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