Title Promoter Affiliations Abstract "Eye movement and cognitive-interactional linguistics. In a multimodal approach to interaction management." "Kurt Feyaerts" "Multimodality, Interaction and Discourse, Kulak Kortrijk Campus, Multimodality, Interaction and Discourse, Leuven" "Face-to-face communication is an inherently multimodal process, with multiple semiotic channels operating simultaneously and collaboratively, including verbal, para-verbal (e.g. intonation, pace and volume of speech) and non-verbal behaviour (e.g. gaze, gesture, posture). This project presents a novel approach to multimodal interaction, with a specific focus on the role of interlocutors’ eye gaze in relation to the other semiotic channels. In order to capture the continuous stream of visible information being exchanged in dialogue, we use a recently developed paradigm of multifocal eyetracking, with mobile eye-trackers simultaneously recording the gaze behaviour of two or more conversation partners in a face-to-face setting. The recordings of two- and three-party interactions will be used to explore the multimodal dynamics of interaction management, and more specifically the negotiation of speakership (turn allocation and turn-taking) and the signalling of attention and understanding (grounding). The analysis of these phenomena focuses both on the temporal dynamics, or how they are organized sequentially in the unfolding interactions, and on the emergence of multimodal patterns across semiotic channels (multimodal information packages, McNeill 2006). The results of the analyses may challenge key concepts in cognitive(-interactional) linguistics, conversation analysis and psycholinguistics." "Instrumented dystonia and choreoathetosis assessment protocol (IDCA) of upper limb movements in cerebral palsy" "Elegast Monbaliu" "Rehabilitation Sciences, Bruges Campus, Research Group for Neurorehabilitation (eNRGy)" "The general aim of this doctoral project was to increase our insights into the qualitative and quantitative assessment methods for childhood-onset dystonia and choreoathetosis. Dystonia and choreoathetosis are movement disorders that interfere with activities of daily living and have a tremendous impact on quality of life. Dystonia and choreoathetosis can occur in children after a brain lesion near birth, as a consequence of a genetic defect, or without known origin, but its assessment is complicated due to the multi-faceted presentation of both movement disorders, especially if they present concurrently. For the qualitative part of this project, we focused on the assessment of dystonia and choreoathetosis using the dyskinesia impairment scale (DIS). This scale was specifically developed to assess dystonia and choreoathetosis in individuals with dyskinetic cerebral palsy. We expanded our focus towards individuals with inherited or idiopathic dystonias, since there is currently no assessment tool available that evaluates both individuals with primary and secondary dystonia. For the quantitative part of this project, we focused on upper limb movements, since many individuals with dyskinetic cerebral palsy can perform simple upper limb tasks. We implemented an instrumented assessment protocol using different methodologies during functional upper limb tasks in individuals with dyskinetic cerebral palsy.In chapter one, we explored the reliability and validity of the DIS in individuals with inherited and/or idiopathic dystonia to evaluate whether the DIS can be used to asses presence and severity of dystonia and choreoathetosis in this group. We found excellent inter-rater reliability for the total DIS scores and the dystonia subscale amongst three raters, indicating that presence and severity of dystonia can be reliably assessed in individuals with inherited or idiopathic dystonia. Inter-rater reliability for the presence and severity of choreoathetosis was somewhat lower, but still good. The lower inter-rater reliability for choreoathetosis could be attributed to lower presence of choreoathetosis in our study sample, and thus a higher presence of ‘zeros’, signifying absence of choreoathetosis. All scores showed high test-retest reliability, indicating that the DIS is a reliable scale to assess presence and severity of dystonia and/or choreoathetosis over time in a study sample with primary dystonia. This is important if we wish to use this scale to assess the effect of interventions. We found a minimal detectable difference of 11%, which means that if we wish use the DIS to detect an intervention effect, this effect should be higher than 11% of the total score on the DIS. These findings show that the DIS is a promising tool to assess dystonia and choreoathetosis in individuals diagnosed with inherited or idiopathic dystonia.The aim of chapter two was to develop a shorter, more user-friendly version of the DIS, the DIS-II. To attain this objective, we merged the DIS scores from chapter one with previously collected scores in studies for the DIS development. This combination allowed us to work with a larger set of scores, which is a requirement for the implementation of the Rasch measurement model analysis. Subsequently, we invited clinicians (n=31) from five European countries who had worked with the DIS to a full-day expert meeting to provide input on the included tasks, number of body regions and rating scale steps. Consensus was reached through iterative discussion with the research group, resulting in a proposal for the DIS-II for later evaluation with Rasch analysis. Finally, we used the Rasch measurement model analysis to assess the construct validity and scale reliability of the newly developed scale. Construct validity consisted of rating scale functioning, fit statistics, point-measure correlations and targeting, whereas scale reliability included item and person reliability. Best reliability and construct validity were obtained when using 11 body regions (trunk was excluded) and scoring scale steps from 0 to 2 for rest and from 0 to 3 for action with 3= ‘action not performed’. The DIS-II requires 14 videos to record (instead of 26 for the DIS) and 88 items to score (instead of 144 in the DIS). Rating scale functioning and model fit were good, showing only two misfitting items for the DIS-II in the eye region. These items should thus be interpreted with caution. This is in agreement with the input of the consensus meeting that the eyes are the hardest body region to score, since eye movements often happen unconsciously. The DIS-II showed high internal consistency values and good separation, with individuals being divided into eight severity levels. The DIS-II thus provides a shorter, more user-friendly scale to assess dystonia and choreoathetosis. Additionally, the conversion of percentage scores to interval scores using Rasch conversions can enhance comparison of DIS-II scores over time and between individuals, regardless of the number of actions performed.In chapter three, we focused on upper limb tasks using three-dimensional motion analysis. The movement pattern of individuals with dyskinetic cerebral palsy (CP) is characterized by increased variability due to the presence of dystonia and choreoathetosis, but few information on the psychometric properties of upper limb movements in dyskinetic CP is available. Therefore, we explored the psychometric properties of upper limb kinematics in individuals with dyskinetic CP during the execution of functional tasks. We aimed to explore i) within-session repeatability, ii) variability between individuals with dyskinetic CP and typically developing participants, iii) between-session repeatability and iv) differences in upper limb kinematics between individuals with and without dyskinetic CP. All participants were evaluated using three-dimensional motion analysis during the execution of a reach forward, reach and grasp vertical and reach sideways task and joint angles during task execution were obtained for the trunk, shoulder, elbow and wrist, as well as maximal velocity and trajectory deviation (spatio-temporal parameters). From the joint angles over time, we focused on the joint angle at point of task achievement, i.e. when the participants reach the objective to touch/grasp. All parameters – joint angle at point achievement and spatio-temporal parameters – were calculated for 2,4,6,8 and 10 repetitions and the change in measurement error per number of repetitions was evaluated. We found the lowest change – and thus most stable representation of the movement pattern – after 8 repetitions. This finding indicates that including a higher number of repetitions when evaluating individuals with dyskinetic CP is important to capture their variable movement pattern. Additionally, we found a significantly higher standard deviation for the majority of the joint angles and all spatio-temporal parameters for the dyskinetic CP group, confirming their higher movement variability. We found high between-session repeatability for most of the joint angles, with the exception of elbow pro/supination and scapula angles. For these joints, correct palpation of anatomical landmarks is crucial for their accuracy and should be carefully performed to assure good repeatability over time. Finally, we found higher wrist and elbow flexion, shoulder external rotation and trunk axial rotation at point of task achievement for the dyskinetic CP group, as well as higher trajectory deviation and lower maximal velocity. These findings confirm that individuals with dyskinetic CP have a variable movement pattern, characterized by deviant joint angles in comparison with typically developing peers, but less stereotyped in comparison with individuals with spastic CP.In chapter four, we used the upper limb joint angles over time from chapter three, expanded with data collected in the Netherlands. The objectives of this study were two-fold: First, we explored whether individuals with dyskinetic CP showed higher intra-individual variability of upper limb joint angles over time in comparison with typically developing peers using statistical parametric mapping (SPM). Second, we used non-linear registration SPM to explore time and amplitude differences in the angular waveforms between both groups. SPM identifies significant clusters in a movement cycle, allowing to detect time-dependent differences between upper limb kinematics of two populations. With respect to the first objective, we found that individuals with dyskinetic CP show higher intra-individual variability at the level of all joints, but the occurrence of significant clusters was time-dependent and varied between tasks. At the level of the wrist, intra-individual variability was higher for the dyskinetic CP group for the full reaching cycle during forwards and sideways reaching, and for the first half of the reaching cycle during reach and grasp vertical. At the level of the trunk and shoulder, intra-individual variability was higher for the majority of or the full reaching cycle during all tasks. With respect to the second objective, we found higher mean wrist and elbow flexion for the dyskinetic CP group during all tasks for varying parts of the reaching cycle. These results revealed important information at specific joint levels and specific timings during the movement cycle which can contribute to individualized treatment strategies and assessment of their effect in individuals with dyskinetic CP.In chapter five, we focused on wearable sensors, and more specifically inertial measurement units (IMUs) for the characterization of movement disorders in individuals with a neurological condition. We searched the literature to map sensor set-up, number of sensors, sensor location, included tasks, sensor features extracted from the acceleration and/or angular velocity signal, and significance of the extracted sensor parameters in multiple pathological populations. We identified 101 articles that matched our inclusion criteria, of which 56 researched Parkinson’s Disease (PD). Wrist(s), hand(s) and index finger(s) were the most popular sensor locations. Most frequently included tasks were: finger tapping, wrist pro/supination, keeping the arms extended in front of the body and finger-to-nose. This task inclusion can be explained from the presence of these tasks in the clinical scale to evaluate the symptoms of PD, the Unified Parkinson Disease Rating Scale (or the Movement Disorder Society Revised version). Most frequently calculated sensor features were mean, standard deviation, root-mean-square, ranges, skewness, kurtosis/entropy of acceleration and/or angular velocity, in combination with dominant frequencies/power of acceleration signals. The derived sensor features were dependent of the movement disorder under investigation. Amplitude-related parameters (mean and range of amplitude and amplitude decrement) were used in PD studies and are hypothesized to correlate with hypokinesia (reduction in movement amplitude). Velocity decrement and peak-to-peak, magnitude, and mean of angular velocity were additionally only used in PD studies and are hypothesized to relate to bradykinesia (slowing of movement). Finally, frequency-related parameters were mostly used to characterize tremor in PD and essential tremor. In conclusion, insights from PD studies can accelerate the development of wearable sensors protocols in the remaining pathologies, provided that there is sufficient attention for the standardisation of protocols, tasks, feasibility and data analysis methods.In chapter six, we used the insights gained in chapter five to evaluate the reliability and discriminative ability of sensor features in individuals with and without dyskinetic CP. We placed IMUs on the upper arm, forearm and hand and collected acceleration and angular velocity signals during the execution of a reach forward, reach and grasp vertical and reach sideways task. We evaluated within-and between session reliability of maximal jerk and angular jerk, mean, maximal, root-mean square and sample entropy of acceleration and angular velocity, as well as the differences between the TD and dyskinetic CP group for all features. We additionally evaluated the reliability for all sensor features for long signals (the execution of eight reach forward repetitions) and short signals (one repetition, from hand on the knee to point of task achievement). We found highest reliability for the sensor features based on the long signals, for all features except for sample entropy (within-sessions) and jerk and sample entropy (between sessions). Jerk, angular jerk and maximal acceleration and angular velocity were significantly higher for the dyskinetic CP group in comparison with TD peers. These findings show that wearable sensors are a promising method to detect pathological movement patterns in individuals with movement disorders, providing attractive possibilities for instrumented assessments in a natural environment such as home or school. This can enhance adherence for long-term assessment and increase our insights into the fluctuating patterns depending on stress and arousal levels in individuals with dyskinetic CP." "Neural control of saccades and grasping movements towards objects in space" "Elsie Premereur" "Laboratory for Neuro- and Psychophysiology" "The posterior parietal cortex is important for sensory-motor integration. While the anterior part of the intraparietal sulcus (AIP) is involved in object grasping and stereo processing (Gallese et al., 1994; Durand et al., 2007), a more posterior part (lateral intraparietal area, LIP) has typically been implicated in attention and saccades (Colby et al., 1996; Corbetta and Shulman, 2002). Furthermore, both areas show selectivity for simple 2D shapes (Sereno and Maunsell, 1998; Janssen et al., 2008; Romero et al., 2014). The interplay between area LIP and neighboring area AIP may constitute the neural basis of eye-hand coordination in object manipulation, as human observers always fixate certain landmark positions in a visual scene in which objects have to be grasped (Johansson et al., 2001). Our working hypothesis is that increased activity in anterior LIP neurons and/or posterior AIP neurons– which possess rudimentary shape sensitivity – may identify potential landmark positions on objects in the visual field. Neurons in posterior LIP subserve the planning of eye movements and the shift of attention towards the selected object. Next, AIP neurons will signal the 3D structure of the object-to-be-grasped to plan the appropriate grasp. We will test this hypothesis by simultaneously recording single-unit activity, multi-unit activity and local field potentials throughout the entire intraparietal sulcus during a delayed visually guided grasping task." "Tracking the mind's eye: The role of visuospatial processes in verbal working memory rehearsal." "Department of Experimental psychology" "For decades, the main view has been that working memory (WM) is subserved by separate storage systems, namely verbal and visuospatial WM, with the former rehearsing verbal items through inner speech and the latter rehearsing visual items through internally cycling spatial attention. Yet, recent work has challenged this view and provided evidence that verbal WM also depends on spatial processes. While speech is a continuous stream of input that progresses in time and not in space, it is nevertheless spatially lined up in memory to which principles of spatial attention apply. However, how spatial attention rehearses verbal information that is inherently nonspatial is a mystery. And, what spatial attention actually rehearses is unknown: is it the acoustics or the semantics? The main objective of this project is to reveal the precise link between spatial attention and verbal WM by tracking the mind's eyes in two work packages (WP). As a direct interface of spatial attention, eye-movements may offer a unique opportunity to reveal the online rehearsal mechanisms in verbal WM. In WP1, the spatial context of rehearsal will be tracked by analysing the scan patterns of the eyes, defined as repetitive sequences of fixations which we assume to reflect the iterative cycling process. In WP2, the content of spatial attention will be tracked by measuring pupillary responses during the rehearsal of words, that are known to evoke pupillary changes based on their meaning." "Enhancing the research possibilities of the IMOB driving simulator" "Tom BRIJS" "Rehabilitation Research Center, Traffic Safety, Immunology - Biochemistry" "An expansion of the 2 IMOB's driving simulators with new equipment is described. Four changes are described. First, to investigate underlying neurocognitive processes of driving, Transcranial Magnetic Stimulation (TMS) will be implemented in future research. TMS is a well-established technique to stimulate a well-defined part of the human brain. It can reveal causal brain-behavior relationships providing important information about the underlying neurocognitive processes of driving. To this aim, a repetitive TMS (rTMS) device is necessary. Secondly, a second eye- and head-tracking system is necessary to investigate eye movements while driving in both simulators that are very often in use in parallel. Thirdly, replacement of screen projectors will largely improve overall focus and sign readability in the simulator which is important for our projects on road design. Finally, physical separation of driver and experimenter and a full cab mockup will improve reliability of our driving behavior measurements in all research. All together, this expansion will result in a more complete and reliable picture of driving behavior and will thus increase the impact of our research significantly" "Visual grouping and contour perception." "Johan Wagemans" "Laboratory for Experimental Psychology, Brain and Cognition" "The response to a sensory stimulus depends heavily on its spatial and temporal context. A wide number of studies have investigated contextual effects of perceptual and neurophysiological responses. These studies primarily focused on the primary visual cortex (V1), reporting that responses of V1 classical receptive fields are influenced by the surrounding context. One type of observed contextual modulation in V1 is collinear facilitation, which entails the enhancement of neural responses to an element surrounded by collinear elements. Such facilitatory interactions are thought to form the neural basis of contour perception. The dependence of these interactions on the relative orientation and position of elements has been described in terms of an association field.A number of computational models have used the association field concept to predict human performance in detecting a contour embedded in a background of randomly oriented elements. These models typically construct a saliency map of the image indicating which elements are likely to be part of a contour. Their validity can be assessed by evaluating how well they can predict the image regions that will attract eye movements during contour integration. In the first study, observers' eye movements were recorded during a contour integration task. An association field model was able to predict saccade targets. In addition, we showed that fixation duration and saccade size followed a time course which depended on the saliency and percept of a contour.The results of the first study showed that the presence of potential contours in the image influenced observers' eye movements during contour integration. This suggests that an initial, but still incomplete, saliency map actively guided eye movements. However, it remained unclear which brain processes were involved in the presaccadic selection of a saccade target. In a second study, we aimed to examine whether presaccadic EEG activity is modulated by the presence of a contour or a region with high association strength in peripheral vision. We found that presaccadic EEG activity, mainly over parietal and occipital brain areas, was predictive of the distance between the saccade landing position and the contour. In addition, when a contour was absent, presaccadic activity predicted the association strength at the saccade landing position. Our results suggest that the presaccadic amplitude reflects the degree to which top-down processes can override bottom-up saliency.Other spatio-temporal contextual effects on low-level visual processing have been studied in the context of apparent motion (AM). AM refers to the percept of motion occurring when two stationary stimuli are alternately presented at two different locations. It has been found that the detectability of stimuli is reduced in the presence of AM. Previous studies have attributed such masking to interference caused by AM-induced excitation, claiming that V1 neurons respond as if a stimulus is physically moving. In a third study, we investigated this claim by modelling grating detectability during AM using a physiologically inspired population code model. The model predicted only a small amount of V1 activation, which could not account for the observed masking nor for any perceptual completion of the motion path. Our model revealed that AM masking is instead due to strong suppression of V1 responses, which is consistent with the theoretical framework of predictive coding.A fourth study provided further evidence in favor of AM-induced suppression by measuring and modelling perceived grating contrast during AM. Multiple studies have found that the perceived contrast of a grating is reduced when V1 responses to that grating are suppressed. If AM indeed suppresses neural responses to gratings at the level of V1, the perceived contrast of the grating should be reduced in the presence of AM. A population code model similar to the model presented in the third study provided a full account of performance in a contrast discrimination task. The model indeed revealed a reduction in perceived contrast caused by strong AM-induced suppression. A model only incorporating AM-induced excitation could not account for the data." "Bilingual language comprehension during sentence reading" "Wouter Duyck" "Department of Experimental psychology" "Only a few studies have examined eye movements in bilinguals and none of those was set up with the intention of investigating bilingual sentence processing. The proposed project means to bridge this theoretical gap by gathering a large amount of eye movement data in different groups of bilingual participants (Dutch-English and Dutch-French bilinguals with L2 proficiency and acquisition age varied)." "The short-term persistence of perceptual organization." "Karl Verfaillie" "Laboratory for Experimental Psychology" "The human brain reconstructs the visual world into a perceptual organization, based on the input it receives from the eyes. But what happens when this input becomes temporarily occluded, for instance by an eye blink? In theory the process of reconstruction could start over again, from scratch, when the original input re-appears. However this would be very inefficient. Here, we will investigate how long a previously achieved perceptual organization can persist across such brief interruptions. At the same time, we believe that this persistence relies on more general mechanisms of visual processing, that are also at work when the visual input remains continuously present. The theoretical implications of the current study are therefore not limited to the situation where the input is interrupted. We will then apply the knowledge gained from these studies to a common situation, namely eye movements. When the gaze shifts, the projection of a scene at the back of the eye is rapidly displaced. We will investigate whether perceptual organization persists across this gap in a similar manner as across other gaps, and also why human observers experience the world to be stable even though the input of the eyes to the brain is not." "ArisToCAT - Assessing The Comprehensibility of Automatic Translations" "Lieve Macken" "Department of Translation, Interpreting and Communication" "Machine translation systems cannot guarantee that the text they produce will be fluent and coherent in both syntax and semantics. Erroneous words and syntax occur frequently in machinetranslated text, leaving the reader to guess parts of the intended message. This project (i) analyzes eye movement data to investigate to what extent the lack of predictability in texts that were created by MT impairs comprehension, and (ii) tries to automatically estimate the comprehensibility of machine-translated text. To tackle the first research objective, we will collect and analyze eye movements of participants reading Dutch machine-translated text. In a first experiment we investigate the impact of different categories of MT errors (syntactic versus semantic, function words versus content words, shortdistance versus long-distance triggers of errors) on comprehension. In a second experiment, the participants read six short machine-translated texts of approximately 300-400 words for comprehension. To tackle the second research objective, an MT comprehensibility estimation system for Dutch will be built. The system takes as input a machine-translated sentence and tries to detect the MT errors that seriously hamper comprehension. We start off with a basic system incorporating baseline features such as sentence length and word frequency and gradually add features derived from language models with increasing complexity, namely n-gram, dependency and neural language models.  " "What the eyes don't see, the mind won't learn: Investigating the role of salience in the initial processing of morphology in SLA" "Esli Struys" "Linguistics and Literary Studies" "The cognitive mechanisms of attention and awareness are believed to play a crucial role in the process of second language acquisition (SLA) but little is known about their exact nature and role. Many factors have been proposed to influence a learner’s attention to and awareness of new linguistic forms in a second language (L2), some of which are learner- or context-based and some of which are inherent to the form itself. The latter determine the form’s salience. Many researchers believe the salience of a linguistic form in an L2 critically determines its learning difficulty but little research has investigated this directly and systematically. The present research aims to do just that, by analyzing the eye movements of L2 learners when they encounter new grammatical forms (articles, suffixes) of different types and degrees of saliency while reading texts in a semiartificial language called Englishti. These eye movement reveal how the salience of the form interacts with the attention that learners allocate to it. A questionnaire probes into the level of awareness that learners have of the new form and its meaning while reading. Through a series of experiments that together consider the isolated and interactional effects of various types of salience in combination with learner- and context-specific variables, we expect to develop a more robust understanding of the nature and role of salience in SLA and how this can be applied to improve real-world language learning."