partb Flashcards
(23 cards)
sensation
the process by which our sensory receptors and sense organs DETECT AND RESPOND to sensory information that stimulates them. “raw information”
Perception
the process by which we GIVE MEANING to sensory information “give meaning to information”
- differences between sensation and perception
sensation:
- detect and respond to info
- passive process
- involves the sense organs and related structures
- is a physical process
perception:
-apply meaning to info
- active process
- involves the brain
- is predominantly a psychological process (but can also be physical)
visual perception factors
- Visual Perception Factors = ‘Rules’ that we apply to visual information to assist our organisation and interpretation of the information in consistent and meaningful ways.
- These help us to ‘make sense’ of visual information that is sometimes inconsistent or incomplete.
- We tend to automatically use these factors, without any conscious effort or awareness that we are doing so.
Depth Perception
- Depth Perception is the ability to accurately estimate the distance of objects and therefore perceive the world in three dimensions.
Depth Cues
- Depth cues are sources of information from the environment (external cues) or from within our body (internal cues) that help us perceive how far away objects are.
diff between binocular and monocular
- depth cues that are binocular require two eyes and monocular require one eye
binocular depth cues?
-convergence
- retinal disparity
monocular depth cues?
- accomodation
- linear perspective
-interposition - texture gradient
- relative size
- height in the visual field
(binocular) convergence?
-Convergence is a visual perception depth cue involving the inwards turning of the eyes to focus on nearby objects.
The brain detects depth by how much tension is in the eye muscles as they turn the eyes inward.
-Only really good for detecting distance
within approx. 6 metres.
- From about 6 metres outwards there is
little to no difference in convergence of
the eyes = other depths perception cues
need to be used.
(binocular) retinal disparity?
- Retinal disparity is a visual depth cue based on the difference/disparity of the retinal images.
-The brain compares the images and the disparity from both retinas and is then able to judge depth/distance - Again, the binocular cue in this case is only good for perceiving depth of objects that are relatively close = there is little retinal disparity beyond approx. 10 metres.
- Other depth cues are required for perceiving depth over long distances.
(monocular) accommodation
- Accommodation (in visual perception) is a depth cue involving the automatic focusing of the lens in the eye in response to changes in distance of view from an object.
-Brain perceives distance based on the ciliary muscles (which control the lens shape) contracting (lens bulging) and expanding (lens flattening)
(monocular) linear perspective
- Linear perspective is the apparent convergence of parallel lines as they recede into the distance.
(monocular) Interpostion
- Interposition (overlap) is when one object partially blocks or covers another, and the partially covered object is perceived as further away.
(monocular) texture gradient
- Texture gradient refers to the gradual reduction of detail in a surface as it recedes into the distance (as compared with the fine detail of a close up surface).
(monocular) relative size
- Relative size refers to the tendency to visually perceive the object that produces the largest image on the retina as being closer, and the objects that produces the smaller image as being further away.
(monocular) height in the visual field
- 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.
gestalt principles
- Refers to the numerous ways in which we organise features of a visual scene to perceive a whole, complete form, usually in the simplest way
- the whole is greater than the sum
Figure ground
- Organise visual information by perceptually separating important aspects of the visual field into the ‘figure’ which stands out from the ‘ground’ (surroundings).
- Figure ground organisation is generally achieved by the observer separating the figure from the ground using an existing line (actual) or perceived (inferred) line. The line of separation between figure and ground is known as the CONTOUR. The contour is always perceived as belonging to the figure.
Figure ground facts
- There are cultural differences in the use of figure-ground.
- Westerners tend to focus on single objects in foreground (figure)
- Easterners tend to focus on the entire scene rather than specific features.
closure
- Perceptual tendency to mentally close up, fill in, or ignore gaps in a visual stimulus and to perceive objects as complete.
- The perceptual tendency to close up, fill in or ignore gaps in sensory input and perceive objects as complete.
- Our minds react to patterns that are familiar, even though we often receive incomplete information. As a result, we tend to perceive an object as ‘whole’ despite it actually being incomplete.
-The principle of closure is evident in our perception of many ;logos and especially in the work of cartoonists.
similarity
- The tendency to perceive that parts of a stimulus which have similar features, such as size, shape, texture or colour, as belonging together in a unit or whole.
proximity )aka nearness)
- The tendency to perceive parts of a visual stimulus which are positioned close together as belonging together in a group, as a whole.
Note that similarity tends to override proximity when the two principles co-exist.
