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Face-to-face communication is one of the most natural forms of interaction between humans. Speech perception is an important part of this interaction. While speech could be said to be primarily auditory in nature, visual information can play a significant role in influencing perception. It is not well understood what visual information is important or how that information is collected. Previous studies have documented the preference to gaze at the eyes, nose, and mouth of the talking face, but physical saliency, i.e., the unique low-level features of the stimulus, has not been explicitly examined. Two eye-tracking experiments are presented to investigate the role of physical saliency in the guidance of gaze fixations during audiovisual speech perception. Experiment 1 quantified the physical saliency of a talking face and examined its relationship with the gaze behaviour of participants performing an audiovisual speech perception task and an emotion judgment task. The majority of fixations were made to locations on the face that exhibited high relative saliency, but not necessarily the maximally salient location. The addition of acoustic background noise resulted in a change in gaze behaviour and a decrease in correspondence between saliency and gaze behaviour, whereas changing the task did not alter this correspondence despite changes in gaze behaviour. Experiment 2 manipulated the visual information available to the viewer by using animated full-feature and point-light talking faces. Removing static information, such as colour, intensity, and orientation, from the stimuli elicited both a change in gaze behaviour and a decrease in correspondence between saliency and gaze behaviour. Removing dynamic information, particularly head motion, resulted in a decrease in correspondence between saliency and gaze behaviour without any change in gaze behaviour. The results of these experiments show that, while physical saliency is correlated with gaze behaviour, it cannot be the single factor determining the selection of gaze fixations. Interactions within and between bottom-up and top-down processing are suggested to guide the selection of gaze fixations during audiovisual speech perception. / Thesis (Master, Neuroscience Studies) -- Queen's University, 2008-12-18 13:10:01.694

Knowing where and when to look is critical for effective performance of visually guided tasks. A gaze strategy termed the quiet eye (QE; the final gaze before the onset of a critical movement) is strongly associated with motor skill proficiency, with earlier and longer QE periods leading to improved visuomotor control. Children with poor motor proficiency, such as those with Developmental Coordination Disorder (DCD), have impairments in the pick-up and processing of visual information, translating into poorly coordinated movements. The purpose of this project therefore was to perform the first examination of the QE strategy in children of different motor coordination abilities and furthermore to investigate the efficacy of task-specific QE training (QET) to improve the skills of children with and without DCD beyond the effects of a standard coaching technique. Study 1 determined that children with low motor coordination had later, shorter QE durations in comparison to coordinated children and as a result, performed worse in a specified motor task (throwing and catching). Study 2 therefore performed two experiments aimed at developing an appropriate but brief QET protocol for children to improve their throwing and catching ability. These experiments found that typically developing children were able to increase their QE durations with QET and this was reflected in a durable improvement in their motor skill execution. The final study examined this QET intervention in children with DCD. This was the first application of QET in a clinical population, and found that children with DCD were able to improve their QE durations, and make robust changes to their visuomotor control. These studies associate a longer QE with motor skill proficiency in children, and provide an important adjunct to current therapeutic intervention for children with poorly developed motor skills.

This thesis presents two studies that investigate how vision is used to control rapid, compensatory reach-to-grasp reactions. Compensatory grasping reactions were evoked in healthy young adults via unpredictable translations of large platforms on which the subjects stood or walked. The first study tracked natural gaze behaviour during responses to unexpected balance perturbations. It provided evidence that, unlike with voluntary movements, the eyes do not lead the hand during balance recovery – subjects relied on ‘stored’ information from central vision, continuously-available peripheral vision, or a combination of these sources to guide the hand. The second study investigated the efficacy of reliance on peripheral vision to guide rapid reach-to-grasp balance-recovery reactions. Peripheral vision was found to guide reach-to-grasp responses with sufficient accuracy to achieve a functional grasp of a relatively small handhold; however, peripherally-guided movements were slower when the handhold was in the extreme periphery.

This thesis presents two studies that investigate how vision is used to control rapid, compensatory reach-to-grasp reactions. Compensatory grasping reactions were evoked in healthy young adults via unpredictable translations of large platforms on which the subjects stood or walked. The first study tracked natural gaze behaviour during responses to unexpected balance perturbations. It provided evidence that, unlike with voluntary movements, the eyes do not lead the hand during balance recovery – subjects relied on ‘stored’ information from central vision, continuously-available peripheral vision, or a combination of these sources to guide the hand. The second study investigated the efficacy of reliance on peripheral vision to guide rapid reach-to-grasp balance-recovery reactions. Peripheral vision was found to guide reach-to-grasp responses with sufficient accuracy to achieve a functional grasp of a relatively small handhold; however, peripherally-guided movements were slower when the handhold was in the extreme periphery.

This document is intended to give an overview of the human subject study in a driving simulator that was conducted by the Chair of Traffic and Transportation Psychology (Verkehrspsychologie – VPSY) of the Technische Universität Dresden (TUD) to provide the Chair of Automotive Engineering (Lehrstuhl Kraftfahrzeugtechnik – LKT) of TUD with the necessary input for the validation of a stochastic traffic simulation, especially for the parameterization, consolidation, and validation of driver behaviour models. VPSY planned, conducted, and analysed a driving simulator study. The main purpose of the study was to analyse driving behaviour and gaze data at intersections in urban areas. Based on relevant literature, a simulated driving environment was created, in which a sample of drivers passed a variety of intersections. Considering different driver states, driving tasks, and traffic situations, the collected data provide detailed information about human gaze and driving behaviour when approaching and crossing intersections. The collected data was transferred to LKT for the development of the stochastic traffic simulation.

In Sweden almost three persons over the age of 65 years dies every daybecause of fall injuries. The overall societal costs of elderly fall accidentswere estimated to to be 14 billion SEK, and if no action is taken this cost isestimated to increase to 22 billion SEK until 2050. The individual decreasein life of quality due to pain, decrease of independence and, for those stillworking, a decrease in income is of course also well worth considering.It is well known that multitasking while walking will decrease attentionon the surroundings and gait behaviour which increases the risk of falling. Itis known that walking uses both sensory input and visual inputs to guide themotion. The visual input prepares the body to adjust itself before a step istaken to optimize the outcome.This study aimed to investigate the effect of multitasking on gaze strategiesand gait performance. Five healthy adults walked over a setup of ramps and astep while performing three different levels of cognitive loading: just walking,walking and performing mental arithmetic’s and walking and scrolling on amobile cell phone.The eye tracking device Pupil Core (Pupil Labs, Berlin, Germany) wasused to capture the gaze points of the participants and Vicon Nexus togetherwith force plates were used to capture data to compute the kinematics of theparticipants during the walking.The results revealed that four out of four participants had a lower ratio ofgaze fixations on objects of interest when scrolling on the phone comparedto just walking, and three out of four participants had a lower ratio of gazefixations on objects of interest when doing mental arithmetic’s compared tojust walking. Simultaneously the gait parameters and kinematics changed in away that might increase the risk of falling. Four out of four participants had adecrease in average stride length and average stride velocity when walkingwhile scrolling on a phone and a decrease in average stride velocity whenperforming mental arithmetic’s compared to just walking. Three out of fourparticipants had a decrease in average stride length when performing mentalarithmetic’s compared to just walking.Since the participant number was low more studies are needed to confirmthese results. The experimental design would benefit from adjustments to tryto separate the effect on gaze behaviour between altered cognitive loading andaltered gait pattern, but are a good base to use for further studies.

At least 2.6 billion people all over the world suffer from nearsightedness, among whom 312 million are under 19 years old. Just like other vision problems, uncorrected nearsightedness brings inconvenience to many human daily activities including walking. However, the influence of nearsightedness on gait patterns and gaze behaviours remains barely discovered. This project aimed to study the influence of nearsightedness on human visuomotor coordination in different environmental settings. An integrated system combining motion capture and eye-tracking was implemented for measuring gait and gaze simultaneously. Twelve participants were recruited to perform a protocol consisting of walking tasks in various visual and environmental conditions. Nine of the participants were eligible for data analysis. Gaze time distribution and gait cycle parameters were compared between participant groups (five with normal vision, four nearsighted), and among different walking tasks. Results revealed that comparing with the control group, the nearsighted participants made shorter and slower steps, as well as spent more time looking at the walking path. The walking path also affected the gait and gaze behaviours, with shorter step length and longer step time observed when the participants were walking uphill, while increased gaze attention was paid downhill. The practicality of combining gait analysis with eye-tracking was proved in this project, laying a foundation for future studies of visuomotor coordination.

Football penalty kicks are having increasing influence in today’s professional game. Despite this, little scientific evidence currently exists to ascertain the mechanisms behind performance failure in this task and/or the efficacy of training designed to improve penalty shooting. In a football penalty kick it has been reported that the majority of kickers do not look to the area they wish to place the ball; preferring to focus on the ‘keeper and predict anticipatory movements before shooting. Such a strategy seems counterproductive and contradictory to current research findings regarding visually guided aiming. Coordination of eye and limb movements has been shown to be essential for the production of accurate motor responses. A disruption to this coordination not only seems to negatively affect performance, but subsequent motor responses seem to follow direction of gaze. Thus, where the eyes lead actions tend to follow. In study 1, ten participants were asked to kick a standard sized football to alternate corners of a goal, whilst looking centrally and whilst looking where they intended to hit. This disruption of eye-limb coordination brought about a 15% reduction in kicking accuracy. When participants were asked to fixate centrally, their shots hit more centrally (17cm) than when they were allowed to look where they intended to hit. These results were in spite of no significant differences between the number of missed shots, preparation time and ball speed data across conditions. We concluded that centrally focused fixations dragged resultant motor actions inwards towards more central target locations. Put simply, where the eyes looked shots tended to follow. The second study sought to test the predictions of attentional control theory (ACT) in a sporting environment in order to establish how anxiety affects performance in penalty kicks. Fourteen experienced footballers took penalty kicks under low- and high-threat counterbalanced conditions while wearing a gaze registration system. Fixations to target locations (goalkeeper and goal area) were determined using frame-by-frame analysis. When anxious, footballers made faster first fixations and fixated for significantly longer toward the goalkeeper. This disruption in gaze behaviour brought about significant reductions in shooting accuracy, with shots becoming significantly centralized and within the goalkeeper’s reach. These findings support the predictions of ACT, as anxious participants were more likely to focus on the “threatening” goalkeeper, owing to an increased influence of the stimulus-driven attentional control system. A further prediction of ACT is that when anxious, performers are more likely to be distracted, particularly if the distracter is threat related. When facing penalty kicks in football (soccer), goalkeepers frequently incorporate strategies that are designed to distract the kicker. However, no direct empirical evidence exists to ascertain what effect such visual distractions have on the attentional control, and performance, of footballers. In the third study, eighteen experienced footballers took five penalty kicks under counterbalanced conditions of threat (low vs. high) and goalkeeper movement (stationary vs. waving arms) while wearing eye-tracking equipment. Results suggested that participants were more distracted by a moving goalkeeper than a stationary one and struggled to disengage from a moving goalkeeper under situations of high threat. Significantly more penalties were saved on trials when the goalkeeper was moving and shots were also generally hit closer to the goalkeeper (centrally) on these trials. The results provide partial support for the predictions of attentional control theory and implications for kickers and goalkeepers are discussed. The previous studies showed that anxiety can disrupt visual attention, visuomotor control and subsequent shot location in penalty kicks. However, optimal visual attention has been trained in other far aiming skills, improving performance and resistance to pressure. In study 4, we therefore asked a team of ten university soccer players to follow a quiet eye (QE; Vickers, 1996) training program, designed to align gaze with aiming intention to optimal scoring zones, over a seven week period. Performance and gaze parameters were compared to a placebo group (ten players) who received no instruction, but practiced the same number of penalty kicks over the same time frame. Results from a retention test indicated that the QE trained group had more effective visual attentional control; were significantly more accurate; and had 50% fewer shots saved by the goalkeeper than the placebo group. Both groups then competed in a penalty shootout to explore the influence of anxiety on attentional control and shooting accuracy. Under the pressure of the shootout the QE trained group failed to maintain their accuracy advantage, despite maintaining more distal aiming fixations of longer duration. The results therefore provide only partial support for the effectiveness of brief QE training interventions for experienced performers. This series of studies are the first to explore the gaze behaviour of football penalty takers in a quest to uncover and understand anxiety’s negative influence on attentional control and performance. They are also the first to explore the efficacy of goalkeeper distractions and training in improving performance from both the goalkeeper’s and kicker’s perspective. The results of these studies conclude that when anxious, penalty takers show an attentional bias toward the ‘threatening’ goalkeeper that can be increased and utilised by a goalkeeper employing distraction techniques and that penalty takers do benefit, to some extent, from a gaze-based pre-shot routine

Background Individuals with Autism Spectrum Disorder (ASD) have been reported to show socio-communicative impairments which are associated with impaired face perception and atypical gaze behaviour. Attending to faces and interpreting the important socio-communicative cues presented allows us to understand other’s cognitive states, emotions, wants and desires. This information enables successful social encounters and interactions to take place. Children with ASD not attending to these important social cues on the face may cause some of the socio-communicative impairments observed within this population. Examining how children with ASD attend to faces will enhance our understanding of their communicative impairments. Aim The present thesis therefore aimed to use eye-tracking methodology to examine attention allocation to faces for communicative cues in children with ASD. Method The first line of enquiry examined how children with ASD (n = 21; age = 13y7m) attended to faces presented within their picture communication systems compared to typically developing children matched on chronological age, verbal ability age and visuo-spatial ability age. The next investigation was conducted on the same group of children and examined how children with ASD attended to faces of different familiarity including, familiar, unfamiliar and the child’s own face. These faces were also presented with direct gaze or averted gaze to investigate how this would impact on the children’s allocation of attention. The final exploration highlighted how children with ASD (n = 20; age = 12y3m) attended to socially salient information (faces) and non-socially salient information (objects) presented within social scenes of varying complexity, compared to typically developing controls. Again groups were matched based on chronological age, verbal ability age, and visuo-spatial ability age. Results Children with ASD were shown to allocate attention to faces presented within their picture communication symbols similarly compared to their typically developing counterparts. All children were shown to fixate significantly longer on the face images compared to the object images. The children with ASD fixated for similar amounts of time to the eye and mouth regions regardless of familiarity and gaze direction compared to their controlled matches. All groups looked significantly longer at the eye areas compared to the mouth areas of the faces across all familiarity types. The children also fixated longer on the eye and mouth regions of direct gazing faces compared to the regions presented on the averted gazing faces. The children with ASD fixated on the faces and objects presented within social scenes similar to their typically developing counterparts across all complexity conditions. The children were shown to fixate significantly longer on the objects compared to the faces. Conclusions Children with ASD showed typical allocation of attention to faces. This suggests that faces are not aversive to them and they are able to attend to the relevant areas such as eye and mouth regions. This may have been influenced by the inclusion of high functioning children with ASD. However these results may also suggest that attention allocation and gaze behaviour are not the only factors which contribute to the socio-communicative impairments observed in ASD.