Mountains look small

Today I have been skiing in Breuil-Cervinia, in Italian Alps and I have been noting how small the mountains around me looked. Mount Cervino is 4450m tall and the place I have been skiing was at 2500m of altitude. The scenario was similar to the one in the pic beside. No way I could perceive that the peak of the mountain was 2000m (7000ft) above me. I’d rather state that the mountain was at the most 700m higher than where I was.. but by no means I would say that there were 2000m of difference.

I have the feeling that this would be very easily explained if one assumed that the distance (or depth) of the mount is severely understimated: a 2000m mount at 10km of distance projects the same retinal image as a 1000m mount at 5km distance. I have no clue whether this line of thinking makes sense or not(*), however, if all of this were true, it could explain other phenomena, such as Moon Illusion and Dynamic Parallax.

Has anybody ever investigated perception of distance in natural settings (i.e. several kilometers)?

(*) at best one could find data which fit with the concept of distance and size-distance compensation however that is not a proof that such mechanisms do exist..

Visual Illusions on the Wikipedia

I have made a little survey on how many pages on the Wikipedia are dedicated to Optical Illusions and the scenario invites some reflection.

In a first place let’s deal with the voice: “Optical Illusions” . The topic is the best represented one across the Wikipedia network and appears in 20 languages, which is rather good. Universal voices such as “Internet” appear in just about 100 languages however more science-related topics such as “Brain” and “MRI” easily score about 20 or 30 languages. As often, not all the pages in the several languages are exhaustive, however at least 10 languages superseed the one page limit.

It is not here the place where to asses the content of the pages, this is better done in the Wikipedia discussion page, however still a few remarks can be made. Generally speaking the articles are aimed for the general public and they succed in this. However, even keeping things simple, I believe it is still possibile to mention other more in depth arguments such as how optical illusions can help us understanding brain function.

The bad side of the story, it comes when looking for the Visual Illusions entries. The database is not complete at all and various languages offer a different set fo visual illusions. The best way to asses the overall presenece of visual illusions on the site is going to the Wikipedia category “Optical Illusions”. This category contains links to all the visual illusions treated in each language of Wikipedia so, ideally it is the starting page for someone looking for a certain visual illusion. The category “Optical Illusions” appears in 10 languages. Not all the languages have the same number of illusions. English Wikipedia contains 74 pages, French Wikipedia scores 29, German and Spanish Wikipedia contain 20 entries each and Italian Wikipedia only 12. Given that repositories of visual illusions contain up to 100 illusions these figures are relatively small.

I don’t know what you may think of all of this and what you think of the Wikipedia Project. I use the Wikipedia quite a lot and I find it as a good place where to start a web search (either academic driven or curiosity driven) and so many people do. For this reason I think that if we can improve the presence of Visual Illusions on the Wikipedia and increase the quality of the pages it can only be a good thing for our research field.

Comments, as always, are very welcome

Ponzo’s Illusion, the origins

I have heard once that Mario Ponzo worked at FIAT Research Center in Turin in the early XX century and that’s where he synthesized this illusion. I was amazed of reading this: how did he ever come across this illusion? What was he working on? Was it a case of discovery by chance or a deliberate research? If anybody knows more about it, please do post comments or email me.

As a side remark, I have searched Wikipedia for Ponzo’s Illusion and I have found the term only in the English Wikipedia, whereas there is no mention in any other languages nor there is a short biography upon its author. Shouldn’t we make up for this?