Reciprocal Tapping Task Research Articles

Investigating Pointing Performance for Tangible Surfaces with Physical 3D Targets

One of the most fundamental interactions –pointing– is well understood on flat surfaces. However, pointing performance on tangible surfaces with physical targets is still limited for Tangible User Interfaces (TUIs). We investigate the effect of a target’s physical width, height, and distance on user pointing performance. We conducted a study using a reciprocal tapping task ( n =19) with physical rods arranged in a circle. We compared our data with five conventional interaction models designed for 2D/3D tasks rather than tangible targets. We show that variance in the movement times was only satisfactorily explained by a model established for volumetric displays ( r 2 =0.954). Analysis shows that movement direction and height should be included as parameters to this model to generalize for 3D tangible targets. Qualitative feedback from participants suggests that pointing at physical targets involves additional human factors (e.g., perception of sharpness or robustness) that need to be investigated further to understand how performance with tangible objects is affected.

Practice-Not Task Difficulty-Mediated the Focus of Attention Effect on a Speed-Accuracy Tradeoff Task.

External focus (attention to the movement effect) has been found effective in motor performance and learning. However, while some investigators have suggested that the effect of attentional focus varies with task difficulty, others reported external focus benefits regardless of difficulty. We hypothesized that attentional focus effects would vary with practice, due to changes in the individual's processing efficiency. We had three 20-person participant groups (external focus instructions, internal focus instructions, control) practice three difficulty levels of a Fitts reciprocal tapping task over two days. Participants in the external/internal focus groups were instructed to "mentally focus on moving the pen/your hand as fast and accurately as possible," while control participants were instructed to "mentally focus only on doing your best to achieve the task goal." We then analyzed the effect of attentional focus by task difficulty at the initial performance (the beginning of the practice) and after learning (the retention/transfer phase), using movement time (MT) and number of error taps (Err) as performance measures. The internal focus group made more errors than the control group only at the retention/transfer phase. We found no error differences between the external and internal focus groups, and there were no MT differences between any groups. Our primary hypothesis about the differential effect of attentional focus by practice was supported. The attentional focus effect on Err differed in the retention/transfer phase from the immediate phase, suggesting that practice mediated the attentional focus effect. We discuss how information theory may supplement understanding of attentional focus interventions in motor skill acquisition.

Evaluation on User Perception Effect based on Interaction Techniques in the Stereoscopic Environment

The interaction of user performance with three-dimensional (3D) objects has become an important issue in the recent development of virtual reality applications. Additionally, the basic conviction of current Virtual Reality (VR) supports the development of the viable interface between humans and machines. The research focuses on the user’s interaction technique by considering two approaches (direct and indirect interaction techniques) for the users while interacting with threedimensional objects. Numerous possible uses can benefit from virtual reality by considering a few fundamental visual and cognitive activities in the Virtual Environment (VE), such as the interpretation of space that users of clear and indirect perception are not well established. The experiment is performed in a stereoscopic environment using a reciprocal tapping task. Participants are expected to use direct pointing as well as indirect cursor techniques to select a stereoscopic spherical target. The results show that, in the sense of a direct interaction technique, user recognition of an object appears to converge in the center of a simulated area. Unfortunately, this convergence is not demonstrated in the indirect cursor situation. The pointing estimation from the users is more accurate when using the indirect interaction approach. The findings provide an understanding of the interaction characteristics done by the users in the stereoscopic environment. Importantly, developers of a virtual environment may use the result when developing effective user interface perception in specific interaction techniques.

Investigation of the parameters affecting the Fitts' law on a reciprocal tapping task

Investigation of the parameters affecting the Fitts' law on a reciprocal tapping task

Using Fitts' Law to Detect Intentional Misrepresentation

ABSTRACTIn paralympic classification, tests of impaired coordination (e.g., reciprocal tapping tasks) are effort dependent and therefore susceptible to intentional misrepresentation of abilities (IM)—deliberate exaggeration of impairment severity. The authors investigated whether reciprocal tapping tasks performed submaximally could be differentiated from tapping tasks performed with maximal voluntary effort, based on conformity with Fitts' law. Ten nondisabled participants performed 14 tapping tasks with their dominant hand on 3 separate occasions. Seven tasks were performed with MVE and the other 7 at speeds that were at least 20% slower. Results revealed that evaluating conformity with Fitts' law is a potentially valid method for objectively detecting IM during reciprocal tapping. Evaluation of sensitivity and specificity of the method is now warranted.

Characterizing non-visual target acquisition tasks with the aid of a tactile display: investigating factors beyond the classical Fitts’ theorem

Interaction in most non-visual environments is limited to discrete units of input and feedback, such as keyboard and sound. The purpose of this study is to use the classical Fitts' law to characterize target acquisition in a non-visual environment with continuous input devices and haptic feedback. Two groups of 21 severely visually impaired volunteers were recruited to perform a series of reciprocal tapping tasks based on three experimental conditions: Fitts' index of difficulty (ID), types of tactile feedback, and the presence of haptic reference points. Types of tactile feedback included continuous vibration, enclosure, and surface friction. The results show that Fitts' law accurately predicts performance for the visually impaired, even though the average movement time (MT) exceeded the 3-s window typical of rapid-aimed movement, particularly when the Fitts' ID is greater than 3 bits. Interestingly, actual distance to the target has a larger effect on MT than target width. Enclosure haptic feedback (i.e., a sudden bump when the mouse pointer crosses over the object boundary) allows participants to rapidly acquire even small targets with a width of only 4 pixels, while varying constant degrees of surface friction are ineffective at conveying distance. Adding a grid of equidistant haptic reference points significantly reduced the number of missed targets and the standard deviation of end clicks around the target center, but increased the overall MT. This paper proposes a model to predict overall MT in non-visual environments with the aid of haptic reference points. These results have implications toward the design of interfaces and input devices that provide continuous control in non-visual environments.

Thumb motor performance varies with thumb and wrist posture during single-handed mobile phone use

Design features of mobile computing technology such as device size and key location may affect thumb motor performance during single-handed use. Since single-handed use requires the thumb posture to vary with key location, we hypothesize that motor performance is associated with thumb and wrist joint postures. A repeated measures laboratory experiment of 10 right-handed participants measured thumb and wrist joint postures during reciprocal tapping tasks between two keys for different key pairs among 12 emulated keys. Fitts' effective index of performance and joint postures at contact with each key were averaged across trials for each key. Thumb motor performance varied for different keys, with poorest performances being associated with excessive thumb flexion such as when tapping on keys closest to the base of the thumb in the bottom right corner of the phone. Motor performance was greatest when the thumb was in a typical resting posture, neither significantly flexed nor fully extended with slight CMC joint abduction and supination, such as when tapping on keys located in the top right and middle left areas on the phone. Grip was also significantly affected by key location, with the most extreme differences being between the top left and bottom right corners of the phone. These results suggest that keypad designs aimed at promoting performance for single-handed use should avoid placing frequently used functions and keys close to the base of the thumb and instead should consider key locations that require a thumb posture away from its limits in flexion/extension, as these postures promote motor performance.

Performance and touch characteristics of disabled and non-disabled participants during a reciprocal tapping task using touch screen technology

Touch screens are becoming more prevalent in everyday environments. Therefore, it is important that this technology is accessible to those with varying disabilities. The objective of the current study was to evaluate performance and touch characteristics (forces, impulses, and dwell times) of individuals with and without a movement disorder during a reciprocal tapping touch screen task. Thirty-seven participants with a motor control disability and 15 non-disabled participants participated. Outcome measures include number of correct taps, dwell time, exerted force, and impulse. Results indicate non-disabled participants had 1.8 more taps than participants with fine motor control disabilities and 2.8 times more than those with gross motor impairments (p<0.05). Additionally, people with gross motor control disabilities demonstrated longer dwell times and greater impulses (p<0.05). The average force used to activate the buttons was 6.2N, although the button activation force was 0.98N. Differences in reciprocal tapping and touch characteristics exist between those with and without motor control disabilities. Understanding how people (including those with disabilities) interact with touch screens may allow designers and engineers to ultimately improve usability of touch screen technology.

Thumb Motor Performance Varies by Movement Orientation, Direction, and Device Size During Single-Handed Mobile Phone Use

The aim of this study was to determine if thumb motor performance metrics varied by movement orientation, direction, and device size during single-handed use of a mobile phone device. With the increased use of mobile phones, understanding how design factors affect and improve performance can provide better design guidelines. A repeated measures laboratory experiment of 20 right-handed participants measured the thumb tip's 3-D position relative to a phone during reciprocal tapping tasks across four phone designs and four thumb tip movement orientations. Each movement orientation included two movement directions: an "outward" direction consisting in CMC (carpometacarpal) joint flexion or abduction movements and an "inward" direction consisting in CMC joint extension or adduction movements. Calculated metrics of the thumb's motor performance were Fitts' effective width and index of performance. Index of performance varied significantly across phones, with performance being generally better for the smaller devices. Performance was also significantly higher for adduction-abduction movement orientations compared to flexion-extension, and for "outward" compared to "inward" movement directions. For single-handed device use, adduction-abduction-type movements on smaller phones lead to better thumb performance. The results from this study can be used to design new mobile phone devices and keypad interfaces that optimize specific thumb motions to improve the user-interface experience during single-handed use.

Use of force plate instrumentation to assess kinetic variables during touch screen use

Touch screens are becoming ubiquitous technology, allowing for enhanced speed and convenience of user interfaces. To date, the majority of touch screen usability studies have focused on timing and accuracy of young, healthy individuals. This information alone may not be sufficient to improve accessibility and usability of touch screens. Kinetic data (e.g. force, impulse, and direction) may provide valuable information regarding human performance during touch screen use. Since kinetic information cannot be measured with a touch screen alone, touch screen-force plate instrumentation, software, and methodology were developed. Individuals with motor control disabilities (Cerebral Palsy and Multiple Sclerosis), as well as gender- and age-matched non-disabled participants, completed a pilot reciprocal tapping task to evaluate the validity of this new instrumentation to quantify touch characteristics. Results indicate that the instrumentation was able to successfully evaluate performance and kinetic characteristics. The kinetic information measured by the new instrumentation provides important insight into touch characteristics which may lead to improved usability and accessibility of touch screens.

Disability and Orientation-Specific Performance during a Reciprocal Tapping Task

Reciprocal tapping tasks have frequently been used to quantify user performance and motor control system function. This experiment used a reciprocal tapping task to examine differences in performance for participants oriented both in front and to the side of a touch screen. Evaluating performance in different orientations for touch screen users is important because public spaces and workplaces may have barriers which preclude touch screens from always being operated from directly in front. Additionally, building design standards may require a wheelchair user in a public building to operate a touch screen from the side because there may not be enough clearance to orient their wheelchair in a manner which allows them to only operate the screen from the front. Participants with motor control impairments affecting the upper extremity and participants without upper extremity motor control impairments completed a study examining reciprocal tapping performance while using a touch screen. Both groups included wheelchair users. Results indicate the orientation of the user, with respect to the touch screen, influences the number of taps which can be completed in five seconds and the amount of force used to activate the buttons. Both variables are negatively affected when the touch screen is oriented to the side of the user. Additionally, users with motor control impairments affecting the upper extremity completed fewer taps and had longer dwell times on the buttons than participants with non-impaired upper extremities. This experiment helps us begin to understand the impact of user-interface position but more research, including more ecologically valid tasks for the user, is needed.

Evaluation of Mouse and Touch Input for a Tabletop Display Using Fitts' Reciprocal Tapping Task

User performance with a tabletop display was tested using touch-based and mouse-based interaction in a traditional pointing task. Dependent variables were throughput, error rate, and movement time. In a study with 12 participants, touch had a higher throughput with average of 5.53 bps compared to 3.83 bps for the mouse. Touch also had a lower movement time on average, with block means ranging from 403 ms to 1051 ms vs. 607 ms to 1323 ms with the mouse. Error rates were lower for the mouse at 2.1%, compared to 9.8% for touch. The high error rates using touch were attributed to problems in selecting small targets with the finger. It is argued that, overall, touch input is a preferred and efficient input technique for tabletop displays, but that more research is needed to improve touch selection of small targets.

Evaluation of Mouse and Touch Input for a Tabletop Display Using Fitts' Reciprocal Tapping Task

User performance with a tabletop display was tested using touch-based and mouse-based interaction in a traditional pointing task. Dependent variables were throughput, error rate, and movement time. In a study with 12 participants, touch had a higher throughput with average of 5.53 bps compared to 3.83 bps for the mouse. Touch also had a lower movement time on average, with block means ranging from 403 ms to 1051 ms vs. 607 ms to 1323 ms with the mouse. Error rates were lower for the mouse at 2.1%, compared to 9.8% for touch. The high error rates using touch were attributed to problems in selecting small targets with the finger. It is argued that, overall, touch input is a preferred and efficient input technique for tabletop displays, but that more research is needed to improve touch selection of small targets.

Clinical Assessment of Motor Function: A Processes Oriented Instrument Based on a Speed‐Accuracy Trade‐Off Paradigm

In this study, we developed a digitizing tablet-based instrument for the clinical assessment of human voluntary movements targeting motor processes of planning, programming and execution. The tool was used to investigate an adaptation of Fitts' reciprocal tapping task [10], comprising four conditions, each of them modulated by three indices of difficulty related to the amplitude of movement required. Temporal, spatial and sequential constraints underlying the various conditions allowed the intricate motor processes to be dissociated. Data obtained from a group of elderly healthy subjects (N = 50) were in agreement with the literature on motor control, in the temporal and spatial domains. Speed constraints generated gains in the temporal domain and costs in the spatial one, while spatial constraints generated gain in the spatial domain and costs in the temporal one; finally, sequential constraints revealed the integrative nature of the cognitive operations involved in motor production. This versatile instrument proved capable of providing quantitative, accurate and sensitive measures of the various processes sustaining voluntary movement in healthy subjects. Altogether, analyses performed in this study generated a theoretical framework and reference data which could be used in the future for the clinical assessment of patients with various movement disorders, in particular Parkinson’s disease.

Visuomotor representation decay: influence on motor systems

The contribution of ventral stream information to the variability of movement has been the focus of much attention, and has provided numerous researchers with conflicting results. These results have been obtained through the use of discrete pointing movements, and as such, do not offer any explanation regarding how ventral stream information contributes to movement variability over time. The present study examined the contribution of ventral stream information to movement variability in three tasks: Hand-only movement, eye-only movement, and an eye-hand coordinated task. Participants performed a continuous reciprocal tapping task to two point-of-light targets for 10 s. The targets were visible for the first 5 s, at which point vision of the targets was removed. Movement variability was similar in all conditions for the initial 5-s interval. The no-vision condition (final 5 s) can be summarized as follows: ventral stream information contributed to an initial significant increase in variability across motor systems, though the different motor systems were able to preserve ventral information integrity differently. The results of these studies can be attributed to the behavioral and cortical networks that underlie the saccadic and manual motor systems.

Attending to the non-preferred hand improves bimanual coordination in children

The effect of attentional focus in bimanual coordination was investigated from a developmental perspective by examining performance of right- and left-handed children, 5–8-years and 9–12-years old, on bimanual reciprocal tapping tasks. Attentional focus was either specified, by asking the children to attend to the preferred or to the non-preferred hand, or unspecified for the execution of the tasks. When attention was oriented to the non-preferred hand we found a reduced movement time and a lower frequency of errors. Performance differences for handedness and age-groups were observed when the children were oriented to attend to the preferred hand or when there was no instruction regarding attention. These differences in performance were eliminated when attention was oriented to the non-preferred hand.

Effects of smoking abstinence on movement regulation.

The effect of smoking abstinence on performance of a reciprocal tapping task was investigated. 6 habitual smokers performed a single-plate and two versions of a two-plate tapping task. Fitts' Law was used to compute an index of difficulty (ID) in bits for the tasks which was 0 bits for the single-plate and 3.32 and 4.17 bits for the two-plate versions of the task. While smoking abstinence had no effect on performance of the single-plate tapping task, it increased movement time on performance of both two-plate task versions. These findings may provide a coherent explanation for the prior findings of nicotine deprivation on psychomotor performance in the literature. This explanation suggests that the effects of nicotine deprivation as incurred through smoking abstinence may be on the central mechanisms regulating information-processing rate for successful movement regulation. Thus nicotine deprivation may not affect performance of simple psychomotor tasks which require minimal information processing but will affect the performance of more complex tasks requiring significantly more information processing for successful movement regulation.

EFFECTS OF SMOKING ABSTINENCE ON MOVEMENT REGULATION

The effect of smoking abstinence on performance of a reciprocal tapping task was investigated. 6 habitual smokers performed a single-plate and two versions of a two-plate tapping task. Fitts' Law was used to compute an index of difficulty (ID) in bits for the tasks which was 0 bits for the single-plate and 3.32 and 4.17 bits for the two-plate versions of the task. While smoking abstinence had no effect on performance of the single-plate tapping task, it increased movement time on performance of both two-plate task versions. These findings may provide a coherent explanation for the prior findings of nicotine deprivation on psychomotor performance in the literature. This explanation suggests that the effects of nicotine deprivation as incurred through smoking abstinence may be on the central mechanisms regulating information-processing rate for successful movement regulation. Thus nicotine deprivation may not affect performance of simple psychomotor tasks which require minimal information processing but will affect the performance of more complex tasks requiring significantly more information processing for successful movement regulation.

Cognitive Strategies During a Reciprocal Tapping Task

Cognitive Strategies During a Reciprocal Tapping Task

Field of View Effects on a Direct Manipulation Task in a Virtual Environment

It is important for designers of virtual reality (VR) systems to understand how properties of the system interact with human processes to impact overall system performance. The following experiments investigated the field-of-view (FOV) characteristics of a VR system and how they affected aimed movement behavior across a natural and virtual environment. Utilizing three levels of FOV, and two levels of task difficulty, subjects performed a reciprocal tapping task. FOV was found to differentially affect movement time performance between the two environments for the moderate level of task difficulty, but not for the more highly difficult level. This significant effect for longer movement times in the virtual environment was traced to the smallest FOV, involving those targets appearing outside the instantaneous FOV. Movement times in the virtual environment were also uncharacteristically nonlinear across target configurations within the same level of difficulty. These findings, as well as other movement time differences between environments, are discussed in terms of image resolution, stereopsis and helmet weight considerations.