Lecture 6 - Perception 2 Flashcards
What is Depth Perception?
The ability to locate identified forms in space - specifically, it allows us to see objects in three dimensions and judge distance.
What cues does Depth Perception use?
Binocular cues (require the use of both eyes), and Monocular cues (require the use of one eye)
What are Binocular cues used for?
Primarily used for objects very close to the perceiver - there are two main binocular cues (retinal disparity and convergence)
What is Retinal Disparity/Stereopsis?
When images from the two eyes differ - the closer the object the larger the disparity - e.g. when an object appears closer to the right eye then it does to the left eye
What is Convergence?
A neuromuscular cue - the two eyes move inward for nearer objects. Lowest convergence is furthest away, highest convergence is very close - crosseyed.
What are monocular cues used for?
Distant and depth - there are many monocular cues
What monocular cues are there?
Relative size, interposition, linear perspective, relative clarity, texture, relative height, relative brightness, relative motion, and motion parallax.
What is Relative Size?
The smaller image is further away, while larger images are closer.
What is Interposition?
Closer objects block more distant objects.
What is Linear Perspective?
Parallel lines converge with distance - appear to get closer together the further away they go.
What is Relative Clarity?
Clearer objects seem closer - less clear objects seem more distant.
The clearer an object is the closer it seems.
What is Texture?
Coarser objects seem closer, while finer objects seem more distant.
More texture can be perceived closer, and less farther away.
What is Relative Height?
Higher objects are seen as more distant, while shorter objects are seen as closer.
What is Relative Brightness?
Closer objects appear brighter, and further objects seem darker - BUT your visual system will tend to equalise the brightness.
What is Relative Motion?
Closer objects seem to move faster - because distant objects can be seen for longer so SEEM slower.
What is Motion Parallax?
The change of position of two stationary points relative to each other as seen by an observer caused by the motion of an observer.
By moving and changing YOUR perspective, the focus of your vision seems to move.
Explain constancies in visual perception
The light that hits our eyes results in quite a diverse range of patterns on our retinas - but, our experience is of relatively stable perceptions. The forms in the world around us change much more than we are aware of, but our visual system expects certain changes in the light that hits our eyes from the
same objects
What is Brightness Constancy?
Our visual system adjusts to variations in
light very well, e.g. Even though a grey sheet of paper may reflect more light on a sunny day than a white sheet on a cloudy day, we still see the grey sheet as grey and the white sheet as white
Our visual system works on the relative brightness of the object
What is Size Constancy?
We expect the context within which we judge the size of an object not to change - if it does we can be tricked by perspective
What is Form Constancy?
The same shape can look different from different angles and yet we experience a consistent perception - e.g. if we see a square from different angles its still recognisable as a square
