Unit 5- Sensation and Perception

Sensation: your window to the world

Perception: interpreting what comes in your window

SENSATION: the process by which our sensory receptors and nervous system receive stimulus from the environment.

Concepts....

1. Bottom-up Processing: begins with the sense receptors and works up to the brain's integration of sensory information.

2. Top-down Processing: information processing guided by higher level mental processes.

Absolute Threshold: the minimum stimulation needed to detect a stimulation needed to detect a stimulus 50% of the time.

Difference Threshold: the minimum difference that a person can detect between two stimuli.

Weber's Law: the idea that, to perceive a difference between two stimuli, they must differ by a constant percentage, not a constant.

Signal Detection Theory: predicts how we detect a stimulus amid other stimuli.

Sensory Adaptation: decreased responsiveness to stimuli due to constant stimulation

Selective Attention: the focusing of conscious awareness on a particular stimulus.

Cocktail Party Phenomenon: cocktail party effect describes the ability to focus on ones listening attention on a single talker among a mixture of conversations and background noises... Ignoring other conversations.

Energy Vs. Chemical Senses:

Vision: our most dominating sense.

• The height of a wave gives us intensity (brightness)
• The length of the wave gives us its hue (color)
• ROY G BIV
• The longer the wave, the more red it is. 
• The shorter the wavelength, the more violet.

Transduction: transforming signals into neural impulses.... Transduction in the ear is when sound waves hit the eardrum then anvil then hammer then stirrup then oval window. 

Young-Helmholtz Theory:

Three types of cones...

1. Red
2. Blue 
3. Green

-You can make millions of combinations of colors with these 3 primary colors.

Opponent Process Theory: sensory receptors come in pairs.

• Red and Green
• Blue and Yellow
• Black and White

If one color is stimulated, the other color in inhibited.

Sound

Important words when it comes to sound....

Amplitude and Wavelength

-The height of the wave gives us the amplitude.

-The longer the wavelength, the lower the pitch and vice versa.

Transduction in the ear

-Sound waves hit the eardrum, then the anvil, then the hammer, then the stirrup, then the oval window.

-The cochlea is lined with mucus called basilar membrane.

-In the basilar membrane, there are hair cells. 

-When hair vibrates, the vibrations turn into neural impulses which are called Organ of Corti.

-Sent to thalamus up auditory nerve.

Pitch Theories

1. Place Theory: different hairs vibrate in the cochlea when there are different pitches, so some hairs vibrate when they hear high pitches.
2. Frequency Theory: all the hairs vibrate at different speed.

Deafness

1. Conduction Deafness: something goes wrong with the sound and the vibration is on its way to the cochlea.
2. Nerve (sensorineural) Deafness: hair cells in cochlea get damaged.

Causes of deafness...

• loud noise
• no way to replace hairs
• cochlea implant is possible

Why do we study smell and taste together??????

Sensory Interaction: the principle that one sense may influence another.

Taste

-We have bumps on our tongue called papillae.

-Taste buds are located on the papille (all over the mouth actually)

(picture of sweet salty bitter blah blah blah)

Touch

• receptors located in our skin.

Gate control theory of pain: the spinal cord contains a neurological gate that contains blocked signals or allows them to pass onto the brain.

Vestibular Sense: tells us where our body is oriented in space

-Our sense of balance

Kinestetic Sense: tells us where our body parts are

-Receptors located in our muscles and joints

PERCEPTION: The process of organizing and interpreting information, enabling us to recognize meaningful objects and events.

Gestalt Philosophy: the whole is greater than the sums of its parts.

Figure Ground Relationship: the organization of the visual field into objects (figures) that stand out from their surroundings.

Grouping: the perceptual tendency to organize stimuli into groups that we undersand.

• Proximity:
• Similarity:
• Continuity:
• Connectedness: 

Depth Perception: the ability to see objects in 3 dimensions although the images that astrike the retina are two dimensional.

• Allows us to judge distance

Visual Cliff: not being aware of how far down

Binocular Cues

Retinal Disparity: a binocular cue for seeing depth. The closer an object comes to you, the greater the disparity is between the two images.