Visual perception principles

1. Visual perception principles By Andrea Rees

2. Visual perception principles • Are rules that we apply to visual information to assist our organisation and interpretation of the information in consistent and meaningful ways.

3. Gestalt principles • Refer to the ways in which we organise the features of a visual scene by grouping them to perceive a whole, complete form.

4. Figure-ground organisation. • When we use figure-ground, we organise visual information by perceptually dividing a visual scene into a ‘figure’, which stands out from the ‘ground’, which is it’s surroundings. • Figure ground organisation is generally achieved when we separate the figure from the groundusing a line or boundary between the figure and the ground, which may or may not exist in the scene. This line of separation between the figure and ground is known as a contour.

5. Closure • Closure refers to the perceptual tendency to mentally ‘close up’, fill in or ignore gaps in a visual image and to perceive object as complete (‘whole’).

6. Proximity • The principle of proximity (or nearness) is the tendency to perceive parts of a visual images which are positioned close together as belonging together in a group.

7. Depth principles • Depth perception is the ability to accurately estimate the distance of objects and therefore perceive the world in three dimensions.

8. Depth cues • Sources of information from the environment (external cues) orfrom within our body (internal cues) that help us to perceive how far away objects are and therefore to perceive depth. • Depth cues can be categorised into two groups- binocular (requiring the use of both eyes) or monocular (requiring the use of only one eye).

9. Binocular depth cues • Require the use of both eyes working together in order to provide information to the brain about depth and distance.

10. Convergence • Involves the brain detecting and interpreting depth or distance from changes in tension in the eye muscles that occur when the two eyes turn inwards to focus on objects that are close.

11. Retinal disparity • Refers to the very slight difference (‘disparity’) in the location of the visual images on the retina (due to their slightly different angles of views) which enables us to make judgements about the depth or distance of an object.

12. Monocular depth cues • Require the use of only one eye to provide information to the brain about depth and distance, but they also operate with both eyes. • They include accommodation and pictorial cues such as linear perspective, interposition, texture gradient, relative size and height in the visual field.

13. Accommodation • Involves the automatic adjustment of the shape of the lens to focus an object in response to changes in how far away the object is.

14. Pictorial cues • Pictorial cues are named because artists use them to create depth and distance on two dimensional surfaces such as paper and canvas.

15. Linear perspective • Is the apparent convergence of parallel lines as they recede (‘go back’) into the distance.

16. interposition • Or overlap as it is also called, occurs when one object partially blocks or covers another, and the partially blocked object is perceived as further away than the object that obscures it (and vice versa).

17. Texture gradient • Refers to the gradual reduction of detail that occurs in a surface as it recedes into the distance, compared with a surface that is close and perceived in fine detail.

18. Relative size • Refers to the tendency to visually perceive the object that produces the largest image on the retina as being closer, and the object that produces the smallest image on the retina as being further away.

19. Height in the visual field • Refers to the location of objects in our field of vision, whereby objects that are located closer to the horizon are perceived as being more distant than objects located further from the horizon. Horizon Object that appears more distant

20. The end. • Thank-you for reading.  A+