JUDGEMENTS OF FRONTAL SLOPE IN NEARBY OUTDOOR SCENES
The appearance of distant slopes is affected by distance foreshortening, so that uphill slopes appear too steep and downhill slopes too shallow. Other factors affect the judgement of nearby slopes on which the observer is standing. Groups of 20 observers at each site were asked to estimate the angular slope in degrees for uphill or downhill views of slopes of 0, 2, 5, 7 and 23 deg. Slope angles were greatly overestimated, with no significant difference between uphill and downhill views. Distance foreshortening is thus unimportant for nearby slopes. Women overestimated more than men. The cause may be their lower ability at spatial tasks and mental rotation.