Emotional processing encounters many debates about its nature. There is evidence for valence theory, but also for the right hemisphere theory. The aim of this study was to investigate hemispheric asymmetry related to the processing of emotional pictures. To test this theory, an experiment was conducted that consisted of two parts with IAPS pictures. Valence of the pictures was manipulated (pleasant, unpleasant, neutral) as well as the side of the screen where the picture was presented (left/right), while intensity and dominance of presented pictures were controlled. The images were displayed in pairs (neutral/pleasant and neutral/unpleasant) and participants evaluated which picture is pleasant/unpleasant by pressing the key on the left/right side (left/right index finger) on the keyboard, depending on which side of the screen the emotional picture was presented. The assumption was that the answer will be faster for unpleasant pictures presented on the left side which corresponds to pressing the left key and for pleasant pictures the assumption was that there will be a faster response when presented to the right side of the screen which corresponds to pressing the key with the right hand. The results showed the dominance of the left visual field in the processing of emotion or the speed of responding was higher for pleasant and unpleasant images displayed on the left side of the screen and the difference in accuracy scores for detecting the target image was not significant It is shown that in the case of presenting a pleasant image on the left side of the screen, response time was shorter than is the case when they are presented on the right side of the screen. For unpleasant pictures the results were the same, shorter reaction time when the images are presented on the left side of the screen in relation to the case when they are presented on the right side of the screen.