of postmodernism, has taken a position lacking conscience in the face of knowledge and the contract he has with society. A study based on observations, sounding, testimonies and bibliographic review, taking as reference Universities of Guayaquil, Ambato, Babahoyo and Loja, allowed to detect a sample of the imminent need to refresh the conduction of the curriculum in the university classroom, from the role of the teacher, Who better to enhance meaningful learning, with results of authentic performances in a climate of healthy coexistence and union in diversity

Gaze behavior during 3-D face identification is depth cue invariant.

Gaze behavior during scene and object recognition can highlight the relevant information for a task. For example, salience maps-highlighting regions that have heightened luminance, contrast, color, etc. in a scene-can be used to predict gaze targets. Certain tasks, such as face recognition, result in a typical pattern of fixations on high salience features. While local salience of a 2-D feature may contribute to gaze behavior and object recognition, we are perfectly capable of recognizing objects from 3-D depth cues devoid of meaningful 2-D features. Faces can be recognized from pure texture, binocular disparity, or structure-from-motion displays (Dehmoobadsharifabadi & Farivar, 2016; Farivar, Blanke, & Chaudhuri, 2009; Liu, Collin, Farivar, & Chaudhuri, 2005), and yet these displays are devoid of local salient 2-D features. We therefore sought to determine whether gaze behavior is driven by an underlying 3-D representation that is depth-cue invariant or depth-cue specific. By using a face identification task comprising morphs of 3-D facial surfaces, we were able to measure identification thresholds and thereby equate for task difficulty across different depth cues. We found that gaze behavior for faces defined by shading and texture cues was highly comparable, but we observed some deviations for faces defined by binocular disparity. Interestingly, we found no effect of task difficulty on gaze behavior. The results are discussed in the context of depth-cue invariant representations for facial surfaces, with gaze behavior being constrained by low-level limits of depth extraction from specific cues such as binocular disparity.

Gaze-informed, task-situated representation of space in primate hippocampus during virtual navigation.

To elucidate how gaze informs the construction of mental space during wayfinding in visual species like primates, we jointly examined navigation behavior, visual exploration, and hippocampal activity as macaque monkeys searched a virtual reality maze for a reward. Cells sensitive to place also responded to one or more variables like head direction, point of gaze, or task context. Many cells fired at the sight (and in anticipation) of a single landmark in a viewpoint- or task-dependent manner, simultaneously encoding the animal’s logical situation within a set of actions leading to the goal. Overall, hippocampal activity was best fit by a fine-grained state space comprising current position, view, and action contexts. Our findings indicate that counterparts of rodent place cells in primates embody multidimensional, task-situated knowledge pertaining to the target of gaze, therein supporting self-awareness in the construction of space.

Appearance-Based Gaze Estimation via Uncalibrated Gaze Pattern Recovery.

Aiming at reducing the restrictions due to person/scene dependence, we deliver a novel method that solves appearance-based gaze estimation in a novel fashion. First, we introduce and solve an "uncalibrated gaze pattern" solely from eye images independent of the person and scene. The gaze pattern recovers gaze movements up to only scaling and translation ambiguities, via nonlinear dimension reduction and pixel motion analysis, while no training/calibration is needed. This is new in the literature and enables novel applications. Second, our method allows simple calibrations to align the gaze pattern to any gaze target. This is much simpler than conventional calibrations which rely on sufficient training data to compute person and scene-specific nonlinear gaze mappings. Through various evaluations, we show that: 1) the proposed uncalibrated gaze pattern has novel and broad capabilities; 2) the proposed calibration is simple and efficient, and can be even omitted in some scenarios; and 3) quantitative evaluations produce promising results under various conditions.

Control of gaze while walking: Task structure, reward, and uncertainty.

While it is universally acknowledged that both bottom up and top down factors contribute to allocation of gaze, we currently have limited understanding of how top-down factors determine gaze choices in the context of ongoing natural behavior. One purely top-down model by Sprague, Ballard, and Robinson (2007) suggests that natural behaviors can be understood in terms of simple component behaviors, or modules, that are executed according to their reward value, with gaze targets chosen in order to reduce uncertainty about the particular world state needed to execute those behaviors. We explore the plausibility of the central claims of this approach in the context of a task where subjects walk through a virtual environment performing interceptions, avoidance, and path following. Many aspects of both walking direction choices and gaze allocation are consistent with this approach. Subjects use gaze to reduce uncertainty for task-relevant information that is used to inform action choices. Notably the addition of motion to peripheral objects did not affect fixations when the objects were irrelevant to the task, suggesting that stimulus saliency was not a major factor in gaze allocation. The modular approach of independent component behaviors is consistent with the main aspects of performance, but there were a number of deviations suggesting that modules interact. Thus the model forms a useful, but incomplete, starting point for understanding top-down factors in active behavior.

Brief Report: Using a Point-of-View Camera to Measure Eye Gaze in Young Children with Autism Spectrum Disorder During Naturalistic Social Interactions: A Pilot Study.

Children with autism spectrum disorder (ASD) show reduced gaze to social partners. Eye contact during live interactions is often measured using stationary cameras that capture various views of the child, but determining a child's precise gaze target within another's face is nearly impossible. This study compared eye gaze coding derived from stationary cameras to coding derived from a "point-of-view" (PoV) camera on the social partner. Interobserver agreement for gaze targets was higher using PoV cameras relative to stationary cameras. PoV camera codes, but not stationary cameras codes, revealed a difference between gaze targets of children with ASD and typically developing children. PoV cameras may provide a more sensitive method for measuring eye contact in children with ASD during live interactions.

The Eyes Are the Windows to the Mind

Eye gaze is a potent source of social information with direct eye gaze signaling the desire to approach and averted eye gaze signaling avoidance. In the current work, we proposed that eye gaze signals whether or not to impute minds into others. Across four studies, we manipulated targets' eye gaze (i.e., direct vs. averted eye gaze) and measured explicit mind ascriptions (Study 1a, Study 1b, and Study 2) and beliefs about the likelihood of targets having mind (Study 3). In all four studies, we find novel evidence that the ascription of sophisticated humanlike minds to others is signaled by the display of direct eye gaze relative to averted eye gaze. Moreover, we provide evidence suggesting that this differential mentalization is due, at least in part, to beliefs that direct gaze targets are more likely to instigate social interaction. In short, eye contact triggers mind perception.

Prior expectations about where other people are likely to direct their attention systematically influence gaze perception.

Different locations in the visual environment vary greatly in terms of how likely they are to draw a person's attention. When inferring the most likely target of another person's gaze, it would therefore be a reasonable strategy to incorporate expectations about the relative visual salience of these various locations, weighing this prior knowledge against incoming social signals (e.g., eye cues). This Bayesian approach to modeling gaze perception has informed computer vision techniques, but whether this model accounts well for human performance remains an untested hypothesis. We present subjects with a “gazer” fixating his eyes on various locations on a two-dimensional surface, and project arbitrary photographic images onto that surface. Subjects judge where the gazer is looking in each image. A full Bayesian model, which takes image salience information into account, fits subjects' gaze judgments better than a reduced model that only considers the perceived direction of the gazer's eyes. Varying the amount of time the subject is allowed to view the gazer reveals that center bias tends to dominate gaze judgments early, whereas salient features specific to the projected image influence judgments at longer viewing durations.

Sensorimotor Decoupling Contributes to Triadic Attention: A Longitudinal Investigation of Mother-Infant-Object Interactions.

Previous developmental accounts of joint object activity identify a qualitative "shift" around 9-12 months. In a longitudinal study of 26 dyads, videos of joint object interactions at 4, 6, 9, and 12 months were coded for all targets of gaze and manual activity (at 10 Hz). At 12 months, infants distribute their sensorimotor modalities between objects handled by the parent and others controlled by the infant. Analyses reveal novel trajectories in distributed joint object activity across the 1st year. At 4 months, infants predominantly look at and manipulate a single object, typically held by their mothers. Between 6 and 9 months, infants increasingly decouple their visual and haptic modalities and distribute their attention between objects held by their mothers and by themselves. These previously unreported developments in the distribution of multimodal object activity might "bridge the gap" to coordinated joint activity between 6 and 12 months.

Covert preparation of a manual response in a 'go'/'no-go' saccadic task is driven by execution of the eye movement and not by visual stimulus occurrence.

It has been recently demonstrated that visually guided saccades are linked to changes in muscle excitability in the relaxed upper limb, which are compatible with a covert motor plan encoding a hand movement toward the gaze target. In this study we investigated whether these excitability changes are time locked to the visual stimulus, as predicted by influential attention models, or are strictly dependent on saccade execution. Single-pulse transcranial magnetic stimulation was applied to the motor cortex at eight different time delays during a ‘go’/‘no-go’ task, which involved overt or covert orienting of attention. By analyzing the time course of excitability in three hand muscles, synchronized with the onset of either the attentional cue or the eye movement, we demonstrated that side- and muscle-specific excitability changes were strictly time locked to the saccadic response and were not correlated to the onset of the visual attentive stimulus. Furthermore, muscle excitability changes were absent following a covert shift of attention. We conclude that a sub-threshold manual motor plan is automatically activated by the saccade decision-making process, as part of a covert eye-hand coordination program. We found no evidence for a representation of spatial attention within the upper limb motor map.

Look together: analyzing gaze coordination with epistemic network analysis.

When conversing and collaborating in everyday situations, people naturally and interactively align their behaviors with each other across various communication channels, including speech, gesture, posture, and gaze. Having access to a partner's referential gaze behavior has been shown to be particularly important in achieving collaborative outcomes, but the process in which people's gaze behaviors unfold over the course of an interaction and become tightly coordinated is not well understood. In this paper, we present work to develop a deeper and more nuanced understanding of coordinated referential gaze in collaborating dyads. We recruited 13 dyads to participate in a collaborative sandwich-making task and used dual mobile eye tracking to synchronously record each participant's gaze behavior. We used a relatively new analysis technique—epistemic network analysis—to jointly model the gaze behaviors of both conversational participants. In this analysis, network nodes represent gaze targets for each participant, and edge strengths convey the likelihood of simultaneous gaze to the connected target nodes during a given time-slice. We divided collaborative task sequences into discrete phases to examine how the networks of shared gaze evolved over longer time windows. We conducted three separate analyses of the data to reveal (1) properties and patterns of how gaze coordination unfolds throughout an interaction sequence, (2) optimal time lags of gaze alignment within a dyad at different phases of the interaction, and (3) differences in gaze coordination patterns for interaction sequences that lead to breakdowns and repairs. In addition to contributing to the growing body of knowledge on the coordination of gaze behaviors in joint activities, this work has implications for the design of future technologies that engage in situated interactions with human users.

Saccadic movement deficiencies in adults with ADHD tendencies.

The goal of the present study was to explore deficits in gaze detection and emotional value judgment during a saccadic eye movement task in adults with attention deficit/hyperactivity disorder (ADHD) tendencies. Thirty-two participants, consisting of 16 ADHD tendencies and 16 controls, were recruited from a pool of 243 university students. Among the many problems in adults with ADHDs, our research focused on the deficits in the processing of nonverbal cues, such as gaze direction and the emotional value of others' faces. In Experiment 1, a cue display containing a face with emotional value and gaze direction was followed by a target display containing two faces located on the left and right side of the display. The participant's task was to make an anti-saccade opposite to the gaze direction if the cue face was not emotionally neutral. ADHD tendencies showed more overall errors than controls in making anti-saccades. Based on the hypothesis that the exposure duration of the cue display in Experiment 1 may have been too long, we presented the cue and target display simultaneously to prevent participants from preparing saccades in advance. Participants in Experiment 2 were asked to make either a pro-saccade or an anti-saccade depending on the emotional value of the central cue face. Interestingly, significant group differences were observed for errors of omission and commission. In addition, a significant three-way interaction among groups, cue emotion, and target gaze direction suggests that the emotional recognition and gaze control systems might somehow be interconnected. The result also shows that ADHDs are more easily distracted by a task-irrelevant gaze direction. Taken together, these results suggest that tasks requiring both response inhibition (anti-saccade) and gaze-emotion recognition might be useful in developing a diagnostic test for discriminating adults with ADHDs from healthy adults.

Bicyclists’ visual strategies when conducting self-paced vs. system-paced smartphone tasks in traffic

Visual distraction among cyclists interacting with their mobile phones is a growing concern. Yet, very little research has actually investigated how cyclists apply visual strategies and adapt task execution depending on the traffic situation. The aim of this study is to investigate visual behaviour of cyclists when conducting self-paced (initiated by the cyclist) vs. system-paced (initiated by somebody else) smartphone tasks in traffic.Twenty-two cyclists completed a track in real traffic while listening to music, receiving and making calls, receiving and sending text messages, and searching for information on the internet. The route and the types of tasks were controlled, but the cyclists could choose rather freely when and where along the route to carry out the tasks, thus providing semi-naturalistic data on compensatory behaviour.The results show that the baseline and music conditions were similar in terms of visual behaviour. When interacting with the phone, it was found that glances towards the phone mostly came at the expense of glances towards traffic irrelevant gaze targets and also led to shortened glance durations to traffic relevant gaze targets, while maintaining the number of glances. This indicates that visual “spare capacity” is used for the execution of the telephone tasks. The task type influenced the overall task duration and the overall glance intensity towards the phone, but not the mean nor maximum duration of individual glances. Task pacing was the factor that influenced visual behaviour the most, with longer mean and maximum glance durations for self-paced tasks.In conclusion, the cyclists used visual strategies to integrate the handling of mobile phones into their cycling behaviour. Glances directed towards the phone did not lead to traffic relevant gaze targets being missed. In system-paced scenarios, the cyclists checked the traffic more frequently and intensively than in self-paced tasks. This leads to the assumption that cyclists prepare for self-initiated tasks by for example choosing a suitable location. Future research should investigate whether these strategies also exists amongst drivers and other road user groups.

Visual-auditory integration for visual search: a behavioral study in barn owls.

Barn owls are nocturnal predators that rely on both vision and hearing for survival. The optic tectum of barn owls, a midbrain structure involved in selective attention, has been used as a model for studying visual-auditory integration at the neuronal level. However, behavioral data on visual-auditory integration in barn owls are lacking. The goal of this study was to examine if the integration of visual and auditory signals contributes to the process of guiding attention toward salient stimuli. We attached miniature wireless video cameras on barn owls’ heads (OwlCam) to track their target of gaze. We first provide evidence that the area centralis (a retinal area with a maximal density of photoreceptors) is used as a functional fovea in barn owls. Thus, by mapping the projection of the area centralis on the OwlCam’s video frame, it is possible to extract the target of gaze. For the experiment, owls were positioned on a high perch and four food items were scattered in a large arena on the floor. In addition, a hidden loudspeaker was positioned in the arena. The positions of the food items and speaker were changed every session. Video sequences from the OwlCam were saved for offline analysis while the owls spontaneously scanned the room and the food items with abrupt gaze shifts (head saccades). From time to time during the experiment, a brief sound was emitted from the speaker. The fixation points immediately following the sounds were extracted and the distances between the gaze position and the nearest items and loudspeaker were measured. The head saccades were rarely toward the location of the sound source but to salient visual features in the room, such as the door knob or the food items. However, among the food items, the one closest to the loudspeaker had the highest probability of attracting a gaze shift. This result supports the notion that auditory signals are integrated with visual information for the selection of the next visual search target.

Analysis of Drivers’ Eye-Movement Characteristics When Driving around Curves

To investigate drivers’ visual strategies and the distribution of fixation points, much work had been done and salient conclusions had been drawn. However, there is still no consensus on what the gaze target is and what functional significance the point might have. To improve theories on this subject, research was done to investigate drivers’ visual characteristics. On-road experiment was carried out, and drivers’ eye-movement and vehicle driving parameters were registered when driving around left- and right-hand curves. The results showed that drivers’ gaze direction fluctuates around the reference axis, and the fixation points are distributed in the region centered on the horizontal gaze position rather than a particular point that has geographical meanings. With the consideration of the traffic rules in China, we suggest here that there is no particular point on which drivers concentrate. Any point or position that could indicate the bend’s curvature could be the so-called target point. Drivers just want to operate their vehicle so as to pass through bends safely in a comfortable and labor-saving way.

Fixation Duration Changes in Rett Syndrome after Habilitation Intervention

The purpose of the present study was to examine the effect of longitudinal habilitation intervention by care staff upon fixation duration in an individual with Rett syndrome using an eye-tracking system. The participant was a 22- year-old woman suffering from Rett syndrome. She could watch television but could not communicate verbally or execute purposeful upper extremity movements. We evaluated whether she could change the pattern of an eye gaze target by learning with the intervention of care staff. Fixation duration to the experimental targets was significantly changed after intervention for 3 weeks compared with before intervention. We consider that this improvement occurred because the patient learned the experimental tasks. Our findings suggest that individuals with Rett syndrome can acquire various abilities using eye gaze. Eye-tracking was shown to be a feasible method for visualizing the learning abilities of individuals with Rett syndrome and judging the outcome of habilitation intervention.

Combining dynamic head pose–gaze mapping with the robot conversational state for attention recognition in human–robot interactions

The ability to recognize the visual focus of attention (VFOA, i.e. what or whom a person is looking at) of people is important for robots or conversational agents interacting with multiple people, since it plays a key role in turn-taking, engagement or intention monitoring. As eye gaze estimation is often impossible to achieve, most systems currently rely on head pose as an approximation, creating ambiguities since the same head pose can be used to look at different VFOA targets. To address this challenge, we propose a dynamic Bayesian model for the VFOA recognition from head pose, where we make two main contributions. First, taking inspiration from behavioral models describing the relationships between the body, head and gaze orientations involved in gaze shifts, we propose novel gaze models that dynamically and more accurately predict the expected head orientation used for looking in a given gaze target direction. This is a neglected aspect of previous works but essential for recognition. Secondly, we propose to exploit the robot conversational state (when he speaks, objects to which he refers) as context to set appropriate priors on candidate VFOA targets and reduce the inherent VFOA ambiguities. Experiments on a public dataset where the humanoid robot NAO plays the role of an art guide and quiz master demonstrate the benefit of the two contributions.

What are you looking at?: The acuity of joint attention

How accurately can you determine what another person is looking at? This ability is essential for joint attention, a core, early-developing form of social interaction. While it has been shown that people can accurately determine whether another person is looking directly at them versus away, little is known about our ability to determine where another person is looking when their gaze is directed away from us. We measured subject's accuracy in 'reading" another person's gaze in a study that met three criteria: (1) subjects viewed another person's natural looking behavior live while that person (the "Actor") gazed at experimenter-indicated objects (2) without any constraint on head and eye movements and (3) in a crowded display containing many objects. We used a Kinect sensor to capture Actors' head movements for modeling the target's gaze behavior. In our "what-are-you-looking-at" task, the Actor gazes at one of 52 objects arrayed on a table in an arc around the Actor. In each trial, the Actor gazes at a different object for 9s. Our participants seated on the opposite side of the table to decide which target the Actor is looking at. Objects are spaced 10° apart in the Actor's visual angle. Our results indicate that: (1) Participant's accuracy of choosing the exactly correct object is about 40%, suggesting a limit on the acuity of joint attention; (2) Observers' incorrect responses are not random, but are systemically biased toward certain regions of the actor's visual field; (3) Individual observers differ reliably from each other in their accuracy, which ranges from 20%~60%; (4) The difference in readability of each Actor's gaze can be largely explained by the variance of the head movements recorded by the Kinect sensor. These results collectively reveal the acuity of joint attention by showing its limit, bias and variance. Meeting abstract presented at VSS 2014