Chapter 5- Sensation

Day 1

Sensation vs. Perception

lSensation: a process by which our sensory receptors and nervous system receive and represent stimulus energy

lSensation is the raw data our brain takes in from the environment.

lPerception: a process of organizing and interpreting sensory information, enabling us to recognize meaningful objects and events.

lPerception “makes sense” of sensation.

lExample: Prosopagnosia

Bottom Up vs. Top Down Processing

lBottom Up Processing: analysis that begins with the sense receptors and works up to the brain’s integration of sensory information.

l

lTop Down Processing: Information processing guided by higher-level mental processes

lAs when we construct perceptions drawing on our experience and expectations.

l

Psychophysics

lPsychophysics: study of the relationship between physical characteristics of stimuli and our psychological experience of them

lLight-

lSound-

lPressure-

lTaste-

Sensation: Thresholds

lAbsolute Threshold:

lUsually defined as the stimulus needed for detection 50% of the time.

“Subliminal Messages”

lSubliminal: information that is below one’s awareness for conscious attention

l

lDifference Threshold or (JND-Just Noticeable Difference): the minimum difference that a person can detect between two stimuli.

lWeber’s Law: to perceive a difference between two stimuli, they must differ by a constant proportion

llight intensity-

lweight-

ltone frequency-

lSignal Detection Theory: predicts how and when we detect the presence of a faint stimulus (signal) amid background stimulation (noise)

lAssumes that there is no single absolute threshold

Sensory Adaptation

lSensory Adaptation: diminished sensitivity with constant stimulation.

The Science of Energy and Sensation

lTransduction-

lWavelength-

lHue-

lIntensity-

lbrightness

lloudness

Day 2

Sense 1- vision

Biology of Vision Step One: Light Enters the Eye

1.)  Light enters the eye through the ______: (transparent protector) and the light passes through the ______: (small opening/hole). The size of the opening (pupil) is regulated by the ______: the colored portion of your eye that is a muscular tissue which widens or constricts the pupil causing either more or less light to get in.

Biology of Vision Step Two: An Image is Produced

2.)  Behind the pupil, the ______, a transparent structure, changes its curvature in a process called ______, and focuses the light rays into an image on the light-sensitive back surface called the ______: where image is focuses.

Biology of Vision Step Three: Chemical Reactions and Sight

3.)  Image coming through activates photoreceptors in the retina called ______. As rods and cones set off chemical reactions they form a synapse with ______which forms a synapse with ______which fire action potentials along the ______: that carries this information to be processed by the ______: (sensory switchboard) that sends information to the ______which resides in the ______. The brain then constructs what you are seeing and turns image right side up.

Parts of Retina

lBlind Spot: part of retina where optic nerve leaves the eye…no receptor cells are there.

lFovea: central focal point of the retina, where cones cluster.

lCones: located near center of retina (fovea)

lfine detail and color vision

lRods: located near peripheral retina

ldetect black, white and gray

Errors In Vision

lAcuity:

lNearsightedness:

lnearby objects seen more clearly

lFarsightedness:

lfaraway objects seen more clearly

Visual Involves Parallel Processing

lParallel vs. Serial: parallel means simultaneous while serial means step by step. Our brains process are often parallel processes while computers work serially.

lParallel Processing: simultaneous processing of several dimensions through multiple pathways. Different part of brain for:

Parallel Processing

lFeature Detectors: neurons in the visual cortex respond to specific features

Visual Information Processing

lTrichromatic (three color) Theory

lYoung and Helmholtz

lthree different retinal color receptors

Color Deficient Syndrome

People who suffer red-green blindness have trouble perceiving the number within the design

Opponent-Process Theory- opposing retinal processes enable color vision.

Color Constancy

lHuman Beings maintain Color Constancy: perceiving familiar objects as having consistent color, even if lighting changes to alter the wavelength given off by the object.

Context Affects Color

lWe only retain color constancy when the context remains the same.

lSame color will look different when compared in different contexts.

Day 3

Sense 2: Hearing (Audition)

The loudness of a sound is determined by a waves amplitude (height.)

The frequency, number of complete wavelengths that pass a point in a given time, determines the sounds pitch:

Hearing Threshold

Hearing is measured in decibels.

Parts of the Ear

Outer Ear:

Job:

Parts: auditory canal and eardrum.

Middle Ear

Job:

Parts: Ossicles, made up of three tiny bones: hammer, anvil, and stirrup (malleus, incus, and stapes)

Inner Ear

Job:

Parts: Oval Window, Cochlea, Basilar Membrane, Hair Cells.

Process of Hearing

1.Your ______.

2.Your ______with sound waves

3.This causes ______(the hammer, anvil and the stirrup) ______

4. ______. The cochlea is fluid filled and ______.

5. Inside the cochlea is a ______and are transduced into a ______

6. Hair cells synapse with ______

7. The auditory nerve transmits sound messages though your ______

______

Inner Ear and Vestibular Sense

The semicircular canals are connected to the cochlea by the vestibular sacs.

The semicircular canals contain substance that move when our head rotates or tilts and allows us to maintain our vestibular sense.

How Do We Perceive Pitch: 2 Theories

Hemholtz’s Place Theory: argues we hear different pitches because different sound waves trigger activity at different places in the cochlea’s membrane

Frequency Theory: We sense pitch by the basilar membrane in cochlea vibrating at the same rate as the sound. Explains low pitch well….

Volley Principle-

Parallel Processing

Just like with vision, audition involves parallel processing

Hearing Loss

Conductive Hearing Loss: hearing loss caused by damage to the mechanical system that conducts sound waves to the cochlea like eardrum and ossicles.

 Sensorineural Hearing Loss: damage caused to cochlea’s receptor cells (hair cells) or auditory nerves.

Day 4

Sense 3-Touch

Premature Babies

Monkeys

 Skin sensations are a variation of the basic 4

Pain Is a Good Thing!

Gate Control Theory:

Social Influence On Pain

-Pain is both a physiological and a psychological phenomenon.

-Depending on symptoms, doctors may use drugs, surgery, etc. or relaxation training, thought distraction.

Example:

Memories of Pain

More to our memories of pain than the pain we experienced.

People tend to overlook duration of pain and instead concentrate on its peak moments and how much pain they felt at the end.

Sense 4-Taste

4 Basic Sensations

Sweet

Sour

Salty

Bitter

Taste and Smell

Taste and Smell are both chemical senses.

Tongue is central muscle for taste which contain taste buds.

Smell runs through receptor cells in nasal cavity which are send neural signals to the olfactory bulbs in the brain.

Sense 5-Smell

5 million receptor cells at the top of your nasal cavity

Detect 10,000 odors

Decreases with age

 Nasal Cavity brings the smell up to your receptors

Receptor cells send the message to the brain’s olfactory bulb,then to the temporal lobe’s primary smell cortex

Smell and Emotion

Sense of smell activates areas in limbic system involved in emotion and memory.

Smells can often evoke memories of the past or emotional experiences more often than most other senses.

Sensory Restriction

People born without access to a sense, compensate with development of stronger other senses.

Sensory Restriction has produced mixed results depending on context:

4.) 

5.) 

6.)