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By: Tuuli Pöllänen

This is a repository for a web application containing a psychological experiment I conducted for my master's thesis, to explore cognitive skills and team cohesion in League of Legends players. The experiment consists of an informed consent, a survey for demographic information, two questionnaires, four cognitive tasks, and a finish-page for comments and feedback. If you want to see the experiment 'in action', you can visit, and if you'd like to shuffle through the paper I wrote, you can do so here.

The complete structure of the experiment is as follows:

  1. Landing page - informed consent
  2. Demographic items
  3. Group Environment Questionnaire
  4. Nasa Task Load Index
  5. Eriksen Flanker task
  6. Two-dimensional mental rotation task
  7. Spatial Span task
  8. Tower of London
  9. Finish page

All of the individual parts of the experiments have their own views, under the views folder, with .ejs extensions (I used the EJS template engine since it works well with raw html).

The experiment and its purpose

The purpose of the experiment was to explore the role of cognitive skills in predicting players' performance in different play styles in League of Legends - a multiplayer online battle arena game. Additionally, I was interested in players' perceptions of their task load during game, and how team cohesion relates to performance in teams.

Instruments and their implementation

The experiment consists of two questionnaires and four cognitive tasks. Additionally, there is an informed consent, explaining the purpose and the structure of the study with general instructions, followed up by a survey of demographic items, such as player name, region, level, rankings, team name etc. After the cognitive tasks, there is a finishing page inquiring whether the participants would like to be contacted with the results of the study.

The questionnaires

The questionnaires were constructed using a modified Likert-plugin for JsPsych - a JavaScript library for creating web-experiments. All of the jsPsych plugins used for the test battery can be found in public/scripts/plugins.

The Group Environment Questionnaire

The Group Environment Questionnaire (GEQ) was chosen as a measure of group cohesion because it is well established with a long history of use in sports psychology and group research, with recent evidence suggesting adequate multilevel factorial validity (Fletcher & Whitton, 2014). An instrument from sports psychology was preferred over those from organizational psychology, as interviews with players indicated that the items meant for athletic teams were considered more relevant to their gameplay experience. The players' satisfaction with the instrument drove the decision of not developing a new instrument for the purpose, but rather attempting to repurpose GEQ. The items were modified slightly to match the context of virtual games (e.g. using the word "players" instead of "athletes"), and the modified items can be found in Appendix 1. The goodness-of-fit of a sports psychology inventory for the purpose of this study is something that should be taken into account in interpreting the results of this study.

GEQ is a general, rather than situation-specific measure of cohesion in sports teams. It consists of the following four sub-scales forming a four-factor model of cohesion (Brawley, Carron, & Widmeyer, 1987):

  • Group Integration–Social (GI-S) conceptualizes a team member's assessment of the group's closeness, similarity and bonding as a social unit - for example, “members of our team do not stick together outside of practices and games”.
  • Group Integration–Task (GI-T) conceptualizes the member's assessment of the group's closeness, similarity and bonding around the group's task - for example, “our team is united in trying to reach its goals for performance”.
  • Individual Attractions to the Group–Social (ATG-S) conceptualizes to the member's notions of the social interactions and personal acceptance within the team, for example “some of my best friends are on this team”.
  • Individual Attractions to the Group–Task (ATG-T) conceptualizes a member's feelings about personal involvement related to the group's common goals and productivity - for instance, “I do not like the style of play on this team”.

The NASA Task Load Inventory (TLX) was selected as a well-established, short task load inventory with good metric characteristics (Hart & Staveland, 1988; Hart, 2006). The instrument originally consisted of two parts. In the first part, six sub-scales are presented on a single page, with the following description of each of the scale:

  1. Mental Demand: How much mental and perceptual activity was required? Was the task easy or demanding, simple or complex?
  2. Physical Demand: How much physical activity was required? Was the task easy or demanding, slack or strenuous?
  3. Temporal Demand: How much time pressure did you feel due to the pace at which the tasks or task elements occurred? Was the pace slow or rapid?
  4. Performance: How successful were you in performing the task? How satisfied were you with your performance?
  5. Frustration: How irritated, stressed, and annoyed versus content, relaxed, and complacent did you feel during the task?
  6. Effort: How hard did you have to work (mentally and physically) to accomplish your level of performance?

The items are rated on a 100-points range with 5-points increments. In the original version, the second part of the inventory creates individual weighing by importance for each of the six subscales by prompting the subjects to compare the categories pairwise based on their perceived importance for the task load. The estimated task loads are then weighed according to their importance. The version used for this study, however, consists of only the first part of the original test, without the pairwise comparisons. This modification was done to simplify the study design, with evidence indicating that this procedure (referred to as the Raw TLX) is as sensitive as the original instrument (Hart, 2006).

The cognitive tasks

JsPsych - a JavaScript library for writing experiments for behavioral sciences - was used in many of the experiments, with some modifications (e.g. how the data objects were constructed and with appending feedback messages after successful or unsuccessful trials).
Eriksen flanker task

The Eriksen flanker task was composed utilizing the jsPsych-categorize plugin for the training trials, and the jsPsych-single-stim plugin for the trials themselves.

The Flanker task used for this experiment was programmed roughly in a similar manner to the Flanker task in the PEBL library (Mueller & Piper, 2014), which was based on Stins, Polderman, Boomsma and deGeus (2007). During the task, the participant is presented with images of five arrows in a row. Their task is to press the arrow key corresponding to the direction of the middle arrow, which points either to the same direction as the arrows flanking it (a congruent trial) or to the opposite direction (incongruent trial).

The measures gained on the Flanker task are the speed and accuracy in responding to congruent vs. incongruent trials. Difference between the response time in correct congruent and incongruent trials is a rough measure of executive function, as it indicates the strength of the interference effect.

Two-dimensional mental rotation task

The mental rotation task was composed using a new plugin I wrote for jsPsych that allows forced choice comparison of two stimuli (jspsych-two-stim). The task contained three types of two-dimensional stimuli. Stimulus A consisted of one long line, perpendicularly intersected by two short ones. Stimulus B and C were similar to the stimulus A, except that they had one and two diagonal lines added to them, respectively. During the task, the participants were presented with an unrotated version of the target stimulus, and a version of the stimulus that was either an identical or mirrored version of the target, and rotated 0, 60, 120, 180, 240 or 300 degrees. The two images were displayed side-by-side, and the target stimulus was randomly displayed on either left or right side. The participant was instructed to assess as quickly and accurately as possible, whether the rotated image was identical or a mirror image of the target, and to press Q if they were identical and P if mirrored.

Several cognitive measures can be extracted from the results in the mental rotation task, comparing accuracy and response times at different stimulus complexity in mirrored vs. identical conditions at different degrees of rotation.

The Spatial Span task

The spatial span is a cognitive test for assessing a person's visuospatial working memory, as the maximum digit span of spatial elements recalled in a two-dimensional sequence. The version here was written as a stand-alone experiment without jsPsych, and it was programmed similar to that of Owen and Hampshire (n.d.) as a variation of the Corsi block tapping task (Corsi, 1972). The stimuli were displayed as flashing rectangles in a four-times-four matrix of rectangular elements. After the stimulus was generated, the participant had to click on the boxes in the same order in which they flashed. The first stimulus had a length of four blocks, trial difficulty was lowered after two failures on the same stimulus length and increased after successful completion. The task was concluded after four failures.

The Tower of London

The Tower of London (a task that assesses skills in planning and problem solving) also utilizes the jsPsych-categorize plugin. It consists of twenty-two pairs of images. The first image, image A, displays a starting point with three pegs of different lengths and of three balls of different colors, and image B displays an ending point with a final layout. The participant was asked to assess the smallest amount of moves they could use to get from the layout in image A to the layout in image B, and to respond by pressing the corresponding key on the keyboard. The moves required for the trials varied between one and six.


You are free to use individual parts of the experiment for your own purpose, with the following citation:

Pöllänen, T. (2014). Test battery of JavaScript-based cognitive tasks. Github repository. Retrieved from

Note that you can change the style in the experiment by just altering the CSS (unless you really enjoy the League of Legends game art).

How to set up the experiment

I'll only cover how to run the experiment locally! You will have to consider your options if you wish to set it up on your own server and domain (if there are enough requests, there will be a tutorial on how to deploy jsPsych experiments as node.js apps on my blog at .

To run the experiment locally, fork the repository and set up a local MySQL database from thesis_database.sql. Then, write a file called database.json to your root folder (where your app.js is located), with the following structure:

    "driver": "mysql",
    "user": "[your username]",
    "database": "[database name]",
    "password": "[password]"

This is a node.js application, so you will need to set up node.js and its package manager on your computer. Once you have those set up, you install the depencies by going to the root directory and typing npm install into your terminal. The package manager will automatically install the dependencies described in the package.json:

"dependencies": {
    "express": "4.9.4",
    "ejs": "1.0.0",
    "body-parser": "1.8.3",
    "express-myconnection": "1.0.4",
    "logger": "0.0.1",
    "sequelize": "2.0.0-rc1",
    "mysql": "2.5.1",
    "node-uuid": "1.4.1",
    "serve-static": "1.6.2",
    "validator": "3.19.1",
    "mobile-detect": "0.4.1"

You can start the application locally by typing node app.js in the root folder. This will start the application on port 3000, so you can access the page through localhost:3000.


Carron, A. V., Widmeyer, W. N., & Brawley, L. R. (1985). The development of an instrument to assess cohesion in sport teams: The Group Environment Questionnaire. Journal of Sport Psychology, 7, 244-266.

Fletcher, R. B. & Whitton, S. M. (2014). The Group Environment Questionnaire: A Multilevel Confirmatory Factor Analysis. Small Group Research, 45(1), 68-88. doi: 10.1177/1046496413511121

Hart, S. G. & Staveland, L. E. (1988). Development of NASA-TLX (Task Load Index): Results of empirical and theoretical research. In: Human Mental Workload (P. A. Hancock and N. Meshkati (Eds.)), 139-183. North-Holland: Elsevier Science.

Hart, S. (2006). Nasa-Task Load Index (Nasa-TLX); 20 Years Later. Human Factors and Ergonomics Society Annual Meeting Proceedings, 50, 904-908.

Mueller, S. T., & Piper, B. J. (2014). The Psychology Experiment Building Language (PEBL) and PEBL Test Battery. Journal of neuroscience methods (222), 250–259.

Stins, J. F., Polderman, T. J. C., Boomsma, D. I., & de Geus, E. J. C. (2007). Conditional accuracy in response interference tasks: Evidence from the Eriksen flanker task and the spatial conflict task. Advances in Cognitive Psychology 3 (3), 389–396.

Corsi, P.M.(1972), Human memory and the medial temporal region of the brain, Unpublished doctoral dissertation. McGill University.

Owen, A. M. & Hampshire, A. (n.d.). Spatial span ladder [software for online web-based testing]. Cambridge Brain Sciences Inc, University of Western Ontario, Canada. Retrieved from


Test battery of JS cognitive tasks written using jsPsych for my master's thesis






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