Week 2 Flashcards
Aristotle’s five senses
Touch, sight, smell, taste, hearing
-Separate module for each sense
Not a comprehensive list of all senses, e.g missing temperature, balance, ect
Sense modalities:
Olfactory
Smell: food, pheromones, danger, ect
Sense modalities:
Somatosensory
Touch: heat, position, pain, ect
Sense modalities:
Auditory
Sound: words, threats, direction of noise ect
Sense modalities:
Visual
Sight: objects, faces, reading
Perception
Conscious high level processing of sensory information typically carried out in the prefrontal cortex
Sensation
The automatic collection of sensory information coded through sensory organs
Information Processing Approach
Information is processed in sequential stages passing information to different parts of the brain. E.g:
Sensory information (input) -> Mental operations (processing) -> Perception (output)
Sensory system organisation
Hierarchical Organisation- information processed through least to most complex systems
Functional Segregation- different analysis specialisms
Parallel Processing- processed in multiple systems at once (used to be considered serial processed but model changed to parallel)
Human eye structure:
Cornea
The protective layer at the front of the eye
Human eye structure:
Iris
The ring around the pupil which contracts and dilates to control light input
Human eye structure:
Pupil
The gap in the iris which allows light into the eye, allowing us to see objects
Human eye structure:
Lens
The clear layer behind the pupil which changes shape depending on the distance from the object we are looking at, to bend the light so it hits the retina in the right place
Human eye structure:
Retina
The light sensitive nerves which receive the light reflected off of objects
Human eye structure:
Optic nerve
Carries signals from the retina to the brain
Human eye structure:
Blind spot
The area where the optic nerve connects to the retina, creating a blind spot which cannot receive sensory information
Human eye structure:
Fova
A depression in the retina where visual information is received most accurately
Human eye structure:
Sclera
The whites of the eye
Human eye structure:
Ciliary muscles
Control movement of pupil and lens
Light & Visual perception
We can only see the visible light spectrum. Sunlight contains all colours in the visible light spectrum (Violet, Indigo, Blue, Green, Yellow, Orange, Red). Objects absorbs all light colours except for the colours they are. E.g. Red objects reflect red light and absorb all other colours, we perceive the object as red as that is the light reflected into our eyes.
Eye position dispartity
Animals have eyes in different places depending on purpose e.g. reptiles and prey have eyes further apart to expand their field of vision while predators have eyes as the front for better vision of details and depth
Binocular disparity
The eyes each have a slightly different perspective, allowing the brain to combine these images to perceive depth
Eye movement:
Fixations
The points which our eye movements briefly stop on (3 per second)
Eye movement:
Saccades
The rapid movements between fixations, needed as visual neurons respond to change rather than consistent input
Eye movement:
Stabilized retinal images
Static imagine inputs in our visual neurons cause the image to disappear
Eye movement:
Temporal integration
The integration of fixations allowing us to see details, and stopping images disappearing when we blink.
Duplexity theory
The retina contains rods and cones, which are thought to help with different types of vision e.g. cones for photobic (bright light) vision & focus in the fovea while rods are for scotopic (low light) vision & are mostly in our peripheral
Visual areas of the cortex
Posterior partial cortex
Prestraite cortex
Primary visual cortex
Inferotemporal cortex
Dorsal vs Ventrical stream
Both receive information from primary visual cortex
-Dorsal (top) originally thought to be “where” path but now thought to be behavioural control pathway
-Ventral (bottom) stream originally thought to be “what” path, now thought to be conscious perception pathway
Prosopagnosia
Inability to recognise faces, may not be specific to faces, caused by in the fusiform face area
Damage to the primary visual cortex
Damage causes scotomas (blind spots) which are plotted using perimity tests
Blind sight is when patients can respond to stimuli in their scotomas
Gestalt’s Laws:
Law of Proximity
Objects close together are grouped
Gestalt’s Laws:
Law of Similarity
Similar objects grouped
Gestalt’s Laws:
Law of Symmetry
Symmetrical objects are grouped
Gestalt’s Laws:
Law of Contiuations
Aligned objects perceived as one entity
Gestalt’s Laws:
Law of Proximity
Objects close together are grouped
Ambiguity
Causes multi-stable perception (images can be perceived in different/ changing ways)
Depth perception
Enabled by binocular disparity, can detect absolute distance (distance from observer to object) and relative distance (distance between two objects)
Cues:
Monocular cues
-Texture gradients
-Relative size
-Interposition (objects obscuring other objects)
-Linear perspective (parallels appearing to converge towards horizon
-Aerial perspective (closer images clearer)
-Location in picture plane (higher objects seem further)
-Motion parallax (closer objects appear faster)
-Further colours appear bluer
Cues:
Binocular cues
Level of disparity interpreted as cue of depth, becomes less effective the greater the distance
Influence of context
Context can make objects appear different to their actual size
Global processing
Processing the parts of an image as a whole rather than focusing on individual details
Local processing
Processing the parts of an image separately rather than as one entity
