Visual Perception Flashcards
What is sensation?
The bottom up process by which our senses like vision, hearing and smell, receive and relay outside stimuli. (PHYSIOLOGICAL) The three stages are: *Reception *Transduction *Transmission
What is perception?
The top down way our brains organise and interpret specific information and put it into context. (PHYSIOLOGICAL and PSYCHOLOGICAL) The three stages are: *Selection *Organisation *Interpretation
What is the absolute threshold of sensation?
The minimum stimulation needed to register a particular stimulus under ideal conditions fifty percent of the time.
What is the differential threshold?
The smallest difference in the amount of a given stimulus that a specific sense can detect.
Rods
- Black and white vision
- Peripheral vision
- They have low visual acquity (can’t register detail)
- Concentrated at the edges of retina
Cones
- Concentrated in the middle of the retina (fovea)
- Responsible for vision of detail
- Responsible for colour vision and black and white vision in daytime
- Require high levels of light to enable them to respond
Reception
The collection of light by the eye and focusing it on the retina, which contains the photoreceptors (light-sensitive cells) called rods and cones.
Transduction
Conversion of electromagnetic energy (light energy) into electrochemical energy (or nerve mpulses) by photoreceptors (rods and cones).
Transmission
Transmission of neural impulses along the optic nerve to the primary visual cortex in the back of the brain.
Selection
Selection of features of a stimulus by specialised neurons in the visual cortex called feature detectors.
Organisation
Visual information reaching the brain’s visual cortex is reorganized using perceptual principles (perceptual constancies, Gestalt principles, depth cues).
Interpretation
The brain’s temporal lobes identify the object by comparing incoming information already stored in memory (perceptual set), and the parietal lobes assist in judging where the object is in space.
Monocular Depth Cue
Information about depth available in just one eye’s view.
Binocular Depth Cue
Requires both eyes to work together to provide information about depth and distance.
What are the two types of monocular depth cues?
Accommodation
Pictorial Depth Cues
Types of pictorial depth cues?
Linear Perspective
Interposition (overlap)
Texture Gradients
Relative Size
Height in the visual field
Linear Perspective
Parallel lines that appear to converge as they extend towards an imaginary point.
Interposition
When one object partially blocks another; the partially blocked object is perceived as further away.
Texture Gradient
Gradual reduction of detail that occurs in a surface as it recedes into the distance.
Height in the visual field
Objects that are closer to the horizon are perceived as further away.
What is perceptual constancy and what is it useful for?
- Recognising familiar objects as having standard shape, size, colour, or location - regardless of changes in the angle of perspective, distance, or lighting.
- Helps us identify objects under various conditions.
Types of perceptual constancies?
Size constancy
Shape constancy
Brightness constancy
Orientation constancy
Size constancy
Recognising that an object’s actual size remains the same even though it changes on your retina.
Shape constancy
Regardless of angle, we tend to perceive an object as maintaining its shape.
Brightness constancy
Tendency to perceive an object as maintaining its level of brightness in relation to its surroundings despite changes in the amount of light.
Orientation constancy
When you perceive the object as being the same regardless of the orientation.
What is the perceptual set?
- Stresses the idea of perception as an active process involving selection, organisation (inference) and interpretation.
- Stimuli is perceived in a specific way for each individual
What does the perceptual set include?
Previous experience
Context
Motivation
Emotion