Perception and the Senses
QOTD
Samantha Jacob, Eliza Granahan-field, Grant Vanek, Quinlyn Ambrose, Brady Goldsworthy
If you had to choose a sense to lose, which would it be?
a) vision
b) audition (hearing)
c) olfaction (smell)
d) gustation (taste)
e) touch
Hayley Park
Do you think that our individual perceptions are influenced by other aspects of our lives such as beliefs, memories, backgrounds, etc.?
A) yes
B) no
C) depends
Ryan Wolsky
The textbook mentions football players not feeling injuries until after a game due to anti-nociceptive signals. Have you ever had an experience such as this where you didn't realize the extent of your injury until well after it occurred?
A) yes
B) No
C) Can’t remember due to TBI
Mary Sarkisian
If you think about a taste will you trigger your senses and start to taste it?
a) yes
b) no
(next, replace taste -> smell)
Big Questions
How many megapixels are our eyes? How awesome are our other senses?
Sensation: the physical sensors
Is perception veridical, or just a convenient illusion? Is it a hard problem? How does it work?
Perception: internal encoding of sensory inputs into meaningful patterns
Illusions: reveal the tricks our brain uses..
Basic senses
Sense Stimulus Receptors
Psychophysics
Absolute threshold Lowest level of stimulus intensity for 50% response
Just-noticeable difference (JND) Difference in stimulus intensity for 50% response
We’ve got a pretty kick-ass set of senses!
How Many Megapixels??
• Retina has ~100 mega-rods, only ~5-7 mega-cones• Fovea can resolve about 30 cycles-per-degree (requires
cone spacing of ~.3 arcmin) = ~300 dpi at 10” (close!)• Focal length of human eye is ~22mm, max ISO about 800
Perception: Open Them Doors!
Dali!
How Does it Work?
1. Contrast, contrast, contrast Light/dark, color, time (adaptation) – just tell me the news!
2. Ass + u + me = visionary! The brain has to make many assumptions based
on “normal” visual inputs Easy to trick it with improbable coincidences..
Contrast Illusions
A = B??
No Way!
Contrast Illusions
A = B??
No Way!
Way!
Color Contrast
https://www.youtube.com/watch?v=gur-_IGV7F8
Time Contrast(we have a model of this)
Time Contrast
Ok Go!
https://www.youtube.com/watch?v=m86ae_e_ptU
Optic Pathway
Retinal Contrast Filtering
V1
25
Visual Hierarchy: What vs Where
26
27
Hierarchy of Detectors..
Each stage builds set of assumptions based on typical environmental input• Shape from shading• Depth cues: occlusion, texture, etc
Shape from Shading
Depth Cues
Depth Cues
3D!
Is Perception Veridical?
Perception is subjective So what does “veridical” mean? Cultural, language effects? Expectation effects?
Enter the Matrix..
The Chair Category
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