How listening to an iPod shrinks your sense of personal space

There you stand on the daily commute, so close to the man in front that you can count each strand of his chin stubble. Behind you, the breath of another traveller gently warms your neck. For a species that likes its space, it's amazing how we cope with the claustrophobia of city life.

Anecdotally, one way we manage is by plugging ourselves into an iPod, creating an invisible, audio-fuelled layer of protection. Now Ana Tajadura-Jiménez and her team have tested this idea scientifically. They asked dozens of participants to walk towards an unfamiliar experimenter (a man or woman) until they got so close it felt uncomfortable. In another condition, the experimenter walked towards the participant, and again the participant indicated when it felt too close. Crucially, this procedure was followed in silence, listening to positive music or listening to negative music. The unfamiliar musical clips, composed for an earlier experiment, were in the style of instrumental movie music. Sometimes the music was played over headphones via an iPod, other times it was played over a speaker system in the room. After the experiment, the participants listened to the music clips again and rated how much they affected them emotionally.

Positive music played over headphones (but not speakers) had the effect of shrinking the participants' sense of personal space, so that the approaching experimenter could walk closer to them before they (the participant) felt uncomfortable. On the other hand, negative music played over speakers (but not headphones) expanded the participants' personal space, so they felt uncomfortable when the approaching experimenter was further away. These effects were most pronounced in the participants who afterwards reported that they'd been affected emotionally by the music to a greater degree. Music made no difference to the participants' sense of personal space when they were the ones walking towards the experimenter.

A possible weakness of the study is that the experimenters could hear the music that the participants were listening to, which may have had a subtle influence on their behaviour. The Digest put this to Dr Tajadura-Jiménez. She told us this was unlikely, since the experimenters were careful to maintain the same neutral expression throughout, and another researcher looked on to ensure consistency across conditions.

"Our study might help to understand the benefit that people find in using personal music players in crowded situations, such as when using the public transport in urban settings," the researchers concluded. "In situations in which there are little possibilities for personal mobility and personal space is constantly compromised, a portable device allowing for a change in the perceived space around would be highly desirable."

The findings chime with an earlier qualitative study in which a homeless man described how he used a personal radio to create his own sense of personal space - an "audio cave" - when out on the streets. The idea that music influences sense of personal space via its emotional effects also tallies with a recent study involving a brain-damaged patient. The woman S.M. had suffered damage to both her amygdala - deep brain nuclei involved in emotional processing - and appeared to have lost her sense of personal space as a result.
_________________________________

Tajadura-Jiménez, A., Pantelidou, G., Rebacz, P., Västfjäll, D., and Tsakiris, M. (2011). I-Space: The Effects of Emotional Valence and Source of Music on Interpersonal Distance. PLoS ONE, 6 (10) DOI: 10.1371/journal.pone.0026083

Post written by Christian Jarrett for the BPS Research Digest.