Line Of Gaze Research Articles

The Metamorphosis of an Oral Tradition: Dissonance in the Digital Stories of Aboriginal Peoples in Canada

Storytelling, as an oral tradition for Aboriginal peoples in Canada, is considered an ancient art form (Cruikshank 1990). Aboriginal peoples’ communities are often founded on stories that are characteristically sustaining: communicating the epistemologies and norms that constitute their worldviews (see Valdes 2004; Dei 2000). Digital storytelling is understood as a form of short narrative told in the first person and enhanced by visual text and symbolic imagery (Ohler 2005; Salpeter 2005; Weis et al. 2002). It is considered an extension of oral storytelling, is welcomed by Aboriginal peoples, and represents a “continuation of what Aboriginal people have been doing from time immemorial” (Hopkins 2006:342), and complements the preferred values and styles of interaction innate to Aboriginal pre-colonial education paradigms (Battiste 2000a and b; Barman et al. 1986). The metamorphosis of the oral tradition of storytelling into the digital medium creates a sense of audience for the elders who self-profess to be intermediaries from one generation to the next. As John Miles Foley (2008) insightfully suggests, oral tradition and digital technology are the frameworks to the fading era characteristic of the printed page. Digital storytelling situates the elders in the line of public gaze, where once their audience was more immediate and culturally relative. The presumed influence of their stories involves the variation of exposition, the representational language, and the latent relationships between the human and spiritual realms according to Aboriginal peoples’ worldviews. The elders’ role is to sustain the continuity of belief and so accept the digital as a means to reach a broader audience and illuminate a complex system of interrelated values. By employing a reflexive ethnographic framework to examine selected digital stories from the Omushkegowuk area in Ontario, Canada, a core interpretation of these worldviews emerged; namely, the presence and exploitation of western colonial influence has caused the profound dissonance experienced by Aboriginal peoples’ cultural, civil, symbolic, and spiritual paradigms, resulting from the presence and exploitation of western colonial influence. In turn,

The dependence of visual scanning performance on search direction and difficulty

Phillips and Edelman [Phillips, M. H., & Edelman, J. A. (2008). The dependence of visual scanning performance on saccade, fixation, and perceptual metrics. Vision Research, 48(7), 926–936] presented evidence that performance variability in a visual scanning task depends on oculomotor variables related to saccade amplitude rather than fixation duration, and that saccade-related metrics reflects perceptual span. Here, we extend these results by showing that even for extremely difficult searches trial-to-trial performance variability still depends on saccade-related metrics and not fixation duration. We also show that scanning speed is faster for horizontal than for vertical searches, and that these differences derive again from differences in saccade-based metrics and not from differences in fixation duration. We find perceptual span to be larger for horizontal than vertical searches, and approximately symmetric about the line of gaze.

Time course of selective attention in clinically depressed young adults: An eye tracking study

Depressed individuals display biased attention for emotional information when stimuli are presented for relatively “long” (e.g., 1 s) durations. The current study examined whether attentional biases are sustained over a much longer period. Specifically, clinically depressed and never depressed young adults simultaneously viewed images from four emotion categories (sad, threat, positive, neutral) for 30 s while line of visual gaze was assessed. Depressed individuals spent significantly more time viewing dysphoric images and less time viewing positive images than their never depressed counterparts. Time course analyses indicated that these biases were maintained over the course of the trial. Results suggest that depressed participants' attentional biases for dysphoric information are sustained for relatively long periods even when other emotional stimuli are present. Mood congruent information-processing biases appear to be a robust feature of depression and may have an important role in the maintenance of the disorder.

Von Pflugk (Dresden): Contribution to the Technique of Strabismus Operations, Suturing Anteriorly and Posteriorly

By a very simple calculation, one can find that a shift of the line of gaze of a normally built, emmetropic, hypermetropic, or weakly myopic eye by 5 degrees in the horizontal plane corresponds to ...

A longitudinal investigation of the still‐face effect at 6 months and joint attention at 12 months

An understanding of intentionality is thought to underlie developing joint attention. Similarly, early social‐communicative behaviours have been argued to reflect an appreciation of adult intentionality. This study explored the relation between social‐communicative behaviours during the still‐face effect at 6 months and joint attention at 12 months in a longitudinal sample of 42 infants. Three types of joint attention were investigated: coordinated joint attention (infant alternates looks between an adult and objects), initiating joint attention (infant uses communicative gestures to engage or direct adult attention) and attention following (infant follows an adult's line of gaze and pointing towards an object). The still‐face effect was correlated with later attention following, but not coordinated or initiating joint attention. Initiating joint attention was correlated with coordinated joint attention. We propose that the former association reflects a lower‐level detection of adult intentionality rather than a higher‐level interpretation of an agent's intentions towards outside entities. The findings support two bodies of research – one advocating for a distinction between types of joint attentional ability and a second proposing that infants can detect intentional actions without understanding or attributing mental states to objects.

Gaze and postural stability of elite ballet dancers, ACL-deficient and normal controls during the quiet stance and lunge

In two experiments we explore the relationship of gaze control to quiet stance and lunge in elite ballet dancers, ACL-deficient and normal controls. In order to maintain postural stability, all direct their gaze straight ahead at appropriate moments in order to maintain alignment of the centre of gravity over the functional centre of pressure (CoP). Not surprisingly, the elite ballet dancers were better at establishing a line of gaze forward at appropriate moments while the other groups were less likely to use this gaze control strategy. The ballet dancers appeared to use a visual straight ahead (VSA), which was a line of gaze horizontal to the base of support that momentarily stabilized their body for current and future actions. Surprisingly, they employed a more variable CoP, while the normal controls and ACL-deficient adopted a CoP distributed over a narrower and less dynamic base of support even while the gaze tracked a more variable pattern in space. In the lunge forward to return, the results were similar, with the exception the ballet dancers were more adept at returning their gaze to the VSA at appropriate moments while the ACL deficient had greater difficulty. These results are discussed within Bernstein’s notion of “freezing, freeing, and exploiting” the degrees of freedom of an action, in terms of both the control of the gaze and posture.

Ergonomics in Endoscopic Sinus Surgery: Systematic Review of the Literature

To conduct a systematic review of reports on the ergonomic posture of the surgeon during endoscopic sinus surgery. Literature review. Systematic review of the French- and English-language literature using PubMed from January 1970 to March 2004. Articles were divided into four categories: visualization through an endoscope or a videoendoscope, monitor position, sitting or standing position, and arm support. Endoscopic sinus surgery with direct vision through the endoscope is associated with faulty neck positioning and does not appear to bring any advantages in terms of surgical performance compared with vision via a video monitor. Low back pain and lower extremity complaints are commonly associated with the standing position. Spinal flexion seems more harmful than a straight posture. The preferred viewing angle for video monitors is a few degrees below the horizontal gaze line. An arm support can be beneficial because it is associated with minimization of neck, shoulder, and lumbar stress. We recommend (1) visualization via a television monitor instead of direct vision through an endoscope, (2) positioning the screen in direct axis with the surgeon's body and a few degrees below the horizontal line of gaze, (3) surgery in the seated position instead of the standing position, and (4) the use of an elbow support for the arm holding the endoscope.

Tracking the line of primary gaze in a walking simulator: Modeling and calibration

This article describes a system for tracking the line of primary gaze (LoPG) of participants as they view a large projection screen. Using a magnetic head tracker and a tracking algorithm, we find the onscreen location at which a participant is pointing a head-mounted crosshair. The algorithm presented for tracking the LoPG uses a polynomial function to correct for distortion in magnetic tracker readings, a geometric model for computing LoPG from corrected tracker measurements, and a method for finding the intersection of the LoPG with the screen. Calibration techniques for the above methods are presented. The results of two experiments validating the algorithm and calibration methods are also reported. Experiments showed an improvement in accuracy of LoPG tracking provided by each of the two presented calibration steps, yielding errors in LoPG measurements of less than 2 degrees over a wide range of head positions. Source code for the described algorithms can be downloaded from the Psychonomic Society Web archive, http://www.psychonomic.org/archive/.

Gaze control: role of the parietal cortex

Eye movements constitute one of the most basic means of interacting with our environment, allowing to orient to, localize and scrutinize the variety of potentially interesting objects that surround us. In this review we discuss the role of the parietal cortex in the control of saccadic and smooth pursuit eye movements, whose purpose is to rapidly displace the line of gaze and to maintain a moving object on the central retina, respectively. From single cell recording studies in monkey we know that distinct sub-regions of the parietal lobe are implicated in these two kinds of movement. The middle temporal (MT) and medial superior temporal (MST) areas show neuronal activities related to moving visual stimuli and to ocular pursuit. The lateral intraparietal (LIP) area exhibits visual and saccadic neuronal responses. Electrophysiology, which in essence is a correlation method, cannot entirely solve the question of the functional implication of these areas: are they primarily involved in sensory processing, in motor processing, or in some intermediate function? Lesion approaches (reversible or permanent) in the monkey can provide important information in this respect. Lesions of MT or MST produce deficits in the perception of visual motion, which would argue for their possible role in sensory guidance of ocular pursuit rather than in directing motor commands to the eye muscle. Lesions of LIP do not produce specific visual impairments and cause only subtle saccadic deficits. However, recent results have shown the presence of severe deficits in spatial attention tasks. LIP could thus be implicated in the selection of relevant objects in the visual scene and provide a signal for directing the eyes toward these objects. Functional imaging studies in humans confirm the role of the parietal cortex in pursuit, saccadic, and attentional networks, and show a high degree of overlap with monkey data. Parietal lobe lesions in humans also result in behavioral deficits very similar to those that are observed in the monkey. Altogether, these different sources of data consistently point to the involvement of the parietal cortex in the representation of space, at an intermediate stage between vision and action.

Forming Share Attention betwecn User and Robot Based on Face Posture Estimation

In human-robot interaction, the ability to detect and share user’s attention is the minimal requirement for an intelligent robot, since it is very important for robot to know human’s internal state. Here we present an algorithm, which is based on face posture estimation and the spatiotemporal image processing, to calculate a saliency map in order to form share attention. After the face posture estimation, we introduce an elliptic cone to approximate the user’s visual field, whose axis is fitted to the user’s gaze line that is not necessary to be detected beforehand. A visual acuity map on the user’s retina can be yielded according to the formulization of human’s visual acuity. We calculate the saliency map in terms of recency-weighted average of visual acuity maps along time axis so that the dynamic scene (for example, the case that user’s gaze line is shifting to a new object or the gazed object is moving) can affect the saliency map calculation, as well as the moving image areas are tracked to propagate the value of the visual acuity map from the current frame to the next one. Finally, we use the saliency map to form share attention in human-robot interaction, and it is also manifested that it will be possible to detect the user’s attention by only considering face orientation even when the eyes cannot be observed clearly.

Head posture and loading of the cervical spine

Calculations by Colombini et al. (Ergonomics of Working Postures. Taylor & Francis, London, 1985) showed that a line of gaze below the horizontal would load the cervical spine more than a horizontal gaze. Precision stadiometer tests were run, using seven subjects, to measure the effects on spinal length of different angles of gaze. After 1 h exposure whilst sitting in a controlled posture, there were significant differences in the shrinkage of the spine between the horizontal gaze and the 20° and 40° angles below the horizontal. The increased spinal loading demonstrated by the increase in spinal shrinkage calls into question the recommendations for angle of gaze recommended in textbooks.

Gaze pursuit and arm control of adolescent males diagnosed with attention deficit hyperactivity disorder (ADHD) and normal controls: evidence of a dissociation in processing visual information of short and long duration

Three-dimensional kinematic analysis of line of gaze, arm and ball was used to describe the visual and motor behaviour of male adolescents diagnosed with attention deficit hyperactivity disorder (ADHD). The ADHD participants were tested when both on (ADHD-On) and off (ADHD-Off) their medication and compared to age-matched normal controls in a modified table tennis task that required tracking the ball and hitting to cued right and left targets. Long-duration information was provided by a pre-cue, in which the target was illuminated approximately 2 s before the serve, and short-duration information by an early-cue illuminated about 350 ms after the serve, leaving ~500 ms to select the target and perform the action. The ADHD groups differed significantly from the control group in both the pre-cue and early-cue conditions in being less accurate, in having a later onset and duration of pursuit tracking, and a higher frequency of gaze on and off the ball. The use of medication significantly reduced the gaze frequency of the ADHD participants, but surprisingly this did not lead to an increase in pursuit tracking, suggesting a barrier was reached beyond which ball flight information could not be processed. The control and ADHD groups did not differ in arm movement onset, duration and velocity in the short-duration early-cue condition; in the long-duration pre-cue condition, however, the ADHD group's movement time onset and arm velocity differed significantly from controls. The results show that the ADHD groups were able to process short-duration information without experiencing adverse effects on their motor behaviour; however, long-duration information contributed to irregular movement control.

Neuroanatomical correlates of the near response: voluntary modulation of accommodation/vergence in the human visual system.

This study identifies brain regions participating in the execution of eye movements for voluntary positive accommodation (VPA) during open-loop vergence conditions. Neuronal activity was estimated by measurement of changes in regional cerebral blood flow (rCBF) with positron emission tomography and 15O-water. Thirteen naive volunteers viewed a checkerboard pattern with their dominant right eye, while a lens interrupted the line of gaze during alternate 1.5 s intervals. Three counterbalanced tasks required central fixation and viewing of a stationary checkerboard pattern: (i) through a 0.0 diopter (D) lens; (ii) through a -5.0-D lens while avoiding volitional accommodation and permitting blur; and (iii) through a -5. 0-D lens while maintaining maximal focus. The latter required large-amplitude, high-frequency VPA. As an additional control, seven of the subjects viewed passively a digitally blurred checkerboard through a 0.0-D lens as above. Optometric measurements confirmed normal visual acuity and ability to perform the focusing task (VPA). Large-amplitude saccadic eye movements, verified absent by electro-oculography, were inhibited by central fixation. Image averaging across subjects demonstrated multifocal changes in rCBF during VPA: striate and extrastriate visual cortices; superior temporal cortices; and cerebellar cortex and vermis. Decreases in rCBF occurred in the lateral intraparietal area, prefrontal and frontal and/or supplementary eye fields. Analysis of regions of interest in the visual cortex showed systematic and appropriate task dependence of rCBF. Activations may reflect sensorimotor processing along the reflex arc of the accommodation system, while deactivations may indicate inhibition of systems participating in visual search.

Investigation of the polarization optics of the living human cornea and lens with Purkinje images

We present what to our knowledge is a new method for assessing the polarization optics of the cornea and lens, by examining the state of polarization of the first, second, and fourth Purkinje images. When linearly polarized light is incident on the cornea at 70 degrees to the line of gaze along the horizontal meridian, and then traverses the cornea, or the cornea and the lens, the emergent light is elliptically polarized. The degree of ellipticity varies widely between subjects. The results indicate that both the cornea and the lens may be optically active and to our knowledge are the first to suggest that the cornea may exhibit circular birefringence.

Aiming Accuracy of the Line of Gaze and Redesign of the Gaze-Pointing System

The current experiment tested the aiming accuracy of the eye for targets at nine different positions and of two different sizes. The left eye was tracked to record the line of gaze with an infrared eye-monitoring device. For each subject, horizontal shift, vertical shift, standard deviations of the X and Y coordinates, and 95th percentile of the horizontal and vertical shifts from the nine target centers were calculated to indicate the precision, accuracy, and possible design limits of the gaze points. Analysis showed that the target's position had a strong effect on the vertical shift, standard deviations of the Y coordinate, and 95th percentile of the vertical shift. The effect of target size was not significant on any of the dependent measures. The research findings have important implications for the redesign of the gaze-pointing device. Visual targets appearing below the horizontal line of sight should be larger than those above. Based on the 95th percentile of the horizontal and vertical shifts, targets should be approximately 2.0 degrees wide and 2.4 degrees long above or coinciding with the horizontal line of gaze and 2.6 degrees wide and 3.9 degrees (cm) long below the horizontal line of gaze.

Testing the relative conspicuity of safety garments for New Zealand forestry workers

The relative conspicuities of six test garments (fluorescent orange, green/red, high-contrast, fluorescent lime-yellow, white, black) were assessed to guide the selection process of a standard upper body safety garment to be used within the New Zealand logging industry. Six male and four female participants, aged between 18 and 26 years, volunteered to perform 10 trials each on a demanding, central (tracking) task, while peripherally searching colour slides for test garments displayed on each of eight positions, against a pine forest background typically found in the New Zealand forestry. During each trial, transparency luminance was first gradually increased from darkness to daylight and then decreased to darkness again within 180 s. A head mounted ASL eye tracking system (4000SU) recorded the eye line of gaze for each participant, enabling a rank order of detection to be obtained for the tested garments in each trial. The fluorescent lime-yellow, fluorescent orange and white test garments were detected earlier than any other test garments across all trials, and the fluorescent lime-yellow test garment was detected first with a higher frequency than the white test garment. It was concluded that while white may be the most visible colour in near darkness conditions, as it provides highest contrast, fluorescent lime-yellow stands out better in twilight and daylight conditions against the pine forest background. The results of this study led to the promotion of fluorescent lime-yellow as the standard safety colour used in upper body garments within the New Zealand forest industry.

Layout Perception during Simulated Locomotion

Our purpose was to show how the modification of visual information available to moving observers can change the way they perceive their path and the structure of the environments they pass through. Stimulus trials simulated locomotion across a tree-filled plane while the gaze was directed at a particular tree. In the first experiment we varied the angle between the line of gaze and the simulated direction of movement (GMA) between 0° and 20°. In the second experiment we used either inward displacement (ID) of some objects (moving towards the fovea) or other flow patterns. After each trial, participants drew their path or the position of the particular tree on a schematic map of the environment. In the first experiment, with respect to the fixation point, as GMA increased so did the shift in the drawn paths, and we measured a significant correlation between the two. In the second, ID changed the accuracy of depth representation for the most distant objects in the visual field. In conclusion, the strong relation between GMA and the reproduced paths, even though they are discrepant from the true paths, suggests that the maintenance of course in the real world may not be based on a maplike mental representation of one's trajectory. In addition, opposite motions in the same region of the visual field (as encountered with ID patterns), may significantly modify the information used for integrating spatial relationships in the environment. The attractive power of these regions in gaze control may also renew our theoretical interest in selective attention.

Rotation of Listing's plane by horizontal, vertical and oblique prism-induced vergence

We examined the changes in Listing's plane resulting from prismatically induced vergence. The three-dimensional angular positions of the two eyes were compared in normal subjects wearing search coils and gazing at targets 1.9 m away with and without prisms. For horizontal base-out prisms each degree of convergence in one eye yielded 0.72 deg of temporal rotation of Listing's plane in that eye. The results from vertical prisms were not what was expected from the horizontal results. A base-up prism on the right eye induced a downward and temporal rotation of Listing's plane. A base-down prism on the right eye induced an upward and nasal rotation of Listing's plane. The effects of oblique prisms were those expected from combining the effects of horizontal and vertical prisms. Thus in addition to producing a horizontal or vertical misalignment of the gaze line, prisms induce an unexpected position-dependent torsional disparity.

Computer graphics eye‐animation and feeling of gaze line

AbstractIn a teleconferencing system with realistic sensations, human images are generated by computer graphics (CG). This requires animating natural eye movement with CG. This paper describes a real‐time animation technique to generate blinking and gaze shift, while still considering convergence using a graphic workstation. Moreover, the feeling of eye contract is evaluated using this animation. In this experiment, the gaze generated by CG using two‐dimensional (2‐D) or 3‐D display is evaluated subjectively and compared with the gaze of an actual person. Also, an experiment is performed on the time required for perception of eye contact when the eyes of the CG image are moving. Then, a real‐time CG eyeanimation system combined with an eye‐movement detector is described. Also, the allowable transmission delay time when using this system is evaluated subjectively.

Effects of Full-Field Visual Input on the Three-Dimensional Properties of the Human Vestibuloocular Reflex1

The three-dimensional (3-D) properties of the vestibuloocular reflex (VOR) were studied in six normal human subjects during passive whole-body rotations in darkness and with full-field visual input in light. Subjects were asked to fixate a point target stationary in space straight ahead or to imagine such a target in darkness. Using a 3-D rotating chair, subjects were rotated sinusoidally (frequency .3 Hz, maximum speed 37.5°/s) about an earth-vertical axis for horizontal stimulation and about an earth-horizontal axis for vertical and torsional stimulation. The subject faced forward for vertical stimulation, 90° to the side for torsional stimulation, or 15° to the right or left side for combined vertical and torsional stimulation. Left eye position was measured using 3-D search coils. The VOR response was quantified using the 3-D analogue of gain, a 3 × 3 matrix where each element describes the dependence of one component – torsional, vertical, or horizontal – of eye velocity on one component of head velocity. Average gain matrices were calculated for three cycles of rotation (10 s). Major findings were: (1) Gain values for the VOR were higher in light than in darkness for all directions. In light, vertical and horizontal responses were fully compensatory in both magnitude and direction, whereas the torsional responses were still weak. (2) Intersubject variability, large in the dark, was very small in the light for the vertical and horizontal responses but still considerable for the torsional. (3) Crosscoupling, in the form of partially horizontal eye movements in response to a torsional head rotation, was present in darkness but disappeared in light. (4) The VOR showed the same eye position dependence in darkness and in light; that is, if the eye is looking x° away from straight ahead, the eye rotation axis in response to a horizontal or vertical head rotation tilts about x°/4 in the same direction as the gaze line. These axis tilts are incompatible with perfect stabilization of the retinal image, but they are qualitatively appropriate for preserving Listing’s law.