Illusion of the day

The following illusions created by prof. Kokichi Susihara is at time favorite illusion of mine. Once watched, you feel like you should never really trust what you see.

The video shows a real, constructed scene depicting four slopes with balls that seem to be rolling against gravity. However, the fundamental presumption our eyes makes is wrong. The shading and linear perspective dictate us that this cannot happen. Meanwhile, our eyes are tricked.

Enjoy!

Zombie Vison

Visual perception is an important part of our conscious experience. For us visual people, it's almost impossible to imagine "being conscious" of the surrounding world without a nice, colorful image. We might be used to the notion of subconscious thoughts, but being able to respond to visual stimuli without realizing it is a very counterintuitive idea.

 Actually, there are people who are able to process visual information (to some extent) even though they think they are completely blind to one half of visual field. This rare condition is called blindsight and occurs in patients suffering from cortical blindness, which means nothing is wrong with the eyes or optical nerves and the damage occurs in part of their cortex that is concerned with processing visual information. These patients can tell apart simple stimuli presented in the "blind" part of the field when confronted with forced-answer questions, but they will admit they´re only guessing. Even more surprising is that they can even discriminate between colors while completely lacking any subjective experience of "redness" or "blueness".

Illusion your brain

Visual illusions are particularly interesting phenomena providing insights into mechanisms of how our brain process (mostly) visual stimuli.
All of you might experience illusion of self-motion when travelling by train, perceiving the train moving when the neighbouring train starts moving.
Visual Illusion Contest is an annual event that celebrates scientific endeavour to find new illusions and explain the mechanisms by means of which they work.

In 2010, Jan Kremlacek, a Czech scientist won a third prize for his illusion of rotating double-helix.

One of the winners of this year- the team from prof. Tangen lab- demonstrated an excellent illusion of how a combination of presented stimuli can change the final percept (similarly as Gestalt school of psychology pointed to a century ago). In the video, faces of celebrities turn "ugly" when perceived while focused on fixation cross (a cross in the centre of scene one has to attend).
The explanation could be that using two very different stimuli simultaneously, they can exaggerate a particular feature of each of the pair. More illusions from this and also past years can be found here.

The original illusion:

The altered version (with celebrities):

Now, one could also hope that the opposite effect will be found one day too.