When Vision Gets It Wrong Flashcards
What is a blindsight?
Responding to stimuli in the blind part of the visual field under certain conditions.
What is hemianopias?
Loss of vision to the left or right side of fixation.
Damage to visual cortex.
What is agnosia?
Inability to recognise people/ objects even when basic sensory modalities are working.
What is visual agnosia?
Difficulty recognising objects faces and/or words
May show impaired object recognition with/ without impaired face and/or reading.
Cannot see objects but can interact with them
Auditory agnosia?
Inability to recognise sounds.
Somatosensory agnosia?
Difficulty perceiving objects through tactile stimulation.
What’s the dorsal stream?
Object localisation (where)
Guides actions
Smooth and efficient movements
What is the ventral stream?
Object identification (what)
Stored for future reference
Organises information
Can plan for future actions
What is a the bottom up illusion?
Physiological illusion- low level physiological mechanisms - sensory input
What is the top down illusion?
Cognitive illusion- constructivist.
Photoreceptors activated when light shines on it,
Inhibits firing of adjacent cells,
Increases contrast between 2 areas and helps detect edges.
The Herman grid:
Why do we see dark patches?
Intersection cells: more inhibition than cells elsewhere. Activates less seeming darker.
Foveate: cells in fovea have smaller receptive field. Illusion disappears.
Why do illusions occur?
The eye and visual system- bottom up illusions.
Eye uses knowledge about the world to convert a 2D image to a 3D image.
