The role of brief presentation times and of the spatial-temporal deficit for the recognition of the shape of visual patterns.

The results of a number of experimental works showed that with brief presentation times the visual system can be perceived as a low-frequency spatial filter. In order to verify this hypothesis, we studied the recognition of clear visual patterns (with full spatial-frequency spectrum) and defocused patterns (with optically cut high spatial frequencies), with brief presentation times. We used the method of constant stimuli (simple geometric figures), which were presented tachystoscopically with preceding and subsequent masking. Two experimental subjects took part in the research. The results show that, contrary to our expectations, clear patterns were recognized better after brief presentation times. This shows that when brief presentation times are used, the high spatial frequencies are also accessible for processing by the visual system, contributing at the same time to the better recognition of shapes.