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Prior to delivery of data, eye tracker software may apply filtering to correct for noise. Although filtering produces much better precision of data, it may add to the time it takes for the reporting of gaze data to stabilise after a saccade due to the usage of a sliding window. The effect of various filters and parameter settings on accuracy, precision and filter related latency is examined. A cost function can be used to obtain the optimal parameters (filter, length of window, metric and threshold for removal of samples and removal percentage). It was found that for any of the FIR filters, the standard deviation of samples can be used to remove 95% of samples in the window so than an optimum combination of filter related latency and precision can be obtained. It was also confirmed that for unfiltered data, the shape of noise, signified by RMS/STD, is around √2 as expected for white noise, whereas lower RMS/STD values were observed for all filters. [ABSTRACT FROM AUTHOR]

A gaze-controlled system was developed to address the specific needs of a person in an advanced stage of Multiple Sclerosis. This patient scored 9 on the EDSS and is representative of a group of patients who can reason normally, but have no functional use of their upper-limbs. The developer and the patient were connected through remote desktop control and could brainstorm a concept to perfection through iterative trial and error. The most important lesson learnt is the importance of user control towards maximum independence. Eventually, the patient was enabled to control his computer efficiently using a novel approach to mouse control together with an on-screen keyboard. He could browse the internet, read e-books, type documents, send and receive e-mails and text messages, draw in a paint application and control his TV through a specially adapted remote control-all by using his eyes to activate commands. The findings suggest that a well-designed eye tracking system can fulfil in the mental and communication needs of patients in this specific category of disability. [ABSTRACT FROM AUTHOR]

It is hypothesized that the number, position, size, and duration of fixations are functions of the metric used for dispersion in a dispersion-based fixation detection algorithm, as well as of the threshold value. The sensitivity of the I-DT algorithm for the various independent variables was determined through the analysis of gaze data from chess players during a memory recall experiment. A procedure was followed in which scan paths were generated at distinct intervals in a range of threshold values for each of five different metrics of dispersion. The percentage of points of regard (PORs) used, the number of fixations returned, the spatial dispersion of PORs within fixations, and the difference between the scan paths were used as indicators to determine an optimum threshold value. It was found that a fixation radius of 1° provides a threshold that will ensure replicable results in terms of the number and position of fixations while utilizing about 90% of the gaze data captured. [ABSTRACT FROM AUTHOR]