- A sense of rhythm and speed, and therefore of flow.
- An overall orientation (based on the sum of fragment orientations) and therefore a sense of direction.
- A smooth dynamic on account of their linear fragments' gradual changes in orientation.
- A feeling of enclosure because curves are fragments of circular/elliptical circumferences.
- if the orientation of the curve fragment and the straight line is the same (i.e. parallel), then there is low dynamic tension, and a reinforcement of flow.
- if the orientation of the curve fragment to the straight line is perpendicular (i.e. at a right-angle), then there is high dynamic tension and a redirection of flow to the radial centre of the curve (i.e. the curve's focal point).
- curves interact less with the image frame, because dynamic tension is not maintained over the length of their relationship.
Curves cannot be artificed by the photographer (without the use of a fish-eye lens, in which case, then everything in the image will be curved), they have already to exist in real life perhaps by momentary implication. What can be controlled is the degree of curvature, which can be affected by acuteness of viewing angle.