PADM SUMMARY Perception
1. Perception I: vision
2. Perception II: faces/hearing
Perception I: Vision
→ elaboration and interpretation of a sensory stimulus
6 senses
Various receptors → thermoreceptors, prioriceptros, nociceptors, equilibrioception,
mechanoreceptors, stretch receptors, chemoreceptors, chrono receptors
Electromagnetic spectrum: what we perceive ≠ reality
- Humans view small fraction of electromagnetic spectrum (visible light)
- Other animals (honey bee) can view greater magnitude
- Given the same images, 2 species will view separately.
- Shows that reality is what we make of it
Eyes to the brain
- Left visual field → projects to right side of retina in both eyes → to right side of the
brain
- Right visual field → projects to left side of retina in both eyes → to left side of brain
Visual field → entire area that can be seen when an eye is fixed straight at a point.
Optic lens → converge or diverge light emitted from a peripheral object
Retina → senses light and creates electrical impulses
Optic nerve → transmits sensory information for vision in the form of electrical impulses from
the eye to the brain
,Optic chiasma → left and right optic nerves intersect at the chiasm (crossover), thus creating
the hallmark X-shape
Lateral geniculate nucleus (LGN) → a relay center in the thalamus for the visual pathway.
Primary visual cortex (V1) → Receives, integrates, and processes visual information relayed
from the retinas.
Split brain patients
- No corpus callosum
- Agenesis
- Necrosis “Machiafava Bignami”
- Colostomy (epilepsy treatment)
- No communication between right/left hemisphere (no crossover at the optic chiasma)
- Left side of brain → language
- Right side of brain → visual
Left visual field → right side of brain → picks up ring with left hand (same as visual field)
Right visual field → left side of brain → says ring
,Visual pathways of vision
- Primary: LGN → V1 (damage = blindness)
- Motor: LGN → V5 (damage = akinetopsia)
That is why people that are blind can still detect motion, as direct pathway runs to V5
Visual processing streams
- Dorsal “where” → spatial (damage = hemispatial neglect)
- Ventral “what” → Feature (damage = alexia/prosopagnosia)
Blindsight
- Damage to V1
- Patients that are blind can still detect motion (V5) → because a separate pathway of
LGN → V5 is responsible for motion.
Akinetopsia
- Patients with akinetopsia can sitl detect biological motion
Disorders of vision
Akinetopsia → inability to perceive motion (sees it as flashes instead)
Blindness → loss of vision
Alexia → failure to read words
Hemispatial neglect → after damage to one hemisphere of the brain is sustained, a
deficit in attention to and awareness of one side of the field of vision is observed
Prosopagnosia → failure to detect familiar faces (and onselesf)
Important brain parts
Suprachiasmatic nucleus (SCN) → in hypothalamus. Suppression of melatonin during day,
secretion of melatonin at night, regulates body clock/circadian rhythms, overcomes jet lag,
reduces blue spectrum of light (like night mode on phone)
Superior colliculus → head and eye movement
Posterior superior temporal sulcus (pSTS) → biological motion
, Visual cortices
________________________________________________________________________________________________________
Gestalt principles (mind perceives patterns)
a. Law of proximity → object close together belong together
b. Law of similarity → objects similar to each other belong together
1. Law of good continuation → see X rather than 2 lines
2. Law of closure → close circle
3. Law of common fate → objects that move together belong together
1. Perception I: vision
2. Perception II: faces/hearing
Perception I: Vision
→ elaboration and interpretation of a sensory stimulus
6 senses
Various receptors → thermoreceptors, prioriceptros, nociceptors, equilibrioception,
mechanoreceptors, stretch receptors, chemoreceptors, chrono receptors
Electromagnetic spectrum: what we perceive ≠ reality
- Humans view small fraction of electromagnetic spectrum (visible light)
- Other animals (honey bee) can view greater magnitude
- Given the same images, 2 species will view separately.
- Shows that reality is what we make of it
Eyes to the brain
- Left visual field → projects to right side of retina in both eyes → to right side of the
brain
- Right visual field → projects to left side of retina in both eyes → to left side of brain
Visual field → entire area that can be seen when an eye is fixed straight at a point.
Optic lens → converge or diverge light emitted from a peripheral object
Retina → senses light and creates electrical impulses
Optic nerve → transmits sensory information for vision in the form of electrical impulses from
the eye to the brain
,Optic chiasma → left and right optic nerves intersect at the chiasm (crossover), thus creating
the hallmark X-shape
Lateral geniculate nucleus (LGN) → a relay center in the thalamus for the visual pathway.
Primary visual cortex (V1) → Receives, integrates, and processes visual information relayed
from the retinas.
Split brain patients
- No corpus callosum
- Agenesis
- Necrosis “Machiafava Bignami”
- Colostomy (epilepsy treatment)
- No communication between right/left hemisphere (no crossover at the optic chiasma)
- Left side of brain → language
- Right side of brain → visual
Left visual field → right side of brain → picks up ring with left hand (same as visual field)
Right visual field → left side of brain → says ring
,Visual pathways of vision
- Primary: LGN → V1 (damage = blindness)
- Motor: LGN → V5 (damage = akinetopsia)
That is why people that are blind can still detect motion, as direct pathway runs to V5
Visual processing streams
- Dorsal “where” → spatial (damage = hemispatial neglect)
- Ventral “what” → Feature (damage = alexia/prosopagnosia)
Blindsight
- Damage to V1
- Patients that are blind can still detect motion (V5) → because a separate pathway of
LGN → V5 is responsible for motion.
Akinetopsia
- Patients with akinetopsia can sitl detect biological motion
Disorders of vision
Akinetopsia → inability to perceive motion (sees it as flashes instead)
Blindness → loss of vision
Alexia → failure to read words
Hemispatial neglect → after damage to one hemisphere of the brain is sustained, a
deficit in attention to and awareness of one side of the field of vision is observed
Prosopagnosia → failure to detect familiar faces (and onselesf)
Important brain parts
Suprachiasmatic nucleus (SCN) → in hypothalamus. Suppression of melatonin during day,
secretion of melatonin at night, regulates body clock/circadian rhythms, overcomes jet lag,
reduces blue spectrum of light (like night mode on phone)
Superior colliculus → head and eye movement
Posterior superior temporal sulcus (pSTS) → biological motion
, Visual cortices
________________________________________________________________________________________________________
Gestalt principles (mind perceives patterns)
a. Law of proximity → object close together belong together
b. Law of similarity → objects similar to each other belong together
1. Law of good continuation → see X rather than 2 lines
2. Law of closure → close circle
3. Law of common fate → objects that move together belong together
