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BACKGROUND The evaluation of hindlimb lameness remains a major challenge in everyday clinical practice. In the absence of clear guidelines, veterinarians use different visual assessment methods for this task whose robustness is unknown. OBJECTIVES Determination of the robustness of five visual hindlimb lameness assessment methods based on the comparison of left and right tuber coxae movement. STUDY DESIGN Validated mathematical hindlimb lameness model based on experimental data from the literature. METHODS Vertical movement of left (LTC) and right (RTC) tuber coxae was simulated for the range of common hindlimb lameness movement patterns which horses present with in practice. Lameness severity ranged from sound to moderately lame (0% to 60% movement asymmetry). The scenarios of a pelvis held tilted and asymmetrical pelvic roll were included to reflect possible adaptations in pelvic rotation. Across all conditions, the outcomes for five different visual assessment methods based on comparative tubera coxarum movement were quantified, including hip hike, -drop and range of motion. The robustness of each assessment method was established through comparison to sacrum-based overall movement asymmetry as the ground truth. RESULTS Tubera coxarum based lameness assessment was highly sensitive to all the unique lameness patterns and changes in pelvic rotation which a lame horse may adopt. None of the five visual lameness assessment methods was 100% robust across all conditions tested. For everyday clinical practice, comparing the upward movement amplitude of the RTC before right hind foot contact and of the LTC before left hind foot contact (Hip_hike_diff) would be the most robust single tubera coxarum based visual assessment method. MAIN LIMITATIONS In the absence of published data regarding the frequency of different movement patterns and hip rotation adaptations in clinical practice, this study cannot indicate the proportion of assessments that would be incorrect for a given visual assessment method. CONCLUSIONS Using a single tubera coxarum based visual hindlimb lameness assessment method may lead to incorrect clinical judgement. Therefore, using multiple assessment methods would be beneficial to substantiate impressions.

A large number of lameness indicators have been suggested for the visual equine lameness assessment. However, it remains unknown which of these are commonly used by experts.Twenty-four expert lameness assessors from 10 leading UK institutions viewed 28 video clips of sound and mildly lame horses (median score 2/10). Horses were shown at trot in a straight line (rear and front view) and circle (side view, left and right rein). Eye tracking data were collected at 60 Hz while participants evaluated each clip. A questionnaire captured contextual information.During assessment on the straight line, participants consistently looked mostly at the head and pelvis. On the circle, many participants consistently looked at the head, yet the subsequent choice, weighting and order of examined body regions was unsystematic between and within participants, and there was a bias towards prolonged assessment of the horse's front region. Questionnaires revealed different descriptions of lameness indicators for the same body region and different approaches to decision making under uncertainty.In contrast to reasonably high similarity on the straight line, expert veterinarians have not developed a consistent assessment approach when evaluating horses on the circle. The reliability of various lameness indicators on the circle requires a stronger evidence base for a more systematic, repeatable approach.

Credit card fraud analysis is almost entirely automated. However, there may be occasions when a human analyst is required to intervene. In this paper, we consider situations in which a transaction triggers an automated alert but not sufficiently to allow automated response. On such occasions, automated analysis makes a recommendation as to the fraud pattern that has been identified and the human analyst decides, if this recommendation is correct and what action to take. In order to support the analyst, a “dashboard” can be used to display information that is relevant to the fraud pattern. Thus, a computer could analyze transaction data, define this as a known fraud pattern, and then present the analyst with a dashboard to illustrate how the transaction might fit the pattern. We explore the efficiency with which people respond to the computer's recommendation, and whether computer confidence has an impact on this response. We define efficiency in terms of information search: the user will either have the relevant information on screen or will need to drill-into a dashboard (i.e., open additional windows for information). The results show that participants adapt their decision making to the confidence of the automated support, and, although they drill-down even when not required, are efficient in terms of time spent looking at relevant information.

BACKGROUND Visual assessment of equine lameness is an everyday veterinary task suffering from poor diagnostic accuracy. The aim of this study was to quantify the impact of the perceptual learning game 'LamenessTrainer' on skill development. METHODS Thirty-six undergraduate veterinary students engaged in four game modules teaching the assessment of fore- and hindlimb lameness. Computer animations of horses in this game displayed 0% (sound) to 70% (moderately lame) vertical movement asymmetry of head and pelvis. Performance, learning effects, diagnostic accuracy, detection thresholds and survey responses were analysed. RESULTS Following staircase learning, more than 80% of students reliably classified horses with ≥20% asymmetry for forelimb lameness, ≥40% asymmetry for simplified hindlimb lameness and ≥50% asymmetry for realistic hindlimb lameness. During random presentation, on average 82% of sound and 65% of lame horses were assessed correctly during forelimb lameness evaluation, dropping to 39% of sound and 56% of lame horses for hindlimb lameness. CONCLUSION In less than two hours, systematic perceptual learning through deliberate practice can develop visual assessment skills to an accuracy level comparable to expert assessors scoring the same animations. Skills should be developed further to improve misclassifications of sound and mildly lame horses, especially for hindlimb lameness evaluation.

Research has demonstrated that low vison aids (LVAs) can have a positive impact on the functional sight of those living with sight loss. Step changes in technology are now enabling new wearable LVAs with greater potential than those available previously. For these novel devices to receive increased acceptance and therefore adoption by those with sight loss, visual task demands have to be understood more clearly in order to enable better alignment between device design and user requirements. The aim of this study was to quantify these requirements. Thirty-two participants aged 18 to 87 wore a spectacle-mounted video camera to capture and narrate all everyday situations in which they would use a "perfect" sight aid during 1 week. Captured scenes were analyzed through categorization and computational image analysis. Results showed large variation in activities and lifestyles. Participants reported no available sight aid or coping strategy for 57% of the recorded activities. Reading made up 49% of all recorded tasks, the other half comprising non-textual information. Overall, 75% of captured activities were performed ad hoc (duration of 0-5 minutes), 78% occurred indoors, 58% occurred at home, 48% were lit by natural light, 68% included the object of interest within reach, and 69% required a single focus plane only. Around half of captured objects of interest had a size of 2 degrees visual angle (2.08 logarithm of the minimum angle of resolution [logMAR]) or smaller. This study highlights the need for a sight aid that can make both textual and non-textual scenes accessible while offering flexibility to accommodate individual lifestyles.

PURPOSE Low Vision Aids (LVAs) can have a transformative impact on people living with sight loss, yet the everyday requirements for developing such devices remain poorly understood and defined. This study systematically explored LVA requirements through a structured de-brief interview following a real-world self-recording study. The purpose of this work was to define the actual needs of those living with sight loss so that low vision services can better address them in future. METHODS Thirty-two visually impaired volunteers with varying levels of previous LVA experience participated in a de-brief interview centred around a structured questionnaire. The de-brief followed a one-week real-world study during which participants used recoding spectacles to capture and narrate all situations in which they would use a 'perfect sight aid'. Content and thematic analyses were used to analyse interviews which had the purpose of contextualising these recordings and exploring requirements around psychological, functional and design factors. RESULTS Participants reported that 46% of tasks which they had recorded were most important to them. Of these tasks, 82% were encountered frequently. Few tasks emerged as very important across many participants, the remaining tasks reflecting individual lifestyles or circumstances. Every participant used at least one LVA in their everyday life and 72% identified further coping strategies. Current LVAs identified as consistently poor were distance LVAs, with all other devices receiving mixed or only positive feedback. Around two-thirds of participants would prefer LVA use on an ad-hoc / quick access basis rather than over long periods of time, and just over half would prefer to carry it rather than wearing it all day. Lack of consistency in these responses illustrated potentially different user clusters with divergent design needs. Two-thirds of participants emphasised the desire for a discreet LVA that does not attract attention. However, since half of all participants felt self-conscious in public or in front of other people when wearing the small recording spectacles, this may not be technically achievable. CONCLUSIONS There is a substantial opportunity for new LVAs to address visual needs that traditional devices and coping strategies cannot support. Functional, psychological and design factors require careful consideration for future LVAs to be relevant and widely adopted.

Purpose: To evaluate the efficacy of electronic head-mounted low vision aid (e-LVA) SightPlus (GiveVision, UK, givevision.net) and to determine which people with low vision would see themselves likely using an e-LVA like this. Methods: Sixty participants with low vision aged 18 to 93 used SightPlus during an in-clinic study session based on a mixed methods design. Visual acuity (ETDRS), contrast sensitivity (Pelli-Robson) and reading performance (MNREAD) were measured binocularly at baseline (no device), with the device in ‘normal’ mode (zoom only), and with preferred enhanced mode (zoom and one of four digital image enhancements). At the end of the session, a short questionnaire recorded willingness to use an e-LVA like SightPlus, potential use cases, positive/negative comments and adverse effects. Results: Binocular distance visual acuity improved significantly by 0.63 logMAR on average (p

Decision support systems (DSSs) are being woven into human workflows from aviation to medicine. In this study, we examine decision quality and visual information foraging for DSSs with different known reliability levels. Thirty-six participants completed a financial fraud detection task, first unsupported and then supported by a DSS which highlighted important information sources. Participants were randomly allocated to four cohorts, being informed that the system's reliability was 100%, 90%, 80% or undisclosed. Results showed that only a DSS known to be 100% reliable resulted in participants systematically following its suggestions, increasing the percentage of correct classifications to a median of 100% while halving both, decision time and number of visually attended information sources. In all other conditions, the DSS had no effect on most visual sampling metrics, while decision quality of the human-DSS team was below the reliability level of the DSS. Knowledge of an even slightly unreliable system hence had a profound impact on joint decision making, with participants trusting their significantly worse performance more than the DSSs suggestions.

Visual equine lameness assessment is often unreliable, yet the full understanding of this issue is missing. Here, we investigate visual lameness assessment using near-realistic, three-dimensional horse animations presenting with 0-60 per cent movement asymmetry. Animations were scored at an equine veterinary seminar by attendees with various expertise levels. Results showed that years of experience and exposure to a low, medium or high case load had no significant effect on correct assessment of lame (P>0.149) or sound horses (P≥0.412), with the exception of a significant effect of case load exposure on forelimb lameness assessment at 60 per cent asymmetry (P=0.014). The correct classification of sound horses as sound was significantly (P

Data from 15 jewellery students, in their 1st and 3rd years of training, were analysed to show how data collected from work settings can be used to objectively evaluate performance in the use of tools. Participants were asked to use a piercing saw to cut 5 lines in a piece of metal. Performance was categorised in terms of functional dynamics. Data from strain gauges and a tri-axial accelerometer (built into the handle of the saw) were recorded and thirteen metrics derived from these data. The key question for this paper is which metrics could be used to distinguish levels of ability. Principal Components Analysis identified five components: sawing action; grasp of handle; task completion time; lateral deviation of strokes; and quality of lines cut. Using representative metrics for these components, participants could be ranked in terms of performance (low, medium, high) and statistical analysis showed significant differences between participants on key metrics.

1/ f scaling quantifies the relationship between power spectral density and frequency of a signal by fitting a linear regression model to log-transformed data. Where the fitted slope is zero, the signal is assumed to be white noise arising from a random source, but where there is a negative slope, the signal is assumed to be pink noise arising from a source with metastability. The concept of metastability provides a very useful way of thinking about variability in performance in a dynamic systems framework. In this paper, we demonstrate the application of 1/ f scaling to the study of simple tool-using tasks, with the intention of studying how activity exhibits consistency and variability across individuals and across task demands.

Human monitoring of systems in which sensors provide data to automated decision support algorithms create interesting challenges for Human Factors. In this study we are interested in exploring whether people are able to detect two types of automation failure: when decisions do not fit the data presented to the operator, and when data from different information sources do not agree. For those students that performed at a level of ≥ 97% correct (‘high performers), checking for both types of failure seemed easy. For those students that performed at a level of ≤ 95% correct (‘low performers’), checking for erroneous recommendations seems straightforward, but checking for information agreement seemed to be omitted. One suggestion is that the non-experts expended more effort on checking recommendation and ignored the need to check congruence across displays. The implication is that the ‘worth’ of the displayed information for one task (decision check) outweighed its worth for the simpler task (congruence check) for the non-experts.

Hind limb lameness detection in horses relies on the identification of movement asymmetry which can be based on multiple pelvic landmarks. This study explains the poorly understood relationship between hind limb lameness pointers, related to the tubera coxae and sacrum, based on experimental data in context of a simple rigid body model. Vertical displacement of tubera coxae and sacrum was quantified experimentally in 107 horses with varying lameness degrees. A geometrical rigid-body model of pelvis movement during lameness was created in Matlab. Several asymmetry measures were calculated and contrasted. Results showed that model predictions for tubera coxae asymmetry during lameness matched experimental observations closely. Asymmetry for sacrum and comparative tubera coxae movement showed a strong association both empirically (R(2)≥ 0.92) and theoretically. We did not find empirical or theoretical evidence for a systematic, pronounced adaptation in the pelvic rotation pattern with increasing lameness. The model showed that the overall range of movement between tubera coxae does not allow the appreciation of asymmetry changes beyond mild lameness. When evaluating movement relative to the stride cycle we did find empirical evidence for asymmetry being slightly more visible when comparing tubera coxae amplitudes rather than sacrum amplitudes, although variation exists for mild lameness. In conclusion, the rigidity of the equine pelvis results in tightly linked movement trajectories of different pelvic landmarks. The model allows the explanation of empirical observations in the context of the underlying mechanics, helping the identification of potentially limited assessment choices when evaluating gait.

In this paper we report a cognitive model of how people make decisions through interaction. The model is based on the assumption that interaction for decision making is an example of a Partially Observable Markov Decision Process (POMDP) in which observations are made by limited perceptual systems that model human foveated vision and decisions are made by strategies that are adapted to the task. We illustrate the model by applying it to the task of determining whether to block a credit card given a number of variables including the location of a transaction, its amount, and the customer history. Each of these variables have a different validity and users may weight them accordingly. The model solves the POMDP by learning patterns of eye movements (strategies) adapted to different presentations of the data. We compare the model behavior to human performance on the credit card transaction task.

User interface (UI) design can affect the quality of decision making, where decisions based on digitally presented content are commonly informed by visually sampling information through eye movements. Analysis of the resulting scan patterns - the order in which people visually attend to different regions of interest (ROIs) - gives an insight into information foraging strategies. In this study, we quantified scan pattern characteristics for participants engaging with conceptually different user interface designs. Four interfaces were modified along two dimensions relating to effort in accessing information: data presentation (either alpha-numerical data or colour blocks), and information access time (all information sources readily available or sequential revealing of information required). The aim of the study was to investigate whether a) people develop repeatable scan patterns and b) different UI concepts affect information foraging and task performance. Thirty-two participants (eight for each UI concept) were given the task to correctly classify 100 credit card transactions as normal or fraudulent based on nine transaction attributes. Attributes varied in their usefulness of predicting the correct outcome. Conventional and more recent (network analysis- and bioinformatics-based) eye tracking metrics were used to quantify visual search. Empirical findings were evaluated in context of random data and possible accuracy for theoretical decision making strategies. Results showed short repeating sequence fragments within longer scan patterns across participants and conditions, comprising a systematic and a random search component. The UI design concept showing alpha-numerical data in full view resulted in most complete data foraging, while the design concept showing colour blocks in full view resulted in the fastest task completion time. Decision accuracy was not significantly affected by UI design. Theoretical calculations showed that the difference in achievable accuracy between very complex and simple decision making strategies was small. We conclude that goal-directed search of familiar information results in repeatable scan pattern fragments (often corresponding to information sources considered particularly important), but no repeatable complete scan pattern. The underlying concept of the UI affects how visual search is performed, and a decision making strategy develops. This should be taken in consideration when designing for applied domains.

Pelvic movement is altered in hind limb lame horses. A simple method using one inertial measurement unit (IMU) attached to the sacrum, which objectively measures 'hip hike', will help detecting hind limb lameness in large scale studies. In this study, IMUs over the sacrum and the left and right tuber coxae (TC) quantified vertical movement symmetry (MS) in 10 clinically lame horses. A simple geometrical model was used to estimate TC movement from the sacrum IMU. The differences between measured and estimated MS values (mean±SD) and MS changes during different exercise conditions (straight, circle, flexion) were quantified using established MS parameters to assess the performance of the sacral IMU for estimating TC movement. Mean differences between measured and estimated MS values were variable between horses and ranged from 5 to 30 mm, SD of differences ranged from 7 to 14 mm. However, the difference between measured and estimated change in MS induced by lungeing or flexion test, was lower, with a value

The development of perceptual skills is an important aspect of veterinary education. The authors investigated veterinary student competency in lameness evaluation at two stages, before (third year) and during (fourth/fifth year) clinical rotations. Students evaluated horses in videos, where horses were presented during trot on a straight line and in circles. Eye-tracking data were recorded during assessment on the straight line to follow student gaze. On completing the task, students filled in a structured questionnaire. Results showed that the experienced students outperformed inexperienced students, although even experienced students may classify one in four horses incorrectly. Mistakes largely arose from classifying an incorrect limb as lame. The correct detection of sound horses was at chance level. While the experienced student cohort primarily looked at upper body movement (head and sacrum) during lameness assessment, the inexperienced cohort focused on limb movement. Student self-assessment of performance was realistic, and task difficulty was most commonly rated between 3 and 4 out of 5. The inexperienced students named a considerably greater number of visual lameness features than the experienced students. Future dedicated training based on the findings presented here may help students to develop more reliable lameness assessment skills.

Trotting a horse in circles is a standard and important part of the subjective equine lameness examination, yet objective data on this form of locomotion are sparse. The aim of this study was to investigate the effect of trotting in a circle on head and trunk movement symmetry. Vertical movements of the head, withers, os sacrum and left and right tuber coxae were measured using inertial sensors as 12 sound horses were trotted on a hard surface in a straight line and in a circle on both reins. Seven asymmetry measures and hip hike were calculated for each horse for at least nine strides of comparable stride duration across the three conditions (deviation on horse level ⩽3.7% stride duration). Trotting in a circle introduced systematic changes to the movement pattern of all five body landmarks, affecting most asymmetry measures. On average the asymmetry magnitude was comparable for midline locations between reins and for the tuber coxae on opposite reins with few exceptions, although individual horses showed unsystematic differences between the two reins. The results from this study showed that the thresholds for objective discrimination between lame and non-lame horses will need adjustment on the circle due to the observed asymmetry bias.

Summary Reasons for performing the study: Flexion tests are a common tool during the prepurchase and clinical lameness examination, yet studies quantifying the effect of flexion, apart from distal forelimb flexion in sound horses, are sparse. Objectives: To investigate the effect of proximal hindlimb flexion on perceivable and measurable changes in movement symmetry in horses with objective movement symmetry falling within the margins of ‘sound’. Methods: Thirteen horses, selected based on objective movement symmetry, were instrumented with inertial sensors on left and right tuber coxae and over the os sacrum. Vertical movement symmetry was quantified at trot before and after proximal hindlimb flexion, with a repeat of flexion after 5 min. Video recordings of the horses were assessed visually. Results: Proximal hindlimb flexion introduced additive changes in movement symmetry to the individual baseline movement, with a tendency towards smaller effects with increasing stride number. The main systematic effect was a decrease in upward movement of the os sacrum following mid-stance of the flexed limb and an increase in upward movement following mid-stance of the nonflexed limb, also manifesting in a ‘hip hike’ of the flexed limb; these findings reflected increased movement asymmetry following flexion. Depending on individual baseline asymmetry, flexion can also increase movement symmetry. Conclusions: Proximal hindlimb flexion can exacerbate subtle asymmetry when performed carefully. Variation in measured symmetry following flexion within and between horses showed that the individual response to flexion is highly variable. Potential relevance: Proximal hindlimb flexion may elevate the asymmetry of a slightly lame limb above the threshold for visibility, thus assisting in the clinical gait examination. Further work is needed to examine the causes for a positive response to flexion and possible differences between sound and lame horses as well as horses of different athletic disciplines.

Gait analysis using small sensor units is becoming increasingly popular in the clinical context. In order to segment continuous movement from a defined point of the stride cycle, knowledge about footfall timings is essential. We evaluated the accuracy and precision of foot contact timings of a defined limb determined using an inertial sensor mounted on the pelvis of ten horses during walk and trot at different speeds and in different directions. Foot contact was estimated from vertical velocity events occurring before maximum sensor roll towards the contralateral limb. Foot contact timings matched data from a synchronised hoof mounted accelerometer well when velocity minimum was used for walk (mean (SD) difference of 15 (18) ms across horses) and velocity zero-crossing for trot (mean (SD) difference from −4 (14) to 12 (7) ms depending on the condition). The stride segmentation method also remained robust when applied to movement data of hind limb lame horses. In future, this method may find application in segmenting overground sensor data of various species.

Diversity of expertise at an individual level can increase intelligence at a collective level—a type of swarm intelligence (SI) popularly known as the ‘wisdom of the crowd’. However, this requires independent estimates (rare in the real world owing to the availability of public information) and contradicts people's bias for copying successful individuals. To explain these inconsistencies, 429 people took part in a ‘guess the number of sweets’ exercise. Guesses made with no public information were diverse, resulting in highly accurate SI. Individuals with access to the previous guess, mean guess or a randomly chosen guess, tended to over-estimate the number of sweets and this undermined SI. However, when people were provided with the current best guess, this prevented very large (inaccurate) guesses, resulting in convergence of guesses towards the true value and accurate SI across a range of group sizes. Thus, contrary to previous work, we show that social influence need not undermine SI, especially where individual decisions are made sequentially and then aggregated. Furthermore, we offer an explanation for why people have a bias to recruit and follow experts in team settings: copying successful individuals can enable accuracy at both the individual and group level, even at small group sizes.

Walking and running are two mechanisms for minimizing energy expenditure during terrestrial locomotion. Duty factor, dimensionless speed, existence of an aerial phase, percentage recovery (PR) or phase shift of mechanical energy and shape of the vertical ground reaction force profile have been used to discriminate between walking and running. Although these criteria work well for the classification of most quadrupedal gaits, they result in conflicting evidence for some gaits, such as the tölt (a symmetrical, four-beat gait used by Icelandic horses).We use established pattern recognition methods to test the hypothesis that the tölt is a running gait based on anautomated and optimized decision drawn from four features(dimensionless speed, duty factor, length of aerial phase and PR for over 6000 strides from four symmetrical gaits in seven Icelandic horses) simultaneously. We compare this decision with the use of each of these features in isolation.Sensitivity and specificity values were used to determine optimal thresholds for classifying tölt strides based on each feature separately. Duty factor and dimensionless speed indicate that tölt is more similar to running, while aerial phase and PR indicate that it is more similar to walking.Then, two multidimensional pattern recognition approaches, multivariate Gaussian densities and linear discriminant analysis, were used and it was shown that, in terms of stochastic multidimensional discrimination, tölt is more similar to ‘running’. The approaches presented here have potential to be extended to studies on similar ‘ambling’ gaits in other quadrupeds.

Equine lameness is a significant and challenging part of a veterinarian’s workload, with subtle lameness inherently difficult to assess. This study investigated the influence of trotting speed on perceived and measured changes in movement asymmetry. Ten sound to mildly lame horses were trotted at a ‘slow’, ‘preferred’ and ‘fast’ speed on a hard surface, both on a straight line and in a circle on left and right reins. Video recordings of the horses were visually assessed by six experienced equine clinicians. Vertical movement of head, withers and pelvis was derived from inertial sensor data and several features calculated. On the straight line, more horses were subjectively declared sound at higher speeds, whilst different objective asymmetry measures showed only slight and inconsistent changes. On the circle, speed had no significant effect on the subjective assessment, with an increase in objectively measured asymmetry at higher speeds possibly balanced by a decrease in sensitivity of the observers for this asymmetry. Horses visually examined for subtle lameness on the straight should therefore be evaluated at a slow speed. Trotting speed should be consistent on repeated occasions, especially during objective gait analysis on the circle, to avoid the interaction of treatment effects and speed effects.

Reasons for performing study It is unknown how students develop lameness assessment skills. Objectives To quantify student performance, visual approaches and attitudes to lameness evaluation. Study design Comparison of student cohorts. Methods Twenty 3rd year (inexperienced cohort) and thirteen 4th to 5th year (experienced cohort) students evaluated 30 video clips showing horses on the straight line or circle, followed by a general questionnaire. Eyetracking records (Tobii X102) were collected in parallel. The percentage of correctly evaluated horses was calculated based on verified expert opinion. From the eyetracking records on the straight line, the percentage time spent on different regions on the horse was calculated and compared between cohorts. Results For both cohorts, while the correct detection of lameness per se was high (median ≥92%), detection of the correct limb was lower (median 40–80% depending on quarters and cohort) and detection of sound horses was at chance level (median = 50%). The correct limb was indicated significantly more often by the experienced cohort (P ≤ 0.032) except for forelimb lameness on the circle (P = 0.053). The inexperienced cohort dedicated more time to looking at limb movement, while the experienced cohort focused on head and pelvis movement. Students judged their expected task performance realistically, on average underestimating themselves slightly by around 8%. The task difficulty was rated as a mean (s.d.) of 4.10 (0.48) out of 5 by the inexperienced and 3.35 (0.47) by the experienced cohort. Conclusions Lameness detection skills evolve and improve over the course of the curriculum, with a shift from limb assessment to upper body assessment. Students must learn to reliably determine soundness, and hindlimb lameness proved more difficult than forelimb lameness. Students find lameness detection comparatively difficult, but have a realistic understanding of their skill level, suggesting that they can determine their needs for further practice. Ethical animal research: No animals were used in the study. Video recordings were selected from the archive of R.K. Smith collected during clinical investigations. Explicit owner informed consent for participation in this study was not stated. Sources of funding: S.D. Starke's PhD was funded by the Mellon Trust via the Royal Veterinary College. Competing interests: None.

Introduction The mechanics of circular locomotion are relevant to equine training and lameness evaluation. Circular trotting is associated with asymmetries in upper body movement. This study investigated whether changes in foot placement explain upper body asymmetry and whether this asymmetry is dependent on centripetal force. Methods Six functionally sound horses walked and trotted on a 6 m diameter circle and straight line at their preferred speed. Optical motion capture (Motion Analysis Corp.) recorded foot position in 3D space. For each limb, horizontal foot placement was calculated in a body-based reference system. Vertical displacement asymmetry (Vector Sum, VS) was calculated from inertial sensors (Xsens, The Netherlands) attached above poll, withers, sacrum and tubera coxae. Variables were compared across movement directions and gaits using repeated measures ANOVA (parametric datasets) or Friedman Test (non-parametric datasets). Results Changes in foot placement relative to body position and orientation were small for both gaits in cranio-caudal and medio-lateral direction (maximum effect size at walk/trot: 66/102 mm). The amount of systematic movement asymmetry on the circle was comparable between walk (mean VS head/sacrum: 36/15 mm) and trot (30/15 mm, respectively), despite a 3-fold higher centripetal force during trot. Conclusions Foot placement relative to body position and line of travel does not differ markedly between straight line and circle and cannot solely account for the observed upper body movement asymmetry. Since movement asymmetry was comparable at walk and trot (despite differences in adopted movement pattern), centripetal force may not be the primary variable responsible for movement asymmetry on the circle. Ethical Animal Research The study was approved by the MSU Institutional Animal Care and Use Committee, protocol #06/11-112-00. Sources of funding: Sandra Starke's collaborative research visit for this project was funded by the British Society for Animal Science (BSAS), Murray Black Award. Competing interests: none.

When animals carry loads, there is a proportionate increase in metabolic cost, and in humans this increase in cost is reduced when the load is elastically coupled to the load bearer. Major horse race times and records improved by 5 to 7% around 1900 when jockeys adopted a crouched posture. We show that jockeys move to isolate themselves from the movement of their mount. This would be difficult or impossible with a seated or upright, straight-legged posture. This isolation means that the horse supports the jockey's body weight but does not have to move the jockey through each cyclical stride path. This posture requires substantial work by jockeys, who have near-maximum heart rates during racing.

Reasons for performing study The relationship between pelvic hindlimb lameness pointers remains unclear. Objectives To examine sacrum and tubera coxae (TC) based movement asymmetry across different lameness degrees, patterns and changes in pelvic rotation. Study design Parameter regression and rigid body model. Methods Vertical displacement of left and right tubera coxae (LTC, RTC) and sacrum was quantified experimentally in 107 horses with varying lameness degrees using inertial sensors. To investigate the theoretical relationship between pointers, a geometrical model of pelvis movement was created in Matlab. The model predicts TC movement based on experimentally derived pelvic rotation and computer-generated asymmetrical sacrum movement. Further, the effect of changes in pelvic rotation on TC-based lameness pointers was quantified. For both, experimental and model data, asymmetry measures corresponding to visual assessment strategies of veterinarians were calculated and contrasted. Results Experimental data showed that upward movement amplitudes for sacrum and TC were strongly correlated (r ≥ 0.96). Regression showed that differences were greater between amplitudes of LTC/RTC than sacrum (slope 1.18; r2 = 0.94; P

Introduction The position and magnitude of the ground reaction force (GRF) relative to the hoof influences loading within the limbs. In this study, we investigated changes to the point of force application (PFA) of the GRF in horses walking and trotting on circles compared to a straight line. Methods 8 horses were lunged in 6 m diameter circles (left and right), and led straight, at walk and trot over force plates on firm ground. Hoof-mounted retro-reflective markers were tracked using a motion capture system (Motion Analysis Corp). The PFA was computed in a hoof-local coordinate system during 2018 strides. The instantaneous PFA was weighted by the GRF magnitude to compute an average PFA position within the hoof print for each total stance phase. The average PFAs were analyzed using an ANOVA in which type of locomotion (circle or straight), gait (walk or trot) and hoof (fore or hind) were used as independent variables. A Tukey post-hoc analysis identified pair-wise differences. Results At trot, the PFA moved toward the center of the circle by 19.8 ± 10 mm (mean ± SD, P

Introduction The simplest model of circular locomotion is a point mass moving uniformly on a circle. To produce circular motion, a centripetal force is generated. This study investigated contributions of individual limbs to the net centripetal force in horses trotting on a circle. Methods Six horses trotted on a 6 m diameter circle at their preferred speed. Optical motion capture (Motion Analysis Corp) recorded kinematics, while six force plates (AMTI) recorded ground reaction forces (GRF). Whole body center of mass (CoM) was computed using a 23-segment rigid body model. The GRF of each limb was expressed at the CoM in cylindrical coordinates centered at a best-fit circle of the ground path of the CoM. Average vertical, tangential and radial force components were computed for each limb over the whole stride duration. Forces were analyzed using ANOVA with Tukey HSD post-hoc tests. Results The maximum ground-path deviation of the CoM from the best-fit circle among all trials was only 2.8% of the radius. The forelimbs contributed an average centripetal (radial) force of 0.49 ± 0.16 N/kg (mean ± SD, normalized to body mass), which was significantly greater (P

Introduction Lungeing is part of the standard lameness examination, however it systematically affects movement symmetry even in sound horses. We evaluated a method for objective lameness detection on the circle accounting for this asymmetry bias. Methods Twenty-six horses undergoing lameness examination were equipped with inertial sensors (Xsens) on head, sacrum and tubera coxae. Asymmetry in vertical displacement was quantified for trot on straight line and circle using multiple measures. Horses were classified lame when falling outside the directional reference range of sound horses (directional = ‘normal’ margins and lame limb depending on rein and sign of measure). Objective classification on the circle was compared to subjective evaluation, final diagnoses and objective classification on the straight calculating the proportion of matches. Regression analysis evaluated the association of change in asymmetry between straight line and circle and baseline asymmetry on the straight. Results The match between objective classification on the circle and the exact fore-/hindlimb(s) scored lame subjectively was 81% / 79%. The match with the diagnosed limb(s) was 71% / 85%. There was a high frequency of false positives compared to subjective evaluation. Objective evaluation on the circle added new information compared to assessment on the straight line in 70% (forelimb) / 58% (hindlimb) of instances (contralateral limb lame, bilateral lameness, lame on circle but sound on straight). Change in asymmetry was not associated with baseline lameness (P≥0.062). Conclusions Objective lameness evaluation on the circle makes a valuable contribution to patient assessment: e.g. subtle lameness falling within the margins of ‘normal’ on the straight or bilateral lameness could be identified. In future, the predictive value of the proposed technique should be determined. Ethical Animal Research The study was approved by the local ethics committee. Explicit owner informed consent for participation in this study is not stated. Sources of funding: Sandra Starke's PhD studentship was funded through the Mellon Trust via the Royal Veterinary College. Competing interests: none.