Information for Participant

November 2023, Leiden

Touchscreen behavior and brain functions across the lifespan

Thank you for considering to participate in our study directed towards how brain and behavior alter across the life span – as we age. This study has two parts in terms of the tests conducted and physical location – one part is conducted in the laboratory and the other part is conducted online. You may choose to participate in one or both parts . While we look forward to explaining the details of the experiment please note that it is not mandatory to participate in this study, you can choose to withdraw at any time and you can ask us further questions through the entire study. There is no known medical benefit of participating in these experiments. However, as any remuneration associated with the study depends on your participation and as it takes considerable time to prepare and conduct these experiments, we would much appreciate that you carefully read this document before committing to our study.

Purpose of this study

This study is designed to capture the behavioral and cognitive changes that occur with normal/healthy aging. The targeted period of observation is three years but if the study conditions allow, you may voluntarily extend your participation further. To capture the behavioral changes, we shall exploit day-to-day smartphone and/or tablet touchscreen behavioral logs – which will remain active throughout the entire duration of the study. These logs will enable us to capture for instance how your speed of performance on the touchscreen alters with age. The study further exploits online cognitive tests conducted at a rate of once a month through the entire study period. If participating in the non-invasive brain measurements (optional, EEG), you will additionally spend time in and around the laboratory using your own smartphone while we capture the brain signals and these will sessions be conducted at the rate of approximately once a year through the study period. This rich data collection is expected to reveal how your behavioral alters with age and help narrow the changes in the brain which contribute to the alterations.

Time dedicated to this study

The minimum requirement for participation – and if possible renumeration is to engage in at least ONE test per month which lasts for a maximum of 15 minutes. If you additionally choose to visit us in Leiden for an EEG measurement, the measurement lasts for 4 hours per session (and depends on the availability of measurement resources). These are the targeted durations for the study, but you may choose to take the online tests more frequently without receiving any additional reward and also engage in more frequent EEG measures if resources are available.

Study location

This study occurs online, and if you choose you can additionally participate in the laboratory-based measures conducted at Leiden University (Institute of Psychology, Wassenaarseweg 52).

Communication and coded data collection

Throughout this study period, your email address will be stored for communication purposes. At the end of the study period, the link between this address and all correspondences will be deleted. The data will be collected using random identifiers such as ‘AG99’ or ‘138uue000jxiii19920’. As your email is the primary method for us to communicate with you please do remember to check it during the study period. We will communicate with you via . Please note that this shared mailbox is visible to the research team at Leiden University. At Leiden, we will store your email address (disconnected from any other information) on a secure computer only accessible by the staff at Leiden University. This email may be used in the future to communicate after the study period to either inform of a renewal or to participation in a follow-up study.

Online questionnaires and tests

Our online platform will present a range of short questionnaires and tests. The objective of these tests is summarized here.

Smartphone App operating in the background

If you are an Android user please see below:

You will be asked to install an App (TapCounter) which is designed and implemented by a University of Zurich spinoff QuantActions AG (Zurich, Switzerland). This App tracks your behavior on the smartphone and/or tablet in the background using a unique identifier (such as 138xxxiwhhwhh992ef). The following information is gathered by the App and made available to the research team associated with the unique identifier:

  1. The unique identifier randomly generated by the App as in 138xxxiwhhwhh992ef.
  2. Manufacturer and model of the smartphone as in SAMSUNG A10.
  3. Android operating system version number as in version 10.0.
  4. The timestamp of the touchscreen touch as in 20th Jan 2020, 10h,5m,10s,5ms.
  5. The label of the App in use as in Facebook or Weather.
  6. If your phone was used in portrait or landscape mode.

Please note that ‘4’ and ‘5’ enable us to derive more information such as tapping speed, adjusted according to the type of App in use.

No personally identifiable content as in text messages, images, browsing history or contact information is ever collected.

If you are an iOS (iPhone) user please see below:

  1. The timing of each touchscreen interaction on the provided keyboard.
  2. The time zone of the user’s device.
  3. Timing of the ‘delete’ key.
  4. The timing of a swipe event or the timing if you use autocorrection.
  5. The model of the mobile device on which the app is installed.
  6. The log of battery status.
  7. The label of the App in which the provided keyboard is used, as in Facebook
  8. Data from the CoreMotion API provided by the iOS – all capturing body movements:
    1. Accelerometer
    2. Pedometer
    3. Gyroscope 
    4. MotionActivity': labels such as walking, on a car, on a train etc.
  9. Data from the HealthKit SleepAnalysis API provided by the iOS – quantifying sleep:
    1. Sleep onset
    2. Sleep offset
    3. Sleep quality
  10. Data from the ScreenTime API provided by the iOS – quantifying screen time:
    1. Data from the ScreenTime API provided by the iOS – quantifying screen time:

For both iOS and Android users:

All data is encrypted on the phone and stored securely after un-encryption in Microsoft Azure (operated by QuantActions AG) servers under random codes generated by the App. The data is transmitted from your phone to the cloud preferably in the presence of Wi-Fi connectivity. At no point can these secure servers (operating under the highest-grade industry certifications) link to the email address/es provided by you. This email address to the phone data link is only temporarily made via yet another code when the data is downloaded to a local computer at Leiden University. This allows us to interact with you in case data collection is disrupted or to provide further instructions such as reminders if the expected data is not met. At the same time, it ensures your email address can be never linked to the smartphone data by anyone else other than members of the research team at Leiden. Once the data collection is completed or terminated by you the email will be entirely disconnected from the smartphone data (and in fact all other data) through deletion of the email information and email correspondences.

Short diary on significant life events

If you have been affected by any major life event such as birth, marriage, death of a friend or family member, loss of job, injury, hospitalization or change in residence, please record the time and the nature of event (without mentioning any names or location) in the ‘Notes’ feature of the TapCounter App. Remember, these notes may not be read instantaneously so please use email rather than notes for any correspondence. Although we actively discourage you from entering any personal details like names, dates of birth, email addresses, etc., it is possible that you mistakenly enter personal information here. To ensure your privacy is protected under these circumstances, we will a. never release these notes beyond the research team without first filtering out any unintentionally entered personal details b. use highly secure handling of the data along with industry-standard encryption during transmission.

In laboratory measures

EEG: This is a non-invasive method of measuring brain activity that scans for the small electrical signal changes generated by the brain and detectable on the scalp using specialized electrodes. During these measures, a number of electrodes (between 32 – 64) will be placed on the scalp to record brain activity as you perform certain behavioral tasks such as respond to a sound tone delivered through earphones or tactile stimulation using tiny magnets placed on the fingertips. During these measures, we shall also instruct you to use your own smartphone to capture the corresponding brain signals with the background App running to capture the phone behavior. In preparation for these measurements, you would need to arrive with your hair washed and dried; preferably dried a few hours before the experiment begins. Furthermore, we shall clean the skin areas connecting with the EEG electrodes using medical-grade alcohol. During the EEG session, the following additional data will be gathered: movement sensor recordings from the arms and hands and the 3 d model of your scalp with the EEG electrode locations. During the 3D scanning to create your scalp model we will cover your facial features using a disposable medical mask.

qMCI: This short – 5 min – questionnaire will assess your rough mental status on the day of the EEG experimentation when you visit us in Leiden.

Data distribution and handling

This study will gather data in a coded manner from multiple sources as mentioned above using different software service providers. Irrespective of the form of collection, all of your data will be pooled together on the local computers at Leiden University under unique participation numbers. Below we shall outline the storage of the separate sources and how it is all distributed further to the scientific community and public at large.

The following are the three distinct service providers and the corresponding data handling:

  1. QuantActions, Switzerland (TapCounter App). The smartphone data will be stored for a minimum of 5 years on an Microsoft Azure cloud storage (location EU) linked to the TapCounter App via QuantActions. On this isolated smartphone database, the data will always remain disconnected from your email address and after the study completion, the participation IDs will be further deleted on the cloud to render it truly anonymous.
  2., Strasbourg (Online tests). The coded online testing data will be temporarily stored on the research server administered by (Strasbourg) and stored within the UK/EU until it is downloaded in Leiden. The server is managed by Prof. Sijsbert Stoet. The data on the Psytoolkit server will be disconnected from any demographic information or email. After data collection is completed the data will be deleted from this server and according to Psytoolkit, the deletion will take 24 hours to impact their servers as well. Therefore, the long-term data will be stored at Leiden and released from Leiden.
  3. Leiden University and Microsoft Azure. The email address for signing up on the online tests is stored on Microsoft Azure cloud services in the EU. All the email correspondence and email addresses stored in will be deleted at the end of the study period. Moreover, at the end of the study period the email address stored in Azure will also be deleted . All your data and the corresponding analysis will be reported to the public in anonymized form. When deposited anonymously in a public platform your data may be further processed by the scientific community to discover new patterns of behavior or new brain-behavior relationships and age effects.

Moreover, the email address stored in the cloud (located in the EU and disconnected database than the one used for handling smartphone data via Quantactions) used during the signing up on the online testing platform will also be deleted at the end of the study period.

Furthermore, any data which forms the basis of a discovery reported to the public will be uploaded on public data repositories and on to Dataverse, as per the policies of the Journals that communicate the findings and the unit of Cognitive Psychology. The data will be released using data identifiers which are distinct from the unique identifiers generated by the app but such that it would allow to connect the data when released across separate studies. The repositories can host data indefinitely.


Next to the research data that are being collected to answer the research questions, a number of additional personal data will be collected in the context of the payout of participant compensation (Address, IBAN bank account number and registered name for this bank account). These personal data will be saved separately from the research data and will be shared with the financial administration of Leiden University, who will pass this information on to the Tax Department. The University is legally obliged to report the participant compensation to the Tax Department. Whether or not the Tax Department will make you pay taxes on these cash payments, will depend on your personal situation.

You can also participate in this study without any compensation. At the time of enrolment, we will clearly indicate if compensation is possible.

If participating in the online-only part of the study the compensation is 80 EUR spread over three years. If participating in the EEG experiments in addition, the compensation is 170 EUR spread over three years (under the assumption of 4 hours of participation per year). You may choose to collect your compensation once a year or wait until the end of the study. The annual targets of one test per month must be met to receive the compensation. Exceptions (for instance, missed tests due to illness or vacations) will be explicitly approved by the research team.

The compensations are calculated based on the rate of 3.50 EUR per 30 min of online experimentation and 7.50 EUR per h for EEG experiments. Moreover, for the online tests (as they sometimes take only 10 min), an indicator will show you the compensation amount accumulated. For the online test, only a maximum of one test can be rewarded per month but you can choose to do more without any compensation.

You may also be compensated for referring the data collection platform to a friend at the rate of 5 EUR per a successful referral. This compensation is only available if you reside in the Netherlands (as is any compensation in this study). A referral is considered successful only if the referred user uses the unique promotion code passed-on by you during the registration, and remains in the study for a period of 1 year. After this period, the reward amount can be requested for payment together with your bank details as explained above. You will be able to review the number of referrals on your dashboard at any time (when logged-in). This referral rewards program will become unavailable for new referrals as soon as the target recruitment is completed and you shall be explicitly informed of this via this website dashboard (when logged-in). This is entirely optional and has no other bearing on the study.

For University of Leiden students performing online tasks, the following reward structure applies. 1 Credit is offered for 30 min of online tasks. This corresponds to performing 2 recommended online tasks for 1 Credit, and a maximum of 4 credits can be obtained by performing 8 recommended tasks. The minimum duration for remaining in the study to receive any credit is 2 months. It is possible to remain in the study for paid or voluntary participation upon termination of the credit period and then general participation commitment applies.

Exclusion criteria

We are sorry that if you answer any of the following in affirmative, we cannot include you in this study:

  1. You SHARE your smartphone with others
  2. You are LESS than 16 years of age
  3. You are diagnosed with a CURRENT neurological or mental health condition
  4. Any of your fingers are dysfunctional or suffered from permanent injury
  5. You do not have an email address
  6. You cannot easily access a desktop or laptop (public or private) computer
  7. In case volunteering for in lab measures: you have highly sensitive skin
  8. In case volunteering for in lab measures: require mobility assistance

Withdrawal from experiment

You can withdraw at any time. To withdraw from the study, simply send an email to the research team or uninstall the App. You do not need to provide us with any reasons for your withdrawal but if you provide one, we shall record the reason along with the historical (pre-withdrawal) data. In case the withdrawal is via uninstallation of the app, the research team may contact you via email to confirm the withdrawal. These are the consequences of the withdrawal:

  1. Any app data collected after the withdrawal is deleted.
  2. You will get a written confirmation of the withdrawal.
  3. Your email and all correspondences are deleted pending compensation.
  4. Your data is rendered anonymous for long-term storage, analysis and distribution.
  5. You will get compensation according to the set rate if you have participated for at least 1 year.
  6. All data collected prior to the withdrawal is not deleted.

As mentioned in ‘f’, we are unable to delete your historical data mainly as the data is intermittently processed and the partial data is routinely backed-up on local computers at Leiden University after true anonymization (by deletion of the email address to ID link).

For more information on data privacy and your rights, please check the European Union’s data privacy law, known as the General Data Protection Regulation (“GDPR”).

NOTE: Your withdrawal from the study can only be executed once you install the App from your phone. If you wish to continue using the App after withdrawal, uninstall and reinstall again.

Contact information

Arko Ghosh, Cognitive Psychology Unit, Institute of Psychology, Leiden University

You can also contact Arko Ghosh if you have a complaint. If you prefer not to do so, you can contact the Contact point for research participants at the Faculty of Social Sciences of Leiden University:

If you have any questions or complaints about your privacy or the processing of your personal data, you can contact the privacy officer of Leiden University: