# Is tactile perception two-dimensional or three-dimensional?

Is tactile perception two-dimensional or three-dimensional? Can tactile sense be mapped on 2-dimensional map of the surface of the human body or does human receive tactile signal as a 3D position (owing that internal organs can also feel pain)?

It's not 2D: Tactile perception can very simply understand a ring around your finger. If you projected the skin of your body onto a 2D plane there would be a way to represent this sensation, but only as an irregular shape. So you need a third dimension to cognitively process this sensation.

But Phantom pain tells us the brain doesn't always register tactile perception from a true 3D mapping. For example a person without an arm could feel pain in a finger that doesn't exist. Not always, but sometimes.

So it's greater than two, and sometimes three doesn't fully describe the known phenomena. Therefore it's (at least) 4-D.

• Hmmm I don't get how phantom pain affects the number of dimensions. Jul 8, 2014 at 0:43

Well, vision is 2D * 2 (two retinae) but visual perception is 3D, auditory signal is 1D * 2 (two ears), but its perception is 3D. The 3D perception in these senses are results of analysis of the lower dimensional sensory signal combined with various other internal states. (Internal states can integrate information over time to produce better percepts.)

Likewise, each tactile sensor is a point source, but the percept of the total tactile sensory stimuli is 3D; I can tell where the source of the sense is in 3D space relative to my body position. The signals will have to be combined with the proprioception and state information in the brain to do so.

Note that these 3D percepts don't always work perfectly. Sometimes we form the wrong percept or fail to get a percept.

• Sorry, but you cannot hear in 3D using 2 ears in any case. It is mathematically impossible. Apr 7, 2014 at 21:58
• @Anixx but you can. Head transfer function and prior knowledge. It's mathematically possible, although not always the case. Apr 8, 2014 at 13:00
• @Anixx en.wikipedia.org/wiki/Vertical_sound_localization combined with other cues, not perfectly, but possible. Apr 8, 2014 at 13:10