FlexType: Flexible Text Input with a Small Set of Input Gestures

In many situations, it may be impractical or impossible to enter text by selecting precise locations on a physical or touchscreen keyboard. We present an ambiguous keyboard with four character groups that has potential applications for eyes-free text entry, as well as text entry using a single switch or a brain-computer interface. We develop a procedure for optimizing these character groupings based on a disambiguation algorithm that leverages a long-span language model. We produce both alphabetically-constrained and unconstrained character groups in an offline optimization experiment and compare them in a longitudinal user study. Our results did not show a significant difference between the constrained and unconstrained character groups after four hours of practice. As expected, participants had significantly more errors with the unconstrained groups in the first session, suggesting a higher barrier to learning the technique. We therefore recommend the alphabetically-constrained character groups, where participants were able to achieve an average entry rate of 12.0 words per minute with a 2.03% character error rate using a single hand and with no visual feedback

Towards Location-Independent Eyes-Free Text Entry

We propose an interface for eyes-free text entry using an ambiguous technique and conduct a preliminary user study. We find that user are able to enter text at 19.09 words per minute (WPM) with a 2.08% character error rate (CER) after eight hours of practice. We explore ways to optimize the ambiguous groupings to reduce the number of disambiguation errors, both with and without familiarity constraints. We find that it is feasible to reduce the number of ambiguous groups from six to four. Finally, we explore a technique for presenting word suggestions to users using simultaneous audio feedback. We find that accuracy is quite poor when the words are played fully simultaneously, but improves when a slight delay is added before each voice

An Ambiguous Technique for Nonvisual Text Entry

Text entry is a common daily task for many people, but it can be a challenge for people with visual impairments when using virtual touchscreen keyboards that lack physical key boundaries. In this thesis, we investigate using a small number of gestures to select from groups of characters to remove most or all dependence on touch locations. We leverage a predictive language model to select the most likely characters from the selected groups once a user completes each word. Using a preliminary interface with six groups of characters based on a Qwerty keyboard, we find that users are able to enter text with no visual feedback at 19.1 words per minute (WPM) with a 2.1% character error rate (CER) after five hours of practice. We explore ways to optimize the ambiguous groups to reduce the number of disambiguation errors. We develop a novel interface named FlexType with four character groups instead of six in order to remove all remaining location dependence and enable one-handed input. We compare optimized groups with and without constraining the group assignments to alphabetical order in a user study. We find that users enter text with no visual feedback at 12.0 WPM with a 2.0% CER using the constrained groups after four hours of practice. There was no significant difference from the unconstrained groups. We improve FlexType based on user feedback and tune the recognition algorithm parameters based on the study data. We conduct an interview study with 12 blind users to assess the challenges they encounter while entering text and solicit feedback on FlexType, and we further incorporate this feedback into the interface. We evaluate the improved interface in a longitudinal study with 12 blind participants. On average, participants entered text at 8.2 words per minute using FlexType, 7.5 words per minute using a Qwerty keyboard with VoiceOver, and at 26.9 words per minute using Braille Screen Input

Detecting social signals from the face

This thesis investigates our sensitivity to social signals from the face, both in health and disease, and explores some of the methodologies employed to measure them. The first set of experiments used forced choice and free naIll1ng paradigms to investigate the interpretation of a set of facial expressions by Western and Japanese participants. Performance in the forced choice task exceeded that measured in the free naming task for both cultures, but the Japanese participants were found to be particularly poor at labelling expressions of fear and disgust. The difficulties experienced with translation and interpretation in these tasks led to the development of a psychophysical paradigm which was used to measure the signalling strength of facial expressions without the need for participants to interpret what they saw. Psychophysical tasks were also used to measure sensitivity to eye gaze direction. A 'live' and screen-based task produced comparable thresholds and revealed that our sensitivity to these ocular signals was at least as good as Snellen acuity. Manipulations of the facial surround in the screen-based task revealed that the detection of gaze direction was facilitated by the presence of the facial surround and as such it can be assumed that gaze discriminations are likely to be made in conjunction with other face processing analyses. The tasks developed in these chapters were used to test two patients with bilateral amygdala damage. Patients with this brain injury have been reported to experience difficulties in the interpretation of facial and auditory signals of fear. In this thesis, their performance was found to depend on the task used to measure it. However, neither patient was found to be impaired in their ability to label fearful expressions compared to control participants. Instead, patient SE demonstrated a consistently poor performance in his ability to interpret expressions of disgust. Vll Experiments 2, 3, 4 and 5 of Chapter 3, have also been reported in Perception, 1995, Vol. 24, Supplement, pp. 14. The Face as a long distance transmitter. Jenkins, J., Craven, B. & Bruce, V. Experiments 1,2,3 and 4 of Chapter 3 were also reported in the Technical Report of the Institute of Electronics Information and Communication Engineers. HIP 96-39 (1997-03). Methods for detecting social signals from the face. Jenkins, J., Craven, B., Bruce, V., & Akamatsu, S. Experiments 2 and 5 of Chapter 3, and a selection of the patient studies from Chapter 6 were reported at the Experimental Psychology Society, Bristol meeting, 1996, and at the Applied Vision Association, Annual Meeting, April, 1996. Sensitivity to Expressive Signals from the Human Face: Psychophysical and Neuropsychological Investigations. Jenkins, J., Bruce, V., Calder, A., & Craven, B

The exterior-letter advantage in linear multi-letter arrays

When linear arrays of unrelated letters (e.g., 'sfdthnc') are presented tachistoscopically centred across a fixation point, letters presented at exterior positions (e.g., 's----c') aregenerally reported more accurately than letters presented in interior positions. This "exterior-letter advantage" suggests that processing is more efficient for exterior letters than for interior letters. Previous researchers have argued that the exterior-letter advantage can be fully accounted for by the influences of lateral interference and mask configuration. However, the processes responsible for the exterior-letter advantage are far from resolved, despite the robustness of the phenomenon and its occurrence in numerous investigations into visual information processing. The experiments reported in this study investigated the role of lateral interference and backward pattern masking in the exterior-letter advantage. To investigate the role of lateral interference, performance was compared across complete 7-letter arrays and arrays in which the presence and proximity of flanking letters was varied by (i) presenting only exterior letters and their immediately flanking interior letter, (ii) varying the number blank letter-spaces by which these letter-pairs were separated, (iii) varying the nature of the characters presented in these displays, and (iv) presenting each exterior/interior letter-pair in isolation. The role of backward pattern masking was investigated (i) using different mask configurations which either matched or exceeded the left and right boundaries of complete letter arrays, and (ii) using masks which overlay only the positions of each exterior/interior letter-pair. The findings indicate that while lateral interference and mask configuration each played a part, neither an imbalance in the number of immediately flanking letters for interior and exterior letters nor mask configuration can entirely account for the exterior-letter advantage