An open question in neuroscience is “How is the self, the ‘I’ constructed?” The more it is examined, the less simple the idea of the self becomes. There is more than one self for different purposes and the limits of these selves are variable depending on the circumstances. We do not notice these complications because normally our selves coincide, as we would expect. Our bodies can expand to include phantom limbs, fake rubber hands, tools and can shrink with various parts being disowned. There are illusions that affect where we believe we are in space. We can also be fooled to accept actions that are not done by our bodies and not accept ownership of actions that are ours. Menzer and group have investigated a specific illusion: how the timing of footfall sounds affect the feeling of ownership of those sounds. Are the sounds part of the whole experience of walking or do they sound like we are being followed by someone else?
In Menzer’s experiments, subjects walked freely around a course while wearing earphones over which they heard their own foot steps with different delays. They were asked to indicate whether the footsteps were theirs. The walking speeds, auditory delays and agency judgments were recorded.
Confirmatory gait agency judgments (the percentage of “yes” responses) in the experiment decreased rapidly for delays > 120ms and reached a first minimum at 400-500 ms. This is very similar to other reported experiments for various motor tasks and visual as well as audio action signals. This is surprising because the time resolution of auditory and visual systems in different. We can order sounds with an accuracy of about 20ms but agency judgments (both visual and auditory) have values of about 100-200ms. This implies a single mechanism for all the senses – a “who” system. They show that the control of full-body locomotion and the building of a conscious experience of it are at least partially distinct brain processes.
Abstract: A fundamental aspect of the “I” of conscious experience is that the self is experienced as a single coherent representation of the entire, spatially situated body. The purpose of the present study was to investigate agency for the entire body. We provided participants with performance-related auditory cues and induced online sensorimotor conflicts in free walking conditions investigating the limits of human consciousness in moving agents. We show that the control of full-body locomotion and the building of a conscious experience of it are at least partially distinct brain processes. The comparable effects on agency using audio-motor and visuo-motor cues as found in the present and previous agency work may reflect common supramodal mechanisms in conscious action monitoring. Our data may help to refine the scientific criteria of selfhood and are of relevance for the investigation of neurological and psychiatric patients with disturbance of selfhood.
Menzer, F., Brooks, A., Halje, P., Faller, C., Vetterli, M., & Blanke, O. (2010). Feeling in control of your footsteps: Conscious gait monitoring and the auditory consequences of footsteps Cognitive Neuroscience, 1 (3), 184-192 DOI: 10.1080/17588921003743581