Scientific Staff

Scientific Staff


Assistant professor
Marco van Bommel
 Mo. / Tu. / Wed. / Thu. / Fr.
Building: Cubicus, room C234
Telephone: +31 (0)53 – 489 3915
Secretary: +31 (0)53 – 489 5279 (room C243a)


My work aims to answers the question why people often fail to intervene when they witness a crime or accident. It seems that especially the presence of other bystanders causes people to become less likely and less quick to intervene. This is often called the bystander effect. In previous research I tried to identify specific situations in which the bystander effect does not occur. For my research I often conduct quasi-experiments in the field, such as enacting a theft, or use online communication paradigms.
Related to the bystander effect I studied how the presence of others can diminish the reliability of eye-witnesses and whistle blowers.

Areas of expertise:

  • Bystander intervention
  • Helping behaviour
  • Prosocial behaviour
  • Reputation
  • Group processes


  • Psychology of Safety: 2015-201400122-1A
  • Sociaal gedrag: 2015-201300009-1B
  • Psychology and Crime: 2015-201400580-2A
  • Qualtrics tutorials: 2015-201400579-1B
  • Onderzoeksmethoden en –project: 2015-201400295-2A

Research projects

Currently involved research projects:

  • Bystanders and whistleblowing: When more people are aware of systemic transgression in an organization, does this diminish the likelihood of whistleblowing and the method used to blow the whistle?
  • Social exclusion and bystander intervention: I study the impact of feeling socially excluded on the likelihood of providing social support in the presence of others, or while being alone with only the person in need.
  • Physical arousal and bystander intervention: Can physical arousal predict bystander (non-)intervention?
  • The bystander effect from the victim and perpetrator’s perspective.

Other research interests

  • Bystander intervention in virtual settings.
  • The bystander effect from the perspective of victims and offenders.
  • The role of hormones in bystander intervention.


Peer reviewed:

  • Van Bommel, M., Van Prooijen, J. W., Elffers, H., & Van Lange, P. A. (2016). Booze, Bars, and Bystander Behavior: People Who Consumed Alcohol Help Faster in the Presence of Others. Frontiers in Psychology, 7. Click here to view
  • Van Bommel, M., Van Prooijen, J. W., Elffers, H., & Van Lange, P. A. M. (2014). Intervene to be Seen: The Power of a Camera in Attenuating the Bystander Effect. Social Psychological and Personality Science, 5(4), 459-466.
  • Van Bommel, M., Van Prooijen, J. W., Elffers, H., & Van Lange, P. A. M. (2012). Be aware to care: Public self-awareness leads to a reversal of the bystander effect. Journal of Experimental Social Psychology, 48(4), 926-930.

Non-peer reviewed:

  • Van Bommel, M. (2013). “Ze stonden erbij en keken er naar”. Security Management, issue 12.
  • Van Bommel, M. “De Camera Maakt Heldhaftig”, Reformatorisch Dagblad (Dutch newspaper), issue of 28 October, 2013.