The most astonishing fact is the pace of recognisingspeed at which potentially dangerous animals like snakes. are recognized. The most astonishing fact is the speed at which potentially dangerous animals like snakes are recognized.

Using a passive construction is better here.

This activity takes us only 0,2 second.s. This activity takes us only 0,2 seconds.

This activity takes us only 0,.2 seconds. This activity takes us only 0.2 seconds.

The only time "seconds" is singular is when you are talking about 1 second.

For this reason, we can take advantage of this phenomenon and add pictures to flashcards we review. For this reason, we can take advantage of this phenomenon and add pictures to flashcards we review.

As a foreign language learners we should be aware of the "picture superiority effect". As foreign language learnes we should be aware of the "picture superiority effect".

In numerous studies it ishas been showedn that a human brain processes pictures faster than words. In numerous studies it has been shown that a human brain processes pictures faster than words.

In numerous studies, it is showedn that a human brain processes pictures faster than words. In numerous studies, it is shown that a human brain processes pictures faster than words.

"Shown" is the proper past tense here