Background: 

It is well known that men typically perform better on tests of spatial ability than women. Some authors point out different strategies in decision of visual spatial tasks in men and women. The majority of electrophysiological studies connect gender differences in spatial abilities with cognitive stages of visual processing. Only few authors write about sex differences at early analysis. Method. In our study the sex differences in accuracy, reaction time (RT) and amplitude of the early P1 component of ERPs during recognition of whole and transformed objects. Transformation was a displacement of object details in radial direction and displacement in combination with rotation of details by different angle. Results. The accuracy decreased, and the RT increased parallel to the growth of the rotation angle in both genders. At the same time we found the significant sex differences in the early stage of visual processing. In men the P1 peak amplitude at P3/P4 sites increased significantly during the recognition of spatially transformed objects, and the wider the angle of rotation the greater the P1 peak amplitude. We did not found dependence of amplitude P1 on the rotation of details in women. We also revealed differences of P1 amplitude between correct and incorrect responses. Only in men the errors were connected with decreased P1 amplitude at P3/P4. Conclusion. The revealed gender differences of early visual processing may be the neurobiological basis of different spatial abilities in men and women. The study was supported by Russian Foundation Humanitarian RFH 12-36-01291a2.