Various Levels of Human Stress & Their Impact on Human Computer Interaction

Abstract: Stress is defined as organism's total response to environmental conditions or stimuli. It actually defines the condition that has an impact on the individual's mental and physical health. Crossing a stress level (threshold) is responsible for the changes. In this paper we discuss how stress plays an important role in human computer interaction (HCI) and how a human interacts with any problem domain. We will discuss human approach on stand-alone systems and certain devices on which user's final outcome will be fixed and well defined. This study is based upon study on two different age group students (16 to 23 and 21 to 28 age group). We find there is unique similarity in behavior of all people towards computer system. As per study we classify human stress in six categories. The stress is changes from one form to other form as per the task. Human stress affects problem solution, solution time and system usability. Human generate various path towards the solution as well as creates various path towards solution to problem statement and this process is discussed in detail in this paper. Keywords— Human Computer Interaction, Stress, Brain Mapping, Performance

I. INTRODUCTION

Stress is a state of human emotion which affects the human behavior and system usability, so when a user starts a system his behavior does affect the usability of the system. When we assign a task to a user then his brain starts working on that particular problem which is the initial state of stress. There is no particular well defined method to calculate human stress, if there is then it is still not that effective. Systems like facial expression recognizer, speech rate calculator, ECG and blood pressure recorder are helpful to analyze the level of stress [2, 3] but for this we have to train and calibrate the system a lot, and the system will not be so much effective, such systems were tested for research in few laboratories but the results were not so convincing as they led to

complex system designs and large number of parameters that were needed to be controlled. So, there is a need to find out more characteristics of human nature, which can be easily recognized by the system. The identified characteristics must be accurate according to the output, so that we can identify the level of stress of human body at the time when user is working on system accomplishing any particular task. It is important for the system to calculate the stress by rate at which user is working and on this basis the system would adjust itself. This would improve the efficiency of the task and ultimately improve the system's usability. If the system is able to give suggestions to the user about how he/she can effectively perform the task in a particular time without increasing his/her level of stress then this could enhance the system’s usability in terms of effectiveness, user satisfaction and learn-ability. To get some outputs, we adopted following methods to get outcome: • Thinking Aloud: Allow the users to test and

analyze their thoughts along with performing test job/tasks [7].

• Co-Discovery: More than one (for better outputs preferred five (Nielsen)) users work on a test interface and share their feelings and insight via conversation while performing test job/tasks [6].

• Formal Experiment: Controlled experiment, face-to-face communication with test users, quality measurements and statistical study and analysis [5].

• Query Techniques: Interviews, surveys and questionnaires [2].

• Usage Studies: Usage data is the cumulative data collected from test users and third-party users who are working on the specified test software and work to accomplish their own tasks. This data is collected over a long period of time [4].

Piyush Saxena Amity School of Engineering &

Technology, Amity University

Noida (U.P.), India piyush.saxena@student.amity.edu

Sanjay Kumar Dubey Assistant Professor

ASET Amity University

Noida (U.P.), India skdubey1@amity.edu

Satyam Saxena Amity School of Engineering

& Technology, Amity University

Noida (U.P.), India satyamsaxena@hotmail.com

II. RESEARCH APPROA

On the basis of human behavior we foutask is assigned to any user then hestrategy in his/her mind (goal is specidefined) and brain builds multiple pathproblem. Basically human mind is able to tracefrom the initial. By the use of multipeven capable of selecting the best path breadth first search or depth first searcis impossible for the human brain to mBest First Search. Human brain works back-propagation. The human stress levtime to time and this defines that usability will increase or decrease. The paths that are recognized are as fol1: problem to solution 2: solution to problem 3: merger approach When user builds these paths then hsome nodes or mile-stones in a particunodes connection contain informatiorequirement of task, completion time stress, failure condition of task and delaFor this, we need to set our goal elements that define a complete problBased on the problem statement, we nehigh-level use case. We need to analyzFor this we need to illustrate the compfor the solution. The approach wilcompute the design pattern and cerdependability. The technical foundations are also an of describing any solution, no matter hhard.

Fig1: Partial representation Problem Solving apby Human Brain

On the part of methodology, our inemphasize on a particular methodoprovide some perspective on how we dinto manageable pieces.

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There are some important aspecsolution. These are more considerations that define commapproach. In this paper, tree nodstate of processes in human brainnode represent initial state of represent the dead nodes, the grthe final states excluding the reqnode represents final desired achieved. Both green node and refinal output state but the differstates is that red node stands foroutput by user” while green nodeoutputs maybe possible using aGreen node may not affect the rcause of knowledge discovoutcomes. More number of used nodes inmean that the required time for more instead it shows more effoduring processing or performance 1. Problem Statement to SolutionIn this methodology the path fostarts from “initial problem solution”. Here final there can solutions because in this approacare possible. For this purpose cerbuilt. Here all the nodes arepresented in different colours inThe problem statement is a milesroot node. Now user divides oseveral parts. These parts come inparent mile-stone or node. Theseinternal nodes. There are somredundancy when compared to These nodes are known as non tenodes form the leaf. The nodes goal state, they also form the leaf more than one method to reach depends upon the route taken up tthe result can be achieved. The difference between top dactual approach use by human bthat one gets more than one outpone as well some extra ones).

Fig2: Problem Statement to Sol

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lution Approach

2. Solution to problem Statement Path In this methodology the path followed by the user starts from “final desired solution to the initial problem statement”. For this purpose we build some mile-stones. Here milestones are the nodes in the diagram. Our problem statement and the solution also behave as milestone as previously defined. The root node is the problem statement. Now user joins several sub-parts, to achieve the solution of problem statement. The advantage of this approach is that it helps in enlarging the problem solving domain to a greater extent still success rate of this approach is lesser than previous one. The basic problem in this approach is to figure out the initial condition, another problem is “it is not certain that we will reach to the desired final problem statement”. This approach is used by user when whole problem solution is well defined.

Fig3: Solution to Problem Statement

Merger Approach Human adopts both types of approaches for decision making. Here, best solution is not considered but appropriate solution is required. Here backtracking is possible depending on the dead node if it comes. It cannot be defined at which step user would adopt backtracking as it depends on his stress level, level of concentration, dead nodes (if reached) and the desired outcome. The methodology that can be opted for traversing can be both ways that is "problem to solution" and "solution to problem" approaches. There is same color coding scheme as in previously defined approaches. There are two major differences with previous approach. First one, the edges are undirected. The undirected edges show that the nodes can travel in both the directions, like in forward and backward approach. Second considerable point is that there is no extra solution node which is appearing in the path. An important issue related to the diagram also states that the start can be selected randomly but skipping of the nodes is not possible. This is the basic cause for sudden change in the stress levels. The red colored node is the goal state node. It is also not possible to skip from one path to another without backtracking to the common node. Once the traversal

point reaches the common node of the two branches, then it is possible to move on to the desired path. Humans use this approach in their daily lives thus they are regarded as intelligent. On the other hand analyzing process is an important cause of knowledge discovery. In the real world traversing from one path to another is possible if the traveler has complete knowledge of the path and the diversions. Similarly predefined knowledge about the different nodes on two different paths can be of greater help to the user thereby saving his time, effort and also reducing the backtracking which seems the only option as in the case of other two approaches. Thus the thorough knowledge of the tree is necessary for the user to choose better, quick and suitable path thereby leading to the desired outcome. Traversing between the nodes of two different paths that belong to the same level may cause no or very low level of stress in this method.

Fig 4: Actual Representation of Solving Problem Statement

Reason behind Stress The main reason behind the stress is user’s switching over from one node to another or from one path to the other. This makes user tired and exhausted and maybe at times he gets motivated and excited due to the positive turn of events and outcomes. This all collectively constitutes and determines the actual stress of an individual thereby defining his stress level in particular. Choosing Right Node The user will need to choose the correct overlap node path to guarantee that he is able to reach the desired node and outcome or result. But in case if the user chooses the wrong node then it may never lead him to the desired outcome. Choosing Wrong node If user opts for a node that fails to find the overlapping nodes, then he/she may be right or wrong according to their decision stress. It will increase or

Initial State

Initial State

Final State

Final State

decrease the level of stress on the user’s mind and in his/her behavior. Wrong decisions may cause back-tracking and delay. Optimal Case If the user is able to connect to the correct node then the stress is the most optimal and the user is highly interactive with the system. This means that the performance will be most optimal. The user will be able to work with ease and for a longer duration with minimal stress. Design Thinking It is a method of practical decree of problems which looks for amplified results for the issues. In this methodology solution based or crucial idea is used to initialize the goal searching in place of initializing from problem state. The method is continued by analysing the current and the future states, the attributes of the dilemma and the solutions are analyzed, concurrently. This kind of opinion happens in the artificial environment. This methodology is different from technical method that initializes by defining the parameters and attributes of the problem state in order to instruct and characterize the results. Rather, the proposed way of problem solving begins from a resolution in order to start with enough number of parameters that need to be defined as well as optimize the path to the destination state as well. The result set in such a state is the starting point. An example of design thinking could have seven stages as follows: 1. Define 2. Research 3. Ideate 4. Prototype 5. Choose 6. Implement 7. Learn. The correct question needs to be asked and more ideas to be developed, thus the optimal solution to be chosen. Although many design fields are in a category somewhere between Stress and usability, they can be referred to their own discrete approach of perception of the world based on a class of result based issue solving, problem determining, production, and aptness in the constructed environment and all this leads to the study and analysis of stress.

III. PROPOSED METHODOLOGY This section of paper deals with the proposed model of stress and levels i.e. how they are defined and efficiency is managed.

Here, stress is defined by the measurement and it’s scaling in the form of states and levels. This scaling can be in the form of stress state levels which is done on the basis of user mouse motion rate, change in number of keys pressed by him in unit time and the strike strength of the user on the keyboard. The strike rate helps to analyze the devotion with which the user is doing to the task and thus helps us analyze the stress that the user is undergoing. Here we do not consider wearing equipments like ECG, we try to define how machine can analyze human behavior without using any extra devices: 1: Calculate the user’s normal strike rate on keys of keyboard and mouse. 2: Mouse movement and its speed rate. 3: Calculate how much time user is in front of system with the help of a webcam or a detector mechanism, so that system is aware of the duration of the time the user is using the system to solve a task. Now need to define the various stress levels according to the effects of the above stated three points. Scales will be graded into six levels. This will describe “how” and “what” are the conditions that affect the user and the usability of the system. The graded scale is as follows:- Level 0: “No Work”- Very less effective work. User is not interested or not working or either is acting to be working. This usually takes place when the interface of the software is either not understood by the user or the user is not getting interest in using the test interface. This happens basically due to lack of training. This level of stress does not affect software usability. This level shows user’s behavior which may be lousy due to availability of time or due to his/her laziness. Level 1: “Slow Work”- Slow work means the user may be busy in other tasks or paying less attention to the task that he/she needs to work upon. This level of stress signifies that user is interested with system either due to lack of understandability or training or other reasons (less time, noise etc). Level 1 stress affects the usability of system and it shows user interaction with system is in the initial phase. Level 2: “Speed Up”- This phase of stress means the user is working on the task and has found some path to solve the problem. The test application is getting easier and adaptable so that user is now able to understand and use the application. User starts developing interest in the application and feels comfortable in using the application. User is able to

use the application at a faster speed and is able to trace the solution. This phase of stress suggests that the user is in learning state and he/she can easily perform knowledge discovery process. User's understandability towards system or system usability is better in this phase. Level 3: “Optimal Speed”- The work goes in the effective and efficient manner in the correct direction of approach towards the solution. This phase suggests that the user is now flexible and feels pretty comfortable in using the test application. He/she has achieved an optimal speed. The usability of system is on peek.This is a constant stress phase, beyond this user interaction towards the system again starts decreasing. Level 4: “Undergoing slow work progress”- The work goes slowly not because of the user knowledge or interaction with the interface but this is due to the physical tiredness and mental fatigue of the user due to his working for long hours. The user needs rest or break to revive his energy levels. After some time of rest the user would either speed up his rate of work or will abort it. The optimal speed in the last level has drained the energy level of the user thereby reducing his speed in spite of good understandability of the application and interest in the work. Level 5: “Abort Work”- The user aborts the task due to selection of the wrong node and needs to backtrack to find the error and to optimize the new solution. Thus user is liable to retry for a better solution to the problem. Thus the outcome is zilch even though it draws a lot of effort of the user. This takes place when the user is not able to move/process a task above a certain level due to un-availability of the goal state or due to selection of the wrong node. Backtracking is not possible in this case so the user is not left with any other option but to abort and start the task all over again.

IV. OUTCOMES

The following points are the outcome of present research: Rules, help, comment are displayed at the time of requirement. 1. User understands the topic well with the help of

live demonstrations (video, image) and examples as compared to any solution statement.

2. Small changes in interface are made in timely manner which may be liked by the user. It increases the attraction towards system.

3. A scale is defined on basis of which the user can be classified thereby his/her level of stress can be calculated on this basis.

4. A user who is working goes through almost all the levels that are defined in this paper and hence once the user level is defined the system can be trained in such a way that it could adjust itself as per the user level and his needs. This would not only enhance the system usability also reduce the stress level of the user.

V. CONCLUSION

The stress level of the user is a pillar stone in defining any system’s usability and its efficiency. This could be done by the analysis of typing rate, stress on hands and probe based detection technique. Stress also depends on the path followed by the user i.e. from problem to solution or vice versa. Defining the stress level of the user one can train the system in such a way that it could not only detect the user’s level but can also modify itself accordingly thereby increasing the usability of the system and also reducing the stress of the user thereby increasing the user satisfaction.

VI. FUTURE SCOPE

This paper significantly shows the methods that can be used for the study of stress level of the user by the system itself to optimize its usability. There can be further use of devices and detectors or techniques such as brain mapping (used in brain fingerprinting) or pulse checker to analyze the stress with more precision. Moreover with more precise analysis of stress one can lead to finer calibration of the state level of the user hence able to design or modify the system interface accordingly and result in better usability of the system.

REFERENCE

[1] Brain's Problem-Solving Function at Work When We Daydream, (2009) - a new University of British Columbia studies. http://www.sciencedaily.com/releases/2009/05/090511180702.html. [2] Ericsson and Simon (1993), Protocol Analysis: Verbal Reports as Data; MIT Press, ISBN 0262550237. [3] Farwell, L. A. and Smith, S. S. (2001). "Using Brain MERMER Testing to Detect Concealed Knowledge Despite Efforts to Conceal." Journal of Forensic Sciences 46,1: 135-143.

[4] Farwell, L.A. (1994) "Method and Apparatus for Multifaceted Electroencephalographic Response Analysis (MERA)," U.S. Patent #5,363,858, Nov. 15, 1994.

[5] Landauer, T., (1988), Research Methods in HCI; In Handbook of HCI, Helander (Ed.), North-Holland, 1988.

[6] Rubin, J. and Chisnell, D, (2008), Handbook of Usability Testing; 2nd Edition, Wiley.

[7] Someren,V. , Barnard, and Sandberg (1994), The Think Aloud Method; Academic Press.