SENSATION AND PERCEPTION

SENSATION – is an awareness or a mental process which is aroused because of the stimulation of a sense organ

- it is a one-stage process in which the sensory surface is stimulated and a sensation results

- it is an elementary experience associated with a very simple stimulus

- it briefly refers to the physiological arousal of a sense organ by a stimulus

- sense organs respond directly to the environmental stimuli of odor, touch, light, sound, and taste

PERCEPTION – a process of making sense out of a jumble of so many sensations

- the process of interpreting sensations and events as influenced by set and prior experience – making them meaningful

Acquiring Sensory Awareness:

Conditions in order for sensation to occur:a. Receptor organ stimulation. First essential condition to have a sensory

experience. Stimulus – anything that rouses a sense organ to activity

o Physical energy – ex. heat, light, sound, and pressureo Chemical energy – ex. substances that can be

smelled or tasted

Sense organs – considered as the doorways of the body- is a highly specialized part of the body and is selectively sensitive to a definite stimulus

b. Presence of the receptor cells.- receptor cells detect the stimuli from the environment and

transmit information to the appropriate areas of the brainEx. Rods and cones of the retina

c. Transduction must take place. Transduction – is the process of converting/ transforming a

stimuli into a code of electrochemical impulses which travels to the brain.

- this process takes place in the receptors- the specialized cells transform the physical energy gradually

into electrical voltages known as the generator potentials.

Detecting the stimulus:

ABSOLUTE THRESHOLD – the lower limit of sensitivity or the least quality and quantity of stimulus that can be detected or sensed and perceived consequently

The least amount stimulus necessary to produce a response in a person

There will be no sensation if the stimulus does not reach or go beyond this threshold

STIMULUS THRESHOLDLight

Sound

Taste

Smell

Touch

A candle seen at 30 miles on a dark, clear nightThe tick of a watch under quite conditions at 20 feetOne teaspoon of sugar in 2 gallons of waterOne drop of a perfume diffused into a 3-room apartmentThe wing of a bee falling on your cheek from a distance of 1 cm

SUBLIMINAL THRESHOLD – when there is no sense of awareness and that they escape unnoticedTERMINAL THRESHOLD – when the stimuli reach an increased intensity, they produce pain in the individual being stimulated and make him uncomfortable.

Noting changes in stimulation:

DIFFERENTIAL THRESHOD – the minimum amount of change in the stimulus necessary for the object t o be able to detect

- also known as the discrimination threshold or the just noticeable difference (JND)

- minimum detectable change

Sensory adaptation

THE SENSE ORGANS

Types:1. distal senses – are senses that are sensitive to stimuli coming from

a distance in the outside environmentex. Mother approaching from the other side of the street

2. proximal senses – bring information only when there is direct contact with the objects that stimulate them.

ex. Gustatory sensation which we experience when we eat a ripe mango

olfactory sensation experienced when we smell a sampaguita garland.

VISIO N - one of the distal senses which utilizes the physical characteristic

of light Organ of vision: EYES

Parts of the eye:a. Iris & Pupil– is a group of muscles which operates by reflex action

and gives color to the eye. Contracts when in a bright place, making the pupil smaller, thus controlling much of the brightness of light.

b. Cornea – a white tough membrane which is continuation of the schlera. Transparent in appearance and that provides protection to the inner parts of the eye

c. Lens –adjust the light rays so that whatever one is looking at is sharply focused on the retina

d. Retina – the true organ of vision and is known as the photosensitive area of the eye; where visual transduction takes place2 receptor cells:

1. rods – about 100 million in numbers - used for twilight vision or low light intensity and

enable one to make colorless discrimination - are color blind / see the world in black and white - the rods are better in dim light

2. cones – more than 6 million in numbers, allow us to see the different wavelength of light as different colors/ hues

- the one that interprets colors - when a set of cone is weak, a person is colored blind

3 types of cones:1. sensitive to red2. sensitive to green3. sensitive to blue

2 Types of color blindness: normally

ex. If an individual has 1 type of color blindness – red-green deficiency, a red ball to him appears yellow, and a green appears blue

b. achromatic – a person has no retina- he will see the world without colors at all times, it will only be

black and white

Visual acuity – the individual’s ability to discriminate the details of what he sees

- refers to the clearness/sharpness of vision which can be measured

Snellen Eye Chart – the most common way of measuring this ability 20/20 vision – normal vision, perfect vision, 100% efficiency

Physical Stimulus : LIGHTWAVESSense Organs, Receptors: EYES, RODS AND CONES IN RETINAArea of cerebral Cortex: OCCIPITAL LOBETypes Of Sensation:

Hues – refers to the name of the colors Brightness – the basis of brightness is the energy of the source

light or the intensity of the stimulus ( Yellow appears brighter than red and blue.

- may range from bright to dim

Saturation – associated with the purity or richness of colors

AUDITION

Organ for Hearing: EARS- sensitive to sound waves

Sound waves – mechanical vibrations in the air

3 Main parts of the Ear1. Outer Ear;

a. Pinna (concha) – a skin covered cartilage protruding on the side of the head that collects sound wavesb. Auditory canal c. Eardrum (tympanic membrane) – a movable diaphragm activated by sound waves

2. Middle Ear:o Ossicles – systems of bones

Malleus/ hammer - attached firmly to the eardrum Incus (anvil) Stapes (Stape) – attached firmly to the oval window Oval window – conducts the sound waves to the cochlea

3. Inner Ear: Cochlea (Greek word for “snail”) - a fluid-filled coiled or spiral formed structure where

transduction takes place- contains: basilar membrane – composed of hair cells

(“cilia”)which is responsible for the release of neurotransmitters

- cilia – contains the Organ of Corti which makes the hair cells receptors for hearing

Type of Sensitivity: AuditoryPhysical Stimulus: Sound WavesSense Organ, Receptors: Ears: hair Organs Of CortiArea of Cerebral Cortex: Temporal LobeTypes of Sensations:

a. Pitch – the qualitative dimension of hearing correlated with the frequency of the sound waves that constitute the stimulus

- refers to the highness or lowness of a soundb. loudness – an intensity dimension of hearing correlated with amplitude of the sound waves constituting the stimulusc. complexity –different sounds / differences of sounds

noise – complex sounds composed of many frequencies not in harmonious relation with one another

d. timbre – is the characteristic quality of a musical tone (piano or a violin)

Decibel Scale

The decibel scale is used primarily to compare sound intensities although it can be used to compare voltages.

Decibels

Typical sound

OLFACTORY Organ of Smelling: NoseType of sensitivity: OlfactoryPhysical Stimulus: Gaseous SubstancesReceptors: Hair Cells in Olfactory EpitheliumArea of Cerebral Cortex: None (processed in the lower brain centers)

0 threshold of hearing

10 rustle of leaves in gentle breeze

10 quiet whisper

20 average whisper

20-50 quiet conversation

40-45 hotel; theater (between performances)

50-65 loud conversation

65-70 traffic on busy street

65-90 train

75-80 factory (light/medium work)

90 heavy traffic

90-100 Thunder

110-140 jet aircraft at takeoff

130 threshold of pain

140-190 space rocket at takeoff

NoseYour nose helps you breathe and smell. Air enters the nose through the nostrils and passes into a large space called the nasal cavity. Nerve cells in the olfactory bulb collect information about smells in the air and pass that information to the olfactory tract and onto the brain.

Adaptation – a process in which a sense gradually ceases to respond to a constant stimulus

Seven Basic Molecules or Smells that can be perceived or determined by the brain: (Boeree, 2003)

a. Floral (flowery) b. Pepperminty (minty)c. Musky - perfumed. Pungent – spices, vinegare. Camphoraceous – mothballsf. Ethereal – dry-cleaning fluidg. Putrid (putrial) – rotten eggs, raw/ decaying fish or meat

Nose and SmellPeople use their noses to smell. Most people can identify about 10,000 different types of odors.

GUSTATION-referred to as a chemical sense (together with the olfactory

sense)Type of Sensitivity: GustatoryPhysical Stimulus: Soluble SubstancesSense Organ, Receptors: Tongue; taste cells in the taste buds

PARTS of the TONGUE a. Papillae – slight elevations of the tongue

- taste buds lie in the crevices between the papillaec. Taste buds – are shaped like a flask and each one has an opening like

a pore- there are approximately 10,000 taste buds in the human adult

tonguec. taste receptors – taste cells that are found in the taste buds

- 15-20 taste cells arranged in budlike form on the tip of the tongue

- Reproduce themselves every seven to ten days- As individual ages, there is a decrease in the cells and small

amount of cells are replacedArea of Cerebral Cortex: Parietal LobeTypes of Sensation:

Primary Tastes: a. Salty – felt at the tip and along the sides of the tongueb. Sweet – most felt at the tip of the tonguec. Sour – on the sidesd. Bitter – at the base or on the back

- these sensations are combined with the sense of smell to give various foods their unique tastesRECEPTOR CELLS OF THE TONGUE

AGEUSIA – a disorder of taste when the nerves responsible for taste are damaged

CUTANEOUS- said to be as the reality senses [when we feel something with

our skin, we are convinced that something is really there]- help us adapt to and survive to changing temperatures - pain receptors warn us of harmful objects in the environment

Physical Stimulus: Mechanical or Thermal StimulationSense Organ, Receptors: Skin; Free Nerve EndingsSKIN – contains the largest receptors of any sensory system in the body

because it covers the entire body

Structure of the SkinHuman skin has three layers. The epidermis forms the outer, protective layer. The dermis contains hair roots, sweat and oil glands, nerves, and blood vessels. The fat layer attaches the skin to internal organs.

Layers of the Skin:a. Epidermis – outer layer; b. Dermis – intermediate or the middle layerc. Subcutaneous/adipose – innermost layer

Free Nerve Endings – considered as the sense organs of the skin- are not equally distributed in the skin

Receptors for different Skin Sensations:a. Meissner’s Corpuscles –receptor for touchb. Pacinian Corpuscles – receptors for pressure

- responsible for pressure-sensitivity- second most numerous

c.Ruffini Nerve Endings – receptor for hot Physiologic Zero – if the temp is 32 degrees centigrade, no sensation

is felt, neither hot or coldBaseline temp: 28˚C – 37˚C

- a difference of 0.01˚C- 8˚C – an indication of slight fever

d. Krause end bulbs – receptor for colde. Free nerve endings – receptor for physical pain

- based on studies found out to be the most numerous

PROPRIOCEPTORS- the general term used to refer to the sense of body position- involves to senses:

o Kinesthetic Senseo Vestibular Sense

A. Kinesthetic Sense - sense of movement and posture

Kinesthesia – is the sense of relating where the body parts are with respect to each other

- gives information about body movements and positions- the receptor cells are in the nerve endings of the muscles,

tendons and jointsReceptor cells – are simple neurons that branch off from the central nervous system and lead into muscles, tendons, and joint linings

Physical Stimulus: Change in position of body partsSense Organ, Receptors: Muscles, tendons, and joints; nerve endingsArea of Cerebral Cortex: Parietal LobeType of Sensation: Movement of body parts

B. Vestibular Sense - Sense of balance- Also called as the equilibratory or labyrinthine sense- Deals with the total body position in relation to gravity

and with motion of the body as a whole- Located near the cochlea in the inner ear

- 3 Semicircular Canals in the cochlea contains fluids that moves whenever we turn or rotate our head

- lining these canals are small hair cells that respond with a nerve when the fluid pushes against them

- -aside from the semicircular canals, the sense organ of balance also includes two other cavities in the bone near the cochlea

o Utriculuso Sacculus

- these are cavities filled with small crystals that respond to gravity

- respond to the change in position or tilt of the head

Type of Sensitivity: EquilibriumPhysical Stimulus: Change in Rotary motion; Change in Rectilinear

Motion; Body PositionRotary Motion – sense when moving on a circular movement

- semicircular canals are sense organs for rotation- the receptors respond only to changes in rate of rotations,

that is, to acceleration or decceleration Rectilinear – is the motion that one makes when he is making

movement in a straight lineSense Organ, Receptors: Ear; Semicircular Canals; ear; vestibuleType of Sensation: Turning or Spinning acceleration; deceleration;

upright or tilted