Digital Handwriting with a Finger or a Stylus: A Biomechanical Comparison

A new early warning method for mild cognitive impairment due to Alzheimer's disease based on dynamic evaluation of the "spatial executive process"

Objective

Mild cognitive impairment (MCI) due to Alzheimer's disease (AD), as an early stage of AD, is an important point for early warning of AD. Neuropathological studies have shown that AD pathology in pre-dementia patients involves the hippocampus and caudate nucleus, which are responsible for controlling cognitive mechanisms such as the spatial executive process (SEP). The aim of this study is to design a new method for early warning of MCI due to AD by dynamically evaluating SEP.

Methods

We designed fingertip interaction handwriting digital evaluation paradigms and analyzed the dynamic trajectory of fingertip interaction and image data during "clock drawing" and "repetitive writing" tasks. Extracted fingertip interaction digital biomarkers were used to assess participants' SEP disorders, ultimately enabling intelligent diagnosis of MCI due to AD. A cross-sectional study demonstrated the predictive performance of this new method.

Results

We enrolled 30 normal cognitive (NC) elderly and 30 MCI due to AD patients, and clinical research results showed that there may be neurobehavioral differences between the two groups in digital biomarkers captured during SEP. The early warning performance for MCI due to AD of this new method (areas under the curve (AUC) = 0.880) is better than that of the Minimum Mental State Examination (MMSE) neuropsychological scale (AUC = 0.856) assessed by physicians.

Conclusion

Patients with MCI due to AD may have SEP disorders, and this new method based on dynamic evaluation of SEP will provide a novel human-computer interaction and intelligent early warning method for home and community screening of MCI due to AD.

Evaluating the impact of writing surface and configuration on muscle activation level during a handwriting task: An exploratory study

BACKGROUND: Tablets are ubiquitous in workplaces and schools. However, there have been limited studies investigating the effect tablets have on the body during digital writing activities. OBJECTIVE: This study investigated the biomechanical impact of writing interface design (paper, whiteboard, and tablet) and orientation (horizontal, 45°, and vertical) on tablet users. METHODS: Fourteen adults (7 male, 7 female) participated in a study during which they performed simple writing tasks. Surface electromyography (sEMG) sensors were used to measure upper extremity muscle activation. RESULTS: Results indicate that the effects of writing surface type were most pronounced in forearm muscle activation. Specifically, in the extensor carpi radialis (ECR), where muscle activity was lower on the tablet PC surface. The effects of writing configuration were prominent in the shoulder and forearm. The activation of the flexor carpi ulnaris (FCU) and trapezius muscles was significantly lower in the 45° configuration. An exception to the efficacy of this configuration was the anterior deltoid muscle, which exhibited the lowest muscle activity in the horizontal orientation. CONCLUSIONS: Tablet surface and the 45° configuration resulted in the lowest muscle activation levels. Future studies should include longer experiment duration to investigate the effects of continuous writing.

Measuring Orthographic Knowledge of L2 Chinese Learners in Vietnam Using a Handwriting Task - A Preliminary Report

In the current study, the orthographic knowledge required for writing Chinese characters was assessed among participants with L1 Vietnamese background who learn Chinese as a foreign language. A total of 42 undergraduates were recruited. They were invited to participate in a delayed Chinese character copying task consisting of 32 characters. Their Chinese character reading abilities were also obtained using a character naming task. All the tests were conducted online during the pandemic in 2021. Results indicated that the participants' accuracy in the copying task was affected by the familiarity of the characters and the number of strokes of the characters. These effects minimized as reading performance increased. In the inter-stroke interval (ISI) analysis, results indicated a significant boundary effect where ISIs between orthographic units were longer than ISIs within orthographic units, showing the participants' tendency to chunk Chinese characters into functional units when they write. Only high achievers in the reading task demonstrated the use of both large and small grain-size units in writing (i.e., radical-boundary ISI > logographeme-boundary ISI > non-boundary ISI), while the low achievers only used small grain-size units in their writing. We suggest that the delayed copying task incorporated with handwriting measures is an effective method to assess orthographic knowledge of L2 Chinese learners.

Analysis of postures for handwriting on touch screens without using tools

The act of handwriting affected the evolutionary development of humans and still impacts the motor cognition of individuals. However, the ubiquitous use of digital technologies has drastically decreased the number of times we really need to pick a pen up and write on paper. Nonetheless, the positive cognitive impact of handwriting is widely recognized, and a possible way to merge the benefits of handwriting and digital writing is to use suitable tools to write over touchscreens or graphics tablets. In this manuscript, we focus on the possibility of using the hand itself as a writing tool. A novel hand posture named FingerPen is introduced, and can be seen as a grasp performed by the hand on the index finger. A comparison with the most common posture that people tend to assume (i.e. index finger-only exploitation) is carried out by means of a biomechanical model. A conducted user study shows that the FingerPen is appreciated by users and leads to accurate writing traits.

Features of digitally captured signatures vs. pen and paper signatures: Similar or completely different?

The question of whether digitally captured signatures and conventional signatures executed with a pen on paper differ in their characteristics is of practical relevance for forensic handwriting examiners. Due to gaps in the current literature, the present research is dedicated to this issue. Eighty persons signed in three conditions: a) with a stylus on a pad, b) with an inking pen on a sticky note attached to a signature pad allowing to obtain a digital and an analogue version on paper of one and the same writing simultaneously, and c) with a pen on paper. The first step was to investigate to what extent the character shape and number of pen lifts differ between the digital and analogue representation of one and the same signature. This revealed minor differences which are due to technical characteristics of the devices used. The observed distortions are of minor practical relevance according to ratings by eight participating forensic handwriting examiners. Subsequently, signature characteristics were compared between the three different writing conditions in a casework-oriented way. Statistical multi-level models indicate significant differences between the three signature types, but minor effect sizes in most of the examined characteristics. From the point of view of the participating handwriting examiners, these factors do not fundamentally restrict the comparability between digitally captured and conventional signatures in practice. However, caution should be exercised when generalising the results, as several factors, such as the usage of different signature pads as well as signatures made with the finger instead of a stylus, could result in more important differences compared to pen and paper signatures.

Designing a Tablet-Based Software App for Mapping Bodily Symptoms: Usability Evaluation and Reproducibility Analysis

Background

Symptom drawings are widely used as a qualitative and quantitative method of assessing pain symptoms for both clinical and research purposes. As electronic drawings offer many advantages over classical pen-and-paper drawings, the last years have seen a shift toward tablet-based acquisition of symptom drawings. However, software that is used in clinical care requires special attention to usability aspects and design to provide easy access for physically impaired or elderly patients.

Objective

The aims of this project were to develop a new tablet-based software app specifically designed to collect patients’ and doctors’ drawings of pain and related bodily symptoms and test it for usability in 2 samples of chronic pain patients (Aim 1) and their treating doctors (Aim 2) as well as for test-retest reliability (Aim 3).

Methods

In 2 separate studies, symptom drawings from 103 chronic pain patients and their treating doctors were collected using 2 different versions of the app. Both patients and doctors evaluated usability aspects of the app through questionnaires. Results from study 1 were used to improve certain features of the app, which were then evaluated in study 2. Furthermore, a subgroup of 25 patients in study 2 created 2 consecutive symptom drawings for test-retest reproducibility analysis. Usability of both app versions was compared, and reproducibility was calculated for symptom extent, number of symptom clusters, and the whole symptom pattern.

Results

The changes we made to the app and the body outline led to significant improvements in patients’ usability evaluation regarding the identification with the body outline (P=.007) and the evaluation of symptom depth (P=.02), and the overall difficultness of the drawing process (P=.003) improved significantly. Doctors’ usability evaluation of the final app showed good usability with 75.63 (SD 19.51) points on the System Usability Scale, Attrakdiff 2 scores from 0.93 to 1.41, and ISONORM 9241/10 scores from −0.05 to 1.80. Test-retest analysis showed excellent reproducibility for pain extent (intraclass correlation coefficient, ICC=0.92) and good results for the number of symptom clusters (ICC=0.70) and a mean overlap of 0.47 (Jaccard index).

Conclusions

We developed a tablet-based symptom drawing app and improved it based on usability assessment in a sample of chronic pain patients and their treating doctors. Increases in usability of the improved app comprised identification with the body outline, symptom depth evaluation, and difficultness of the drawing process. Test-retest reliability of symptom drawings by chronic pain patients showed fair to excellent reproducibility. Patients’ usability evaluation is an important factor that should not be neglected when designing apps for mobile or eHealth apps.

Introducing Whole Finger Effects in Surface Haptics: An Extended Stick-Slip Model Incorporating Finger Stiffness

The kinematic serial chain configuration of a finger modulates the frictional properties during tactile exploration tasks. This paper analyzes and subsequently models the effects of the entire finger during sliding operations on a surface. Qualitative and quantitative study of finger movement patterns with postures, sliding directions, and contact angles first indicate the effect of finger stiffness on contact mechanics. A "stiffness ellipse" is subsequently modeled to incorporate finger pose effects, and then coupled with the lumped mass-spring-damper model of the finger pad to estimate resultant contact forces. The performance of the proposed model is verified by comparing with experimental results obtained from ten subjects. The proposed model could estimate the general tendencies of contact forces with change in postures (Extended and Flexed), sliding directions (proximal and distal), and contact angles (20°, 40° and 60°). The experimental results indicate that finger stiffness significantly modulates the contact forces, stick-slip frequency, preloading duration and initial spike during sliding. Introduction of finger posture effects could explain the change in finger normal force during tactile exploration tasks. The proposed haptic rendering model can be used to give a more natural user feedback in virtual fingertip-surface interactions.

Spiral tracing on a touchscreen is influenced by age, hand, implement, and friction

Dexterity impairments are well documented in older adults, though it is unclear how these influence touchscreen manipulation. This study examined age-related differences while tracing on high- and low-friction touchscreens using the finger or stylus. 26 young and 24 older adults completed an Archimedes spiral tracing task on a touchscreen mounted on a force sensor. Root mean square error was calculated to quantify performance. Root mean square error increased by 29.9% for older vs. young adults using the fingertip, but was similar to young adults when using the stylus. Although other variables (e.g., touchscreen usage, sensation, and reaction time) differed between age groups, these variables were not related to increased error in older adults while using their fingertip. Root mean square error also increased on the low-friction surface for all subjects. These findings suggest that utilizing a stylus and increasing surface friction may improve touchscreen use in older adults.