Sensation Flashcards
(20 cards)
What do photoreceptors do?
Turn light wave energy into neural signals
List and describe the functions and location of the photoreceptors
Rods:
*Dim lighting
*sensitive to movement
*Found in Periphery
Cones:
*Good lighting
*Sensitive to colour and fine detail
*Found in fovea
Blindspot
*No photoreceptors
*Found in Optic Disc
How sensitive are we to light
About 400 - 700 nanoseconds of light
What happens at the Retina
Image is flipped upside down and backwards after being detected by photoreceptors
Define visual acuity, where is it most active?
*Ability to see fine detail
*The Fovea
What is the difference between Colour Contrast and Constancy
Colour Contrast states that perceived colour is influenced by the surroundings
On the other hand, Colour Constancy is the tendancy for a surface to appear as the same colour under different illuminants
What did Hubel and Weisel discover about the Primary Visual Cortex and cortical processing in the 1960’s
*The first stage of Cortical Processing involves the encoding of lines and edges, which the Visual Cortex will then organise
*The Cortical Cell is sensitive to orientation and responds strongly to vertically striped stimuli
What is Figure Ground Segregation in Holistic Perception?
The visual cortex will seperate figures from a background. This can be clear or unclear.
How does the visual cortex reconstruct a unified holistic perception
The brain puts together stimuli by using educated guesses about what’s likely to be true
These guesses are impacted by Gestalt Principles
What is a Gestalt Principles? List all four of the principles.
Rules for types of visual cues that are linked and grouped as a figure:
*Similarity
*Proximity
*Closure
*Continuity
Describe Perceptual Rivalry
When two interpretations of visual stimuli are equally plausible
How does the brain disambiguate perception
By using prior knowledge to overcome contradictory stimuli
Differentiate Monocular and Binocular depth cues
Monocular depth cues allow us to work out depth with one eye, whilst Binocular depth cues are more three-dimensional (3D)
What is a Linear Depth Cue
Parallel image in a 3D world will converge into 2D with distance
What is the Interposition Depth Cue
Focusses on depth order (when objects obstruct other objects)
What is the Relative Height Depth Cue
Below Horizon: Objects higher than the visual field appear to be further away
Above Horizon: Objects lower than the visual field appear to be further away
What is a Clarity Depth Cue
Suggests light is scattered across the atmosphere
What is the Relative Size Depth Cue
When comparing sizes between items without knowing the exact size of either, we assume the smaller objects are further than the larger objects
What is the Motion Parallax Depth Cue
Images closer to us move faster than further images as they pass
What is Binocular Disparity
Each eye has a slightly different view; we stare at the same object on the fovea of both eyes
There is a difference (disparity) in position for some surrounding objects, but not for others. This is used by the brain to build and perceive 3D images.
