The influence of oblique viewing on axial and peripheral refraction for emmetropes and myopes

Refraction may be affected by the forces of lids and extraocular muscles when eye direction and head direction are not aligned (oblique viewing) which might potentially influence past findings on peripheral refraction of the eye. We investigated the effect of oblique viewing on axial and peripheral refraction. In a first experiment, cycloplegic axial refractions were determined when subjects' heads were positioned to look straight-ahead through an open-view autorefractor and when the heads were rotated to the right or left by 30° with compensatory eye rotation (oblique viewing). Subjects were 16 young emmetropes (18–35 years), 22 young myopes (19–36 years) and 15 old emmetropes (45–60 years). In a second experiment, cycloplegic peripheral refraction measurements were taken out to ±34° horizontally from fixation while the subjects rotated their heads to match the peripheral refraction angles (eye in primary position with respect to the head) or the eyes were rotated with respect to the head (oblique viewing). Subjects were 10 emmetropes and 10 myopes. We did not find any significant changes in axial or peripheral refraction upon oblique viewing for any of the subject groups. In general for the range of horizontal angles used, it is not critical whether or not the eye is rotated with respect to the head during axial or peripheral refraction.

Axial length changes with shifts of gaze direction in myopes and emmetropes

Purpose. The purpose of the study was to investigate the changes in axial length occurring with shifts in gaze direction. Methods. Axial length measurements were obtained from the left eye of 30 young adults (10 emmetropes, 10 low myopes, and 10 moderate myopes) through a rotating prism with 15° deviation, along the foveal axis, using a noncontact optical biometer in each of the nine different cardinal directions of gaze over 5 minutes. The subject's fellow eye fixated on an external distance (6 m) target to control accommodation, also with 15° deviation. Axial length measurements were also performed in 15° and 25° downward gaze with the biometer inclined on a tilting table, allowing gaze shifts to be achieved with either full head turn but no eye turn, or full eye turn with no head turn. Results. There was a significant influence of gaze angle and time on axial length (both P < 0.001), with the greatest axial elongation (+18 ± 8 μm) occurring with inferonasal gaze (P < 0.001) and a slight decrease in axial length in superior gaze (−12 ± 17 μm) compared with primary gaze (P < 0.001). In downward gaze, a significant axial elongation occurred when eye turn was used (P < 0.001), but not when head turn was used to shift gaze (P > 0.05). Conclusions. The angle of gaze has a small but significant short-term effect on axial length, with greatest elongation occurring in inferonasal gaze. The elongation of the eye appears to be due to the influence of the extraocular muscles, in particular the oblique muscles.

Optical and biomechanical factors, associated with near work and myopia

Near work may play an important role in the development of myopia in the younger population. The prevalence of myopia has also been found to be higher in occupations that involve substantial near work tasks, for example in microscopists and textile workers. When nearwork is performed, it typically involves accommodation, convergence and downward gaze. A number of previous studies have examined the effects of accommodation and convergence on changes in the optics and biometrics of the eye in primary gaze. However, little is known about the influence of accommodation on the eye in downward gaze. This thesis is primarily concerned with investigating the changes in the eye during near work in downward gaze under natural viewing conditions. To measure wavefront aberrations in downward gaze under natural viewing conditions, we modified a commercial Shack-Hartmann wavefront sensor by adding a relay lens system to allow on-axis ocular aberration measurements in primary gaze and downward gaze, with binocular fixation. Measurements with the modified wavefront sensor in primary and downward gaze were validated against a conventional aberrometer using both a model eye and in 9 human subjects. We then conducted an experiment to investigate changes in ocular aberrations associated with accommodation in downward gaze over 10 mins in groups of both myopes (n = 14) and emmetropes (n =12) using the modified Shack-Hartmann wavefront sensor. During the distance accommodation task, small but significant changes in refractive power (myopic shift) and higher order aberrations were observed in downward gaze compared to primary gaze. Accommodation caused greater changes in higher order aberrations (in particular coma and spherical aberration) in downward gaze than primary gaze, and there was evidence that the changes in certain aberrations with accommodation over time were different in downward gaze compared to primary gaze. There were no obvious systematic differences in higher order aberrations between refractive error groups during accommodation or downward gaze for fixed pupils. However, myopes exhibited a significantly greater change in higher order aberrations (in particular spherical aberration) than emmetropes for natural pupils after 10 mins of a near task (5 D accommodation) in downward gaze. These findings indicated that ocular aberrations change from primary to downward gaze, particularly with accommodation. To understand the mechanism underlying these changes in greater detail, we then extended this work to examine the characteristics of the corneal optics, internal optics, anterior biometrics and axial length of the eye during a near task, in downward gaze, over 10 mins. Twenty young adult subjects (10 emmetropes and 10 myopes) participated in this study. To measure corneal topography and ocular biometrics in downward gaze, a rotating Scheimpflug camera and an optical biometer were inclined on a custom built, height and tilt adjustable table. We found that both corneal optics and internal optics change with downward gaze, resulting in a myopic shift (~0.10 D) in the spherical power of the eye. The changes in corneal optics appear to be due to eyelid pressure on the anterior surface of the cornea, whereas the changes in the internal optics (an increase in axial length and a decrease in anterior chamber depth) may be associated with movement of the crystalline lens, under the action of gravity, and the influence of altered biomechanical forces from the extraocular muscles on the globe with downward gaze. Changes in axial length with accommodation were significantly greater in downward gaze than primary gaze (p < 0.05), indicating an increased effect of the mechanical forces from the ciliary muscle and extraocular muscles. A subsequent study was conducted to investigate the changes in anterior biometrics, axial length and choroidal thickness in nine cardinal gaze directions under the actions of the extraocular muscles. Ocular biometry measurements were obtained from 30 young adults (10 emmetropes, 10 low myopes and 10 moderate myopes) through a rotating prism with 15° deviation, along the foveal axis, using a non-contact optical biometer in each of nine different cardinal directions of gaze, over 5 mins. There was a significant influence of gaze angle and time on axial length (both p < 0.001), with the greatest axial elongation (+18 ± 8 μm) occurring with infero-nasal gaze (p < 0.001) and a slight decrease in axial length in superior gaze (−12 ± 17 μm) compared with primary gaze (p < 0.001). There was a significant correlation between refractive error (spherical equivalent refraction) and the mean change in axial length in the infero-nasal gaze direction (Pearson's R2 = 0.71, p < 0.001). To further investigate the relative effect of gravity and extraocular muscle force on the axial length, we measured axial length in 15° and 25° downward gaze with the biometer inclined on a tilting table that allowed gaze shifts to occur with either full head turn but no eye turn (reflects the effect of gravity), or full eye turn with no head turn (reflects the effect of extraocular muscle forces). We observed a significant axial elongation in 15° and 25° downward gaze in the full eye turn condition. However, axial length did not change significantly in downward gaze over 5 mins (p > 0.05) in the full head turn condition. The elongation of the axial length in downward gaze appears to be due to the influence of the extraocular muscles, since the effect was not present when head turn was used instead of eye turn. The findings of these experiments collectively show the dynamic characteristics of the optics and biometrics of the eye in downward gaze during a near task, over time. These were small but significant differences between myopic and emmetropic eyes in both the optical and biomechanical changes associated with shifts of gaze direction. These differences between myopes and emmetropes could arise as a consequence of excessive eye growth associated with myopia. However the potentially additive effects of repeated or long lasting near work activities employing infero-nasal gaze could also act to promote elongation of the eye due to optical and/or biomechanical stimuli.

Eye Gaze and Turn Taking in Aphasia Patients

In every conversation you have, there is an unspoken code – a set of social rules that guide you. When to stop talking, where to look, when to listen and when to talk…

Eye Gaze Behavior at Turn Transition: How Aphasic Patients Process Speakers' Turns during Video Observation

The human turn-taking system regulates the smooth and precise exchange of speaking turns during face-to-face interaction. Recent studies investigated the processing of ongoing turns during conversation by measuring the eye movements of noninvolved observers. The findings suggest that humans shift their gaze in anticipation to the next speaker before the start of the next turn. Moreover, there is evidence that the ability to timely detect turn transitions mainly relies on the lexico-syntactic content provided by the conversation. Consequently, patients with aphasia, who often experience deficits in both semantic and syntactic processing, might encounter difficulties to detect and timely shift their gaze at turn transitions. To test this assumption, we presented video vignettes of natural conversations to aphasic patients and healthy controls, while their eye movements were measured. The frequency and latency of event-related gaze shifts, with respect to the end of the current turn in the videos, were compared between the two groups. Our results suggest that, compared with healthy controls, aphasic patients have a reduced probability to shift their gaze at turn transitions but do not show significantly increased gaze shift latencies. In healthy controls, but not in aphasic patients, the probability to shift the gaze at turn transition was increased when the video content of the current turn had a higher lexico-syntactic complexity. Furthermore, the results from voxel-based lesion symptom mapping indicate that the association between lexico-syntactic complexity and gaze shift latency in aphasic patients is predicted by brain lesions located in the posterior branch of the left arcuate fasciculus. Higher lexico-syntactic processing demands seem to lead to a reduced gaze shift probability in aphasic patients. This finding may represent missed opportunities for patients to place their contributions during everyday conversation.

Correlating eye gaze direction, depth and vehicle information on an interactive map for driver training

The over represented number of novice drivers involved in crashes is alarming. Driver training is one of the interventions aimed at mitigating the number of crashes that involve young drivers. Experienced drivers have better hazard perception ability compared to inexperienced drivers. Eye gaze patterns have been found to be an indicator of the driver's competency level. The aim of this paper is to develop an in-vehicle system which correlates information about the driver's gaze and vehicle dynamics, which is then used to assist driver trainers in assessing driving competency. This system allows visualization of the complete driving manoeuvre data on interactive maps. It uses an eye tracker and perspective projection algorithms to compute the depth of gaze and plots it on Google maps. This interactive map also features the trajectory of the vehicle and turn indicator usage. This system allows efficient and user friendly analysis of the driving task. It can be used by driver trainers and trainees to understand objectively the risks encountered during driving manoeuvres. This paper presents a prototype that plots the driver's eye gaze depth and direction on an interactive map along with the vehicle dynamics information. This prototype will be used in future to study the difference in gaze patterns in novice and experienced drivers prior to a certain manoeuvre.

Publishing, postage, and prizes : classic Australian children’s literature in the public eye

2012 saw the publication of competing and complementary lines of Australian “classics”: “A&R Australian Classics” (HarperCollins) and “Text Classics” (Text Publishing). While Angus and Robertson were key in establishing a canon of Australian children’s classics in the twentieth century, it was the Text Classics line which included a selection of young people’s titles in their 2013. In turn, Penguin Australia launched a selection of “Australian Children’s Classics”. In so doing, these publishers were drawing on particular literary and visual cultural traditions in Australian children’s literature. Public assertions of a particular selection of children’s books reveals not only contemporary assumptions about desirable childhood experiences but about the operation of nostalgia therein. In encouraging Australian adults to judge books by their covers, such gestures imply that Australian children may be similarly understood. Importantly, the illusion of unity, sameness, and legibility which is promised by circumscribed canons of “classic” children’s literature may well imply a desire for similarly illusory, unified, legible, “classic” childhood. This paper attends to public attempts to materialise (and legitimise) a canon of classic Australian children’s literature. In particular, it considers the ways in which publishing, postage stamps, and book awards make visible a range of children’s books, but do so in order to either fix or efface the content or meaning of the books themselves. Moving between assertions of the best books for children from the 1980s to today, and of the social values circulated within those books, this paper considers the possibilities and problematics of an Australian children’s canon.

Keep an "eye" on the text: The Use of Self-mention in the Academic Writing of Experts

One of the most controversial inquiries in academic writing is whether it is admissible to use first person pronouns in a scientific paper or not. Many professors discourage their students from using them, rather favoring a more passive tone, and thus causing novices to avoid inserting themselves into their texts in an expert-like manner. Abundant research, however, has recently attested that negotiation of identity is plausible in academic prose, and there is no need for a paper to be void of an authorial identity. Because in the course of the English Studies Degree we have received opposing prompts in the use of I, the aim of this dissertation is to throw some light upon this vexed issue. To this end, I compiled a corpus of 16 Research Articles (RAs) that comprises two sub-corpora, one featuring Linguistics RAs and the other one Literature RAs, and each, in turn, consists of articles written by American and British authors. I then searched for real occurrences of I, me, my, mine, we, us, our and ours, and studied their frequency, rhetorical functions and distribution along each paper. The results obtained certainly show that academic writing is no longer the faceless prose that it used to be, for I is highly used in both disciplines and varieties of English. Concerning functions, the most typically used roles were the use of I to take credit for the writer’s research process, and also those involving plural forms. With respect to the spatial disposition, all sections welcomed first person pronouns, but the Method and the Results/Discussion sections seem to stimulate their appearance. On the basis of these findings, I suggest that an L2 writing pedagogy that is mindful not only of the language proficiency, but also of the students’ own identity may have a beneficial effect on the composition of their texts.

"Judicial Activism in the ""Eye of the Beholder"" : the Israeli High Court of Justice and the Human Rights of the Palestinians in the Occupied Territories"

Il est mondialement reconnu que les institutions judiciaires jouent un rôle central dans le processus de prise de décisions politiques, à la fois au niveau national et international. C’est d’ailleurs le cas à la Haute Cour de justice d’Israël. L’étendue de son succès (ou de son échec) dans la tentative de trouver une solution aux violations des droits humains dans les territoires occupés est un problème qui continue de faire l’objet de bien des débats et de recherches académiques. À cet égard, il a été suggéré que, malgré l’absence de constitution écrite et l’existence d’un état d’urgence prolongé en Israël, la Haute Cour de justice a réussi à adopter une approche « judiciairement active » quant à la protection et la promotion des droits de l’homme de manière générale, y compris ceux des Palestiniens dans les territoires occupés. Dans cette perspective, le débat sur le processus d’examen judiciaire de la Haute Cour de Justice tient pour acquise la notion qu’Israël est une démocratie. Ainsi, cet article cherche à examiner cette hypothèse. Premièrement, en adoptant la position que le processus de révision judiciaire est compatible avec la démocratie et la règle de loi. Deuxièmement, il examine l’approche « judiciairement active » de la Cour et soumet un bref aperçu du processus, des outils et des principes légaux que la Cour adopte pour examiner les actions des autorités israéliennes, y compris l’armée, et imposer une loi commune de protection des droits de la personne, donc ceux des Palestiniens dans les territoires occupés. L’article argumente également que le contrôle prolongé des territoires occupés par Israël a eu des conséquences significatives, car tout effort fourni par la Cour pour garantir le respect des droits humains de la population civile palestinienne doit se faire sans compromettre la sécurité du pouvoir israélien. La conclusion à laquelle on arrive ici dépend de la façon dont on qualifie ce contrôle: une occupation à long terme ou une annexion (ce qui n’est pas réglementaire par rapport à loi internationale), ce qui n’est pas sans conséquence sur le rôle que la Haute Cour de justice peut effectivement jouer pour faire respecter les droits de la personne dans les territoires occupés.

Evaluation of Binocular Eye Trackers and Algorithms for 3D Gaze Interaction in Virtual Reality Environments

Tracking user’s visual attention is a fundamental aspect in novel human-computer interaction paradigms found in Virtual Reality. For example, multimodal interfaces or dialogue-based communications with virtual and real agents greatly benefit from the analysis of the user’s visual attention as a vital source for deictic references or turn-taking signals. Current approaches to determine visual attention rely primarily on monocular eye trackers. Hence they are restricted to the interpretation of two-dimensional fixations relative to a defined area of projection. The study presented in this article compares precision, accuracy and application performance of two binocular eye tracking devices. Two algorithms are compared which derive depth information as required for visual attention-based 3D interfaces. This information is further applied to an improved VR selection task in which a binocular eye tracker and an adaptive neural network algorithm is used during the disambiguation of partly occluded objects.

Street crossing behavior in younger and older pedestrians: an eye- and head-tracking study

BACKGROUND: Crossing a street can be a very difficult task for older pedestrians. With increased age and potential cognitive decline, older people take the decision to cross a street primarily based on vehicles' distance, and not on their speed. Furthermore, older pedestrians tend to overestimate their own walking speed, and could not adapt it according to the traffic conditions. Pedestrians' behavior is often tested using virtual reality. Virtual reality presents the advantage of being safe, cost-effective, and allows using standardized test conditions. METHODS: This paper describes an observational study with older and younger adults. Street crossing behavior was investigated in 18 healthy, younger and 18 older subjects by using a virtual reality setting. The aim of the study was to measure behavioral data (such as eye and head movements) and to assess how the two age groups differ in terms of number of safe street crossings, virtual crashes, and missed street crossing opportunities. Street crossing behavior, eye and head movements, in older and younger subjects, were compared with non-parametric tests. RESULTS: The results showed that younger pedestrians behaved in a more secure manner while crossing a street, as compared to older people. The eye and head movements analysis revealed that older people looked more at the ground and less at the other side of the street to cross. CONCLUSIONS: The less secure behavior in street crossing found in older pedestrians could be explained by their reduced cognitive and visual abilities, which, in turn, resulted in difficulties in the decision-making process, especially under time pressure. Decisions to cross a street are based on the distance of the oncoming cars, rather than their speed, for both groups. Older pedestrians look more at their feet, probably because of their need of more time to plan precise stepping movement and, in turn, pay less attention to the traffic. This might help to set up guidelines for improving senior pedestrians' safety, in terms of speed limits, road design, and mixed physical-cognitive trainings.

Changing the servicescape : The influence of music, self-disclosure and eye gaze on service encounter experience and approach-avoidance behavior

The purpose of this thesis is to investigate and understand the effect of a servicescape’s ambient and social conditions on consumers’ service encounter experience and their approach/avoidance behavior in a retail context. In three papers, with a total sample of over 1600 participants (including 550 actual consumers) and seven experiments, the author investigates the effect of music (ambient stimuli), employees’ self-disclosure (verbal social stimuli) and employees’ gazing behavior (nonverbal social stimuli) on consumers’ service encounter experience and approach/avoidance behavior in a retail store. Paper I comprised two experiments, and the aim was to investigate the influence of music on emotions, approach/avoidance behavior. Paper II comprised two experiments, and the aim was to investigate the effect of frontline employees’ personal self-disclosure on consumers’ reciprocal behavior. Paper III comprised three experiments, and the aim was to investigate the influence of employee’s direct eye gaze/ averted eye gaze on consumer emotions, social impression of the frontline employee and encounter satisfaction in different purchase situations. The results in this thesis show that music affects consumers in both positive and negative ways (Paper I). Self-disclosure affects consumers negatively, in such a way that it decreases encounter satisfaction  (Paper II) and, finally, eye gaze affects consumers by regulating both positively – and in some cases also negatively – consumers’ social impression of the frontline employee and their encounter satisfaction (Paper III). The conclusions of this thesis are that both ambient and social stimuli in a servicescape affect consumers’ internal responses, which in turn affect their behavior. Depending on the purchase situation, type of retail, and stimuli, the internal and behavioral responses are different.