Sensation Group(Bay-ag, Evangelista, Lafuente, Marquez, Ramones, Sueltp)! ! 1Psychology-6 ! Sensation is the stimulation of a sensory receptor which produces neural impulses that the brain interprets as a sound, visual image, odor, taste, pain, etc. Sensation occurs when sensory organs absorb energy from a physical stimulus in the environment. Sensory receptors then convert this energy into neural impulses and send them to the brain. The nervous system is responsible for sensing the external and internal environments of an organism, and for inducing muscle movement. Human sensation is achieved through the stimulation of specialized neurons, organized into five different modalities—touch, balance, taste, smell, hearing, and vision. Transduction and adaptation are some characteristics of sense organs.

Sensations can be defined as the passive process of bringing information from the outside world into the body and to the brain. The process is passive in the sense that we do not have to be consciously engaging in a "sensing" process.Perception can be defined as the active process of selecting, organizing, and interpreting the information brought to the brain by the senses.

A) How sensation works

1) Sensation occurs: a) sensory organs absorb energy from a physical stimulus in the environment. b) sensory receptors convert this energy into neural impulses and send them to the brain.

THE SENSE OF VISION Stimulus: Light Waves

Visible Spectrum – is one particular segment of the electromagnetic energy that we can see because these waves are the right length to stimulate receptors in the eye.

Structure and Functions:

1. Image and Reversed

2. Light Waves

3. Cornea – is the rounded, transparent covering over the front of your eye.

4. Pupil – is a round opening at the front of your eye that allows light waves to pass into the eye’s interior

5. Iris – is a circular muscle that surrounds the pupil and controls the amount of light entering the eye.

6. Lens – is a transparent, oval structure whose curved surface bends and focuses light waves into an even narrower beam.

7. Retina – is a thin film that contains cells that are extremely sensitive to light.

Light-sensitive cells, called photoreceptors, begin the process of transduction by absorbing light waves.

Eyeball’s Shape & Laser Eye Surgery:

Some of us are born w/ perfectly-shaped eyeballs, which contribute to having almost perfect vision.

• Normal Vision

• Near-sighted(Near-sightedness/Myopia)

-is a vision condition in which close objects are seen clearly, but objects farther away appear blurred. Near-sightedness occurs if the eyeball is too long or the cornea, the clear front cover of the eye, has too much curvature. As a result, the light entering the eye isn’t focused correctly and distant objects look blurred.

• Far-sighted(Far-sightedness/Hyperopia)

-is a vision condition in which distant objects are usually seen clearly, but close ones do not come into proper focus.

Sensation Group(Bay-ag, Evangelista, Lafuente, Marquez, Ramones, Sueltp)! 1Psychology-6-Far-sightedness occurs if your eyeball is

too short or the cornea has too little curvature, so light entering your eye is not focused correctly.

The Retina

1. Rods – are photoreceptors that contain a single chemical called Rhodopsin, which activated by small amounts of light.

Cones – are photoreceptors that contain three chemical opsins, which are activated in bright light and allow us to see color.

2. Transduction – the process which begins when chemicals in the rods and cones break down after absorbing light waves

3. Nerve Impulses

The Visual Pathways: Eye to Brain

1. Optic Nerve

2. Primary Visual Cortex

3. Visual Association Areas

Trichromatic Theory

-Says that there are three different kinds of cones in the retina, and each cone contains one of three different light-sensitive chemicals, called opsins.

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Opponent-process Theory

-Afterimage is a visual sensation that continues after the original stimulus is removed.

-States that Ganglion cells in the retina and cells in the thalamus of the brain respond to two pairs of colors: red-green and blue-yellow. When these cells are excited, they respond to one color of the pair; when inhibited, they respond to the complimentary pair.

Color Blindness

-Is the inability to distinguish two or more shades in the color spectrum.

Kinds of Color Blindness:

A. Monochromats – have total color blindness; their worlds look like black-and-white movies. This kind of color blindness is rare and results from individuals having only rods or only one kind of functioning cone instead of three.

B. Dichromats – Usually have trouble distinguishing red from green because they just have two kinds of cones. This is an inherited genetic defect, found mostly in males. This results in seeing mostly shades of blue and yellow.

THE AUDITORY SENSE

The Auditory or Audition sensation is what we use in order to hear. It uses transduction, which transforms vibrations into electric signals, to gather information from sound waves, the stimuli for hearing. The waves are represented by ripples and its parts are used to identify a sound’s loudness and pitch. Amplitude is what we call the distance from the top to bottom of a sound wave, while frequency is the measurement of sound waves happening in one second.

Amplitude, if higher, is represented as louder sounds. Meanwhile, when a sound wave is more frequent, it is a high pitched sound. This is shown on the lower part of the photo, and an example of this is a person shouting. The upper part shows a softer, less frequent sound, like a person whispering.

Decibels are what we call the measurement of loudness, which ranges from 0 dB to 140 dB. The colors show how long it would take before a sound would cause hearing loss. It would take listening to an 80 dB for 8 hours, a 100 dB sound for 2 hours, or a 120 dB sound for 15 minutes to make a person deaf.

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Sensation Group(Bay-ag, Evangelista, Lafuente, Marquez, Ramones, Sueltp)! ! 1Psychology-6 The outer ear’s shape is used for gathering nearby sound waves. The oval structure is called the pinna. It connects to a narrow, long tube called the ear or auditory canal. At the end of the canal is the inner ear, made up of the eardrum or tympanic membrane, and the ossicles. These are three small bones in order are called the hammer, anvil, and stirrup. When sound waves enter, the eardrum vibrates and passes it to the ossicles, amplifying the sound in the process.

The amplified sounds are then passed on to the oval window in the inner ear. The inner ear is composed of the cochlea and the semicircular canals. The cochlea, which looks like a snail’s shell, is

the part which transduces the vibrations into electric signals and contains the hair cells. The hair cells, or auditory receptors, are located near the cochlea’s lower membrane, known as the basilar membrane. When fluids in the cochleal tube vibrate, the basilar membrane starts to move and bend the hair cells, generating nerve impulses if large enough.

The auditory nerve transports the impulses to the auditory cortex in the brain. The primary auditory cortex then transforms it into basic sensations or meaningless sounds that aren’t understandable. Lastly, the auditory association area combines the sounds into perceptions, which are what we hear.

We can detect where a sound is coming from because we have ears on both the left and right side of our heads. The brain calculates the time difference, or how long it took the sound wave to reach one of the ears.

There are two known theories on how to calculate a sound’s pitch. The frequency theory, applied only to low pitches, says that how long an impulse took to reach the brain determines how low the sound’s pitch is. The place theory, applied on medium to high pitches, relies on the place on the basilar membrane where maximum vibration occurs. Lower-pitched sounds cause maximum vibrations near the beginning of the membrane, while higher pitches cause it near the end.

Loudness can be calculated by the intensity of the sound. A soft sound has a lower amplitude. Because of that, there are fewer vibrations, less movement, and fewer impulses sent. The brain calculates a sound’s loudness based on how fast the impulse reaches it.

THE VESTIBULAR SENSE includes position of head, keeping the head upright and maintaining balance 2 Organs 1. Otolith Organ - Linear acceleration -two membranous sacs called the utricle and the saccule which primary sense horizontal and vertical accelerations 2. Semicircular canal- rotational movements - Each canals is filled with fluid that moves in response to movements of your head. - In the canals are sensors that respond to the movement of the fluid Hair cells

Sensation Group(Bay-ag, Evangelista, Lafuente, Marquez, Ramones, Sueltp)! 1Psychology-6 - The sensors within both the otolith organs and the semicircular canals - They are responsible for the transduction of a mechanical force into an electrical signal and thereby build the interface between the world of accelerations and the brain. Example *When standing on one leg with your arm in the leg, the vestibular sense helps keep you balance *When moving your head(straight, leaning, noding) Motion Sickness - feeling of discomfort, nausea and diziness in a moving vehicle - mismatch between the information from the vestibular sense and the information from your eyes Kinesthetic Sense - informs us about our bodies's positions and motions relative to gravity -It involves being able to detect changes in body position and movements without relying on information from the five senses. Examples: *When riding a bicycle, receptors in your arms and legs send infromation to your brain about the position and movement of your legs and arms *Walking through a parking lot and squeezing through closely parked cars to get yours !

THE CHEMICAL SENSES Olfaction, or Smell !Olfaction is called a chemical sense because its stimuli are various chemicals that are carried by the air. The upper part of the nose has a small area that contains receptor cells for olfaction. The function of the olfactory receptors is transduction, to transform chemical reactions into nerve impulses. Functions of Olfaction:

1. Intensify the taste of the food

2. Warn of potentially dangerous foods

3. Elicit strong memories

Gustatory, or Taste Taste is called a chemical sense because the stimuli are various chemicals. On the surface of the tongue are receptors, called taste buds, for five basic tastes: sweet, salty, sour, bitter, and umami. The function of taste buds is to perform transduction, which means transforming chemical reactions into nerve impulses.

Taste buds, which are shaped like miniature onions, are receptors for taste. Chemical dissolved in saliva activates the taste buds, which produce nerve impulses that eventually reach areas in the brain’s parietal lobe. The brain transforms these nerve impulses in sensations of taste.

Sensitivity Sensitivity to different taste stimuli varies from place to place on the tongue. While any substance can be detected at almost any place on the tongue (except the center), different tastes are best detected in different regions. !We experience flavor when we combine the sensations of taste and smell.

References: Plotnik & Kouyoumdijan’s Introduction to Psychology, Atkinson & Hilgard's Introduction to Psychology, 15th Edition

Sensation Group(Bay-ag, Evangelista, Lafuente, Marquez, Ramones, Sueltp)! ! 1Psychology-6 !THE SOMATOSENSATION

The sense of Touch or somatosensation, also called tactition or mechanoreception is responsible for pressure, temperature, and pain.

The sense of touch is distributed throughout the body.

Nerve endings in the skin and other parts of the body transmit sensations to the brain.

Some parts of the body have a larger number of nerve endings and, therefore, are more sensitive.

There are 4 kinds of touch sensations that can be identified:

1. Cold

2. Heat

3. Contact

4. Pain

Hairs on the skin magnify the sensitivity and act as an early warning system for the body.

Beneath the outer layer of skin there are miniature sensors that are receptors for the sense of touch.

Touch sensors: changes mechanical pressure or temperature variations into nerve impulses that are sent to the brain for processing.

Receptors in the Skin

Skin:

Body’s largest organ

Has 3 layers:

1. Outermost Layer (Epidermis):

➢ is a thin film of dead cells containing no receptors.

➢ Below the dead layer are the first receptors, which look like groups of threadlike extensions

➢ forms the waterproof, protective wrap over the body's surface

2. Middle Layer (Dermis):

➢ Has a variety of receptors with different shapes and functions .

➢ Hair receptors can be found in this layer

➢ consists of connective tissue and cushions the body from stress and strain.

3. Fatty Layer (Hypodermis):

➢ Pacininan Corpuscle can be found in this layer

➢ consists of loose connective tissue and elastin.

Contains some receptors that adapt rapidly and others that adapt slowly

Hair Receptors:

Wrapped around the base of each hair follicle

Responds when hairs are first bent

If hairs remain bent for a period of time, the receptors cease firing (sensory adaptation – prevents our sense of touch from being overloaded)

!Free Nerve Endings:

Threadlike extensions found near the bottom of the outer layer of the skin

Can transmit information about both temperature and pain

Have no complex sensory structures

Sensory Receptors:

Pacinian Corpuscle:

➢ Highly sensitive to touch

Sensation Group(Bay-ag, Evangelista, Lafuente, Marquez, Ramones, Sueltp)! 1Psychology-6➢ Only receptor that responds to vibration

➢ Adapts very quickly.

Merkel Cell:

➢ Located in the palm side of our fingertips

➢ Sensitive to gentle, localized touch

*When pressure (touch), temperature, or pain stimulates the skin’s receptors, they perform transduction and change these forms of energy into nerve impulses. The impulses go up the spinal cord and eventually reach the brain’s somatosensory cortex.

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Somatosensory Cortex:

A narrow strip of cortex

Located in the parietal lobe and extends down its side

Transforms nerve impulses into sensations of touch , temperature, and pain

The right somatosensory cortex receives information from the left side of the body and vice versa

*Compared with touch and temperature, the sense of pain is different because it has no specific stimulus and can be suppressed by psychological factors…. !

CULTURAL DIVERSITY: DISGUST Disgust is a feeling of revulsion or profound disapproval aroused by something unpleasant or offensive. !Cause: Things, happenings or ways of our customs appeal in our senses differently due to barriers of varying culture. Effect: Presence of Disgust !Cultural Factors: 1. Plump Grubs 2. Whale Skin 3. Milk and Blood !

RESEARCH FOCUS:C MIND OVER BODY? Placebo Effect- indicates a powerful mind over body

interaction ! !!PAIN

Pain is a somatic sensation of acute discomfort. It is an unpleasant sensory and emotional experience associated with actual or potential tissue damage, one’s thoughts or beliefs, or environmental stressors.

!HOW PAIN IS MODIFIED?

Gate Control Theory (Melzack & Katz, 2004) - incoming pain must pass through a "gate" located in the spinal cord which determines what information about pain will be sent to the brain. So, it can be opened to allow pain through or closed to prevent pain from being perceived.

Sensation Group(Bay-ag, Evangelista, Lafuente, Marquez, Ramones, Sueltp)! ! 1Psychology-6 The Neural Gate is actually a neural network controlled by the brain. This limits the number of impulses that can be transmitted. It is located in an area of the spinal cord called the Substansia Gelatinosa.

There are two types of nerve fibers in this area:

a) large - sends fast signals and can prevent pain by closing the gate.

b) small - sends slower signals which open the gate. So - when pain occurs it is because the large fibers are off and the small are on, opening the gate.

Contradiction to Gate Control Theory: Endorphins - the body's own pain killers (morphine-like). May explain acupuncture, acupressure, pain tolerance during last two weeks of pregnancy, etc.

PAIN PATHWAYS

Effects of Pain on Body Functioning: !A.Advantages of pain !

Pain motivates the individual to withdraw from damaging situations, to protect a damaged body part while it heals, and to avoid similar experiences in the future.

Pain is a symptom to many other illness. !B.Disadvantages of pain !

Experimental subjects challenged by acute pain and patients in chronic pain experience impairments in attention control, working memory, mental flexibility, problem solving, and information processing speed.Acute and chronic pain are also associated with increased depression, anxiety, fear, and anger.

!Dread great fear or apprehension !Acupuncture a system of complementary medicine that involves pricking the skin or tissues with needles, used to alleviate pain and to treat various physical, mental and emotional conditions !

Sensation Group(Bay-ag, Evangelista, Lafuente, Marquez, Ramones, Sueltp)! 1Psychology-6!!Table 1.1 Sense(Stimulus, Sense Organ, Receptor, Sensation)