Access to the full text of the published version may require a subscription. However, these strategies are repetitive, monotonous and unsuitable for use with children and young adults. This project explores the design of a game-based therapy programme that aims to support participant engagement and adherence. We first outline requirements for this software, before reporting on the iterative design process undertaken in collaboration with young people, therapists and teachers at a centre for vision impairment. Our work provides insights into the participatory design of games in collaboration with young people with special needs, and reflects upon the tension of balancing game challenge, therapy goals, and accessibility. Furthermore, it highlights the potential of games to empower special populations by providing a medium through which to communicate the subjective experience of specific impairments. Rights

Over the last 150 years, human manual reaction times (RTs) have been recorded countless times. Yet, our understanding of them remains remarkably poor. RTs are highly variable with positively skewed frequency distributions, often modeled as an inverse Gaussian distribution reflecting a stochastic rise to threshold (diffusion process). However, latency distributions of saccades are very close to the reciprocal Normal, suggesting that “rate” (reciprocal RT) may be the more fundamental variable. We explored whether this phenomenon extends to choice manual RTs. We recorded two-alternative choice RTs from 24 subjects, each with 4 blocks of 200 trials with two task difficulties (easy vs. difficult discrimination) and two instruction sets (urgent vs. accurate). We found that rate distributions were, indeed, very close to Normal, shifting to lower rates with increasing difficulty and accuracy, and for some blocks they appeared to become left-truncated, but still close to Normal. Using autoregressive techniques, we found temporal sequential dependencies for lags of at least 3. We identified a transient and steady-state component in each block. Because rates were Normal, we were able to estimate autoregressive weights using the Box-Jenkins technique, and convert to a moving average model using z-transforms to show explicit dependence on stimulus input. We also found a spatial sequential dependence for the previous 3 lags depending on whether the laterality of previous trials was repeated or alternated. This was partially dissociated from temporal dependency as it only occurred in the easy tasks. We conclude that 2-alternative choice manual RT distributions are close to reciprocal Normal and not the inverse Gaussian. This is not consistent with stochastic rise to threshold models, and we propose a simple optimality model in which reward is maximized to yield to an optimal rate, and hence an optimal time to respond. We discuss how it might be implemented.

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Introduction Rehabilitation can improve visual outcomes for adults with acquired homonymous visual field loss. It is unclear, however, whether rehabilitation improves visual outcomes for children because previous training schedules have been tiresome, uninteresting, and have failed to keep them engaged. In this study, we assessed whether children and young people with homonymous visual field loss would adhere to six weeks of unsupervised compensatory training using a specialized video game. Methods Participants aged between 7 and 25 years with homonymous visual field loss completed tabletop assessments of visual search across four site visits. Two baseline assessments separated by four weeks evaluated spontaneous improvements before training began. Participants were then given a copy of the video game to use unsupervised at home for six weeks. Two follow-up assessments separated by four weeks were then conducted to evaluate immediate and acutely maintained effects of training. Results Fifteen candidates met the inclusion-exclusion criteria, nine participated, and eight completed the study. Participants completed an average of 5.6 hours of unsupervised training over the six weeks. Improvements on in-game metrics plateaued during week three of training. The time taken to find objects during tabletop activities improved by an average of 24%–95% CI (2%, 46%)—after training. Discussion The findings demonstrate that children and young people with homonymous visual field loss will engage with gamified compensatory training, and it can improve visual outcomes with less of a time commitment than has been required of adults participating in non-gamified training in previous studies. Appropriately powered, randomized controlled trials are required to evaluate the validity and generalizability of observed training effects. Implications for practitioners Rehabilitation specialists can use specialist video games and gamification technique to engage children and young people with homonymous visual field loss in long-term unsupervised training schedules.

Optokinetic nystagmus (OKN) is a fundamental gaze-stabilizing response found in almost all vertebrates, in which eye movements attempt to compensate for the optic flow caused by self-motion. It is an alternating sequence of slow compensatory eye movements made in the direction of stimulus motion and fast eye movements made predominantly in the opposite direction. The timing and amplitude of these slow phases (SPs) and quick phases (QPs) are remarkably variable, and the cause of this variability is poorly understood. In this study principal components analysis was performed on OKN data to illustrate that the variability in correlation matrices across individuals and recording sessions reflected changes in the noise in the system while the linear relationships between variables remained predominantly the same. Three components were found that could explain the variance in OKN data, and only variables from within a single cycle contributed highly to any given component. A linear stochastic model of OKN was developed based on these results that describes OKN as a triple first order Markov process, with three sources of noise affecting SP velocity, the QP trigger, and QP amplitude. This model was used to predict the degree of signal dependent noise in the system, the duration of the transient state of SP velocity, and an apparent undershoot bias to the QP target location.