Distances toward zenith are perceived as longer than physically equal distances towards horizon. Reason for this anisotropy might be in better action performance, since, in order to reach something towards zenith, we oppose gravity, and if perceived distance is longer, we would put more effort and easily oppose gravity. If this is true, action towards the ground would be in line with gravity, and perceived distance would be shorter. We tested this hypothesis in two experiments in which 27 participants (14+13) had the task to equalize the perceived distances of stimuli on three directions (horizontal, tilted 45 degrees and vertical). In the first experiment tilted and vertical directions were toward zenith, and in the second toward the ground. One of the stimuli was the standard, and participants matched distances of other two with the standard. Results of the first experiment show significant difference in matched distances between 0 and 45 degrees (F(1,13)=67.17, p<0.01), 0 and 90 degrees (F(1,13)=122.76, p<0.01), 45 and 90 degrees (F(1,13)=41.49, p<0.01). For the second experiment, results show significant difference between 0 and 45 degrees (F(1,12)=12.85, p<0.01), 0 and 90 degrees (F(1,12)=29.89, p<0.01), and no significant difference between 45 and 90 degrees direction. Participants matched longer horizontal distances with shorter distances toward zenith, meaning that perceived distances toward zenith were longer. On the other hand, they matched shorter horizontal distances with longer distances towards the ground, meaning that perceived distances towards the ground were shorter. Both of these findings are in line with our hypothesis.

anisotropy, perceived distance, gravity, perception and action, viewing direction