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Psychological Methodology


Self-report data, i.e., data from classic questionnaires, are repeatedly criticized because they have disadvantages that call the validity of the data into question (e.g., memory bias, social desirability, prerequisite of introspection ability). Non-reactive data can be an important complement to reduce or quantify this negative influence. The following Device will be used to collect social contacts and non-reactively - via the number of smartphones in the immediate environment.

Device and technical details

  • The Device is based on an ESP32 microcontroller with a built-in 2.13 inch e-paper display.
  • The device detects Wifi signals and stores them encrypted on a built-in SD memory card.
  • The Device does not store MAC addresses (= physical address of the WLAN sensor) or other personal data of the smartphone. MAC addresses are encrypted by the device after the scanning process, which means that it is no longer possible to draw conclusions about the original MAC address. Regardless of this, almost all smartphones now deliberately use randomized MAC addresses in communication.
  • The device is passive, i.e. the device does not connect to other devices.
  • The Device has a built-in LiPo battery (same type as smartphones) that can be charged via the integrated micro USB port. The device has an automatic charging system - neither over-discharge nor deep discharge can occur.
  • The device always runs for 30 seconds and then goes into a deep sleep mode (i.e. deep-sleep) for 9.5 minutes. During this time, the Device is not active. This allows the Device to run for up to a week without charging.
  • The device is also inactive during the night from 0:00-6:00.
  • The display is a so-called e-paper display (= digital ink), which is very energy-saving.
  • The case was printed with a so-called SLA laser printer and is screwed tight.

Bottom side of the device

Group photo of the devices


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