Sensation and Perception

Pitch

Volume

Parts of the Ear

Dr. Caitlin O’Conell

• Namibia

• Studies Elephants

• communications done in calls of high and low pitch

  • 2 km long distance communication

• Elephants detect sound through their ears and the ground though the trunk and feet - vibrotactile sense

• Experiment with speaker and shaker

  • Elephants leave quicker with speaker but did respond to the shaker as well

What is sensation?

The collection of raw energies by specific sensitive cells

Parapsychology - extrasensory perception

Sensing something outside of our senses

EMR

Energy waves that vary in wavelength and vary in intensity

Visible Light Spectrum

• 400-700 nm wavelengths

• the higher the number, the higher the frequency and the shorter the wavelength

Properties of Light

• Wavelengths

• Peak

• Amplitudes

• Trough

• Purity - the extent to which the light sources contains different wave signatures

• full spectrum light or white light is the combination of many wave signatures

• single wavelength are only in lasers

Sensation vs. Perception

• wavelength → color

• amplitude → brightness

• Purity → saturation

Length and Color

• 700 nm Dark Red

• 665 Red

• 630 orange

• 600 yellow

• 550 green

• 490 aqua

• 470 blue

• 470 blue

The shorter the wavelength

The higher the energy

Cornea

refracts light; is clear

Pupil

emits light; can change in size to admit more or less light

Iris

Colored muscles around the eye

Sclera

Whites of the eyes; protective function; boundary between the eyeball and all else

The lens

• sits behind pupil

• disc-shape

• accommodates the light to hit the back of the eye (fovea)

Retina

• photosensitive

• lines the interior of the eyeball

• as thick as a sheet of paper

• Fovea is a specialized spot in the retina

Blind Spot

• Optic nerve

• No retina

• No sensation there

• Why we don’t see from our blind spot

  • Overlap of eyes

  • time lag

  • educated guesses

Rods

• low-light conditions

• we have lots of these

• gross movement

• little detail

• periphery

• no color info

• 20x more rods than cones

• Higher convergence compared to cones

Cones

• Active in bright light

• Color

• Details

• Preferred wavelengths

• 12 million shades of color

transduce

to turn an input into electrical energy

• all cells in sensory systems have to be able to transduce energy

Two visual paths behind the eye (1)

• 10% of data from each eye is used for unconscious vision and space

  • optic nerve → superior colliculus (processes electrical signal) → parietal lobe

Two visual paths behind the eye (2)

• 90% of conscious vision, processing, recognition, and faces

• optic nerve → thalamus → occipital lobe → parietal

  • recognize where something is

• optic nerve → thalamus → occipital lobe → temporal

  • recognize what something is

Neuron Speeds

• faster than usual

• default

• slower than usual

Coding

• 1-1 correspondence between physical stimulus and neurons and system activity

Feature Analysis

• One theory of how we assemble forms

• process of detecting specific elements in visual input and assembling them into a more complex form