Imagine you knew the answer to a question but the only way you could retrieve it was to draw the solution on a piece of paper. That's exactly what can happen when people are asked to close their eyes and identify a drawn object using only their fingertips to feel its raised outline.
Test yourself by asking someone to apply hard pressure to a piece of a paper while they perform a simple sketch, for example of a tree or car. Have them turn the paper upside down. Hopefully the lines of the sketch should be raised. Close your eyes and attempt to identify the sketch by running your fingertips along the raised outline.
Research shows we're hopeless at recognising drawings in this way. But apparently we can boost our recognition skills by sketching out the information we garnered through our sense of touch, thus allowing us to identify the original object via the sight of our own sketch.
This is uncanny. It means information about the original object is in your brain but is represented in a way that renders it unidentifiable...until, that is, you regurgitate it as a sketch, allowing re-interpretation by your visual system.
Maarten Wijntjes and colleagues first tested the ability of 20 blindfolded participants to recognise several simple embossed drawings, including a hammer, an anchor and a boat. Their accuracy was 49.5 per cent when using one hand to identify the objects, 59.4 per cent when using two hands.
When, after feeling an embossed drawing and failing to recognise it, the participants took off their blindfolds and attempted to sketch the object they'd just felt (now placed out of view), they were subsequently able to identify 28 previously unidentified objects.
Crucially, however, if they kept their blindfolds on during this procedure, the benefit virtually disappeared (only 2 previously unrecognised objects were identified) - thus showing that it is seeing their own sketch that was vital for recognition.
One of the reasons recognition with our fingertips is so difficult is because information about each object comes in serial form - one small part of the outline is experienced at a time. The visual equivalent would be to view the outline of each drawing through a small hole. (Feeling with two hands improves accuracy because it increases the amount of information obtained at once).
Having information about the object stored in your mind in serial form is not ideal for your recognition system. However, when you sketch out the drawing, your visual system can then gulp down the information whole, in a way much more suited for look-up in your mental library.
WIJNTJES, M., VANLIENEN, T., VERSTIJNEN, I., KAPPERS, A. (2008). Look what I have felt: Unidentified haptic line drawings are identified after sketching. Acta Psychologica, 128(2), 255-263. DOI: 10.1016/j.actpsy.2008.01.006
Post written by Christian Jarrett (@psych_writer) for the BPS Research Digest.