  The visual crowding makes it difficult to identify the patterns in peripheral
vision, but the neural mechanism for this phenomenon is still unclear because
of different opinions. In order to study the separation effect of V1 under
different crowding conditions, single-pulse transcranial magnetic stimulation
is applied within the right V1. The experimental design includes two factors:
TMS intensity (10%, 65%, and 90% of the phosphene threshold) and crowding (high
and low) conditions. The accuracy results show that there is a strong
interaction between crowding condition and TMS condition. When the TMS
stimulation intensity is lower than the phosphene threshold, more crowding will
be perceived under the high crowding condition, and less crowding will be
perceived under the low crowding condition. The above results conclude that the
high and low crowding condition separate by TMS stimulation. The results
support the assumption that the crowding is related to V1 and occurs in the
visual coding phase.
