Sensation.1

Sensations can be defined as Sensations can be defined as the passive process the passive process of bringing information from the outside world of bringing information from the outside world

into the body and to the brain.into the body and to the brain. The process is The process is passive in the sense that we do not have to be passive in the sense that we do not have to be consciously engaging in a "sensing" process.consciously engaging in a "sensing" process.

How sensation and perception work How sensation and perception work together:together:

Sensation occurs:Sensation occurs: sensory organs absorb energy from a sensory organs absorb energy from a

physical stimulus in the environment.physical stimulus in the environment. sensory receptors convert this energy into sensory receptors convert this energy into

neural impulses and send them to the neural impulses and send them to the brain.brain.

Perception follows:Perception follows: the brain organizes the information and the brain organizes the information and

translates it into something meaningful.translates it into something meaningful.

In order to measure these events, In order to measure these events, psychologists use THRESHOLDS.psychologists use THRESHOLDS.

1.1. Threshold - a dividing line between what has detectable Threshold - a dividing line between what has detectable energy and what does not.energy and what does not.

2.2. Difference Threshold - the minimum amount of stimulus Difference Threshold - the minimum amount of stimulus intensity change needed to produce a noticeable change.intensity change needed to produce a noticeable change.

the greater the intensity (ex., weight) of a stimulus, the the greater the intensity (ex., weight) of a stimulus, the greater the change needed to produce a noticeable change.greater the change needed to produce a noticeable change.

3.3. Signal-Detection Theory - detection of a stimulus involves Signal-Detection Theory - detection of a stimulus involves some decision making process as well as a sensory some decision making process as well as a sensory process. Additionally, both sensory and decision making process. Additionally, both sensory and decision making processes are influenced by many more factors than just processes are influenced by many more factors than just intensity.intensity.

A.A. Noise - how much outside interference exists.Noise - how much outside interference exists.

B.B. Criterion - the level of assurance that you decide must be Criterion - the level of assurance that you decide must be met before you take action. met before you take action.

The Nature of Sensory The Nature of Sensory ProcessesProcesses

1.1. Sensory ThresholdsSensory Thresholds

2.2. Absolute thresholdAbsolute threshold

3.3. Sensory adaptationSensory adaptation

4.4. Difference threshold (just noticeable Difference threshold (just noticeable difference)difference)

the minimum amount of stimulus intensity the minimum amount of stimulus intensity change needed to produce a noticeable change.change needed to produce a noticeable change.

the greater the intensity (ex., weight) of a the greater the intensity (ex., weight) of a stimulus, the greater the change needed to stimulus, the greater the change needed to produce a noticeable change. produce a noticeable change.

Visual senseVisual sense

the visual system works on sensing and the visual system works on sensing and perceiving light waves. Light waves perceiving light waves. Light waves vary in their length and amplitude.vary in their length and amplitude.

Structure of The EYE:Structure of The EYE: 1.1. Cornea - the round, transparent area that allows light to Cornea - the round, transparent area that allows light to

pass into the eye.pass into the eye.

2.2. Lens - the transparent structure that focuses light onto the Lens - the transparent structure that focuses light onto the retina.retina.

3.3. Retina - inner membrane of the eye that receives Retina - inner membrane of the eye that receives information about light using rods and cones. The information about light using rods and cones. The functioning of the retina is similar to the spinal cord - both functioning of the retina is similar to the spinal cord - both act as a highway for information to travel on.act as a highway for information to travel on.

4.4. Pupil - opening at the center of the iris which controls the Pupil - opening at the center of the iris which controls the amount of light entering the eye. amount of light entering the eye.

5.5. Rods & Cones - many more rods (approximately 120 million) Rods & Cones - many more rods (approximately 120 million) than cones (approx 6.4 million).than cones (approx 6.4 million).

a)a) cones - visual receptor cells that are important in daylight cones - visual receptor cells that are important in daylight vision and color vision.vision and color vision.

the cones work well in daylight, but not in dim lighting. This is the cones work well in daylight, but not in dim lighting. This is why it is more difficult to see colors in low light.why it is more difficult to see colors in low light.

most are located in the center of the retina...called the FOVEA, most are located in the center of the retina...called the FOVEA, which is a tiny spot in the center of the retina that contains which is a tiny spot in the center of the retina that contains ONLY cones...visual acuity is best here.ONLY cones...visual acuity is best here.

b)b) rods - visual receptor cells that are important for night vision rods - visual receptor cells that are important for night vision and peripheral vision.and peripheral vision.

the rods are better for night vision because they are much the rods are better for night vision because they are much more sensitive than cones.more sensitive than cones.

Are these triangles real? Are these triangles real? They appear to be, They appear to be, because the brain because the brain automatically fills in lines automatically fills in lines that are missing. But if you that are missing. But if you block out parts of the block out parts of the picture, the white triangle picture, the white triangle vanishes.vanishes.

The black line in the The black line in the back seems much back seems much longer than the one in longer than the one in the front because your the front because your brain assumes it is brain assumes it is seeing the effects of seeing the effects of perspective. When the perspective. When the background is background is removed, the lines are removed, the lines are seen to be equal.seen to be equal.

Color Vision Theories:Color Vision Theories:1.1. Trichromatic Theory Trichromatic Theory

this theory indicates that we can receive 3 types of colors (red, this theory indicates that we can receive 3 types of colors (red, green, and blue) and that the cones vary the ratio of neural green, and blue) and that the cones vary the ratio of neural activity (Like a projection T.V.). The ratio of each color to the activity (Like a projection T.V.). The ratio of each color to the other then determines the exact color that we see. other then determines the exact color that we see.

2.2. Opponent-Process Theory Opponent-Process Theory

color perception depends on the reception of pairs of color perception depends on the reception of pairs of antagonist colors. Each receptor can only work with one color at antagonist colors. Each receptor can only work with one color at a time so the opponent color in the pair is blocked out. Pairs = a time so the opponent color in the pair is blocked out. Pairs = red-green, blue-yellow, black- white (light-dark). red-green, blue-yellow, black- white (light-dark).

Seeing In ColorSeeing In Color

Auditory senseAuditory senseSounds are formed when objects vibrate, thus, Sounds are formed when objects vibrate, thus,

the sound waves set-up by these vibrating the sound waves set-up by these vibrating bodies are transmitted through the air to the bodies are transmitted through the air to the

ear drum.ear drum.

Process of hearing:Process of hearing:1.1. Outer Ear Outer Ear The concha/pinna is the external ear part that assembles the The concha/pinna is the external ear part that assembles the

sound vibrations to the auditory canal/ meatus to the eardrum.sound vibrations to the auditory canal/ meatus to the eardrum.

2.2. Middle EarMiddle Ear The ear drum vibrates and transmits sound waves to the three The ear drum vibrates and transmits sound waves to the three

small bones small bones Hammer(malleus)Hammer(malleus) Anvil(incus)Anvil(incus) Stirrups(stapes)Stirrups(stapes)

3.3. Inner EarInner Ear 2 structures:2 structures:a.a. Sem-circular canalSem-circular canalb.b. Cochlea which contains the sensitive structure of hearing.Cochlea which contains the sensitive structure of hearing.

Auditory Phenomena:Auditory Phenomena:Dimensions of tone:Dimensions of tone:1.1. Pitch – depends on the number of vibrations per second.Pitch – depends on the number of vibrations per second.

2.2. Loudness – correlated with the amplitude of sound wavesLoudness – correlated with the amplitude of sound waves - the degree of displacement of the vibrations from its source.- the degree of displacement of the vibrations from its source.

3.3. Timbre – tonal quality of sound and the complexity of vibrations.Timbre – tonal quality of sound and the complexity of vibrations.a)a) NoiseNoiseb)b) Musical harmonyMusical harmony

4.4. Resonance – occurs when another object vibrates as the result Resonance – occurs when another object vibrates as the result of regular impulses sent out by another vibrating body.of regular impulses sent out by another vibrating body.

5.5. Masking – interference of one sensory stimulus by another.Masking – interference of one sensory stimulus by another.

Theories of HearingTheories of Hearing1.1. Place Theory of pitch – each part of the basilar membrane is so Place Theory of pitch – each part of the basilar membrane is so

attuned that it responds only to one frequency.attuned that it responds only to one frequency.

2.2. Valley Theory – suggests that the frequency of stimulus may be Valley Theory – suggests that the frequency of stimulus may be represented by fibers in the auditory nerve responding represented by fibers in the auditory nerve responding independently that the frequency is represented by the independently that the frequency is represented by the composite valley.composite valley.

3.3. Frequency Theory – assumes that neural impulses arising in the Frequency Theory – assumes that neural impulses arising in the organ of corti are activated by the basilar membrane of organ of corti are activated by the basilar membrane of vibration rather than the source.vibration rather than the source.

4.4. Travelling Wave Theory – when a sound of a given frequency Travelling Wave Theory – when a sound of a given frequency enters the ear, a wave travels along the basilar membrane and enters the ear, a wave travels along the basilar membrane and displaces it at a maximum amount at a certain point.displaces it at a maximum amount at a certain point.

Olfaction Olfaction (Odor sense)(Odor sense)

Gaseous particles which the nose smells Gaseous particles which the nose smells in order to be perceived. Smell has in order to be perceived. Smell has

more direct route to the brain.more direct route to the brain.

Phenomena of OlfactionPhenomena of Olfaction The stronger the sensation of odor, the more it somes in The stronger the sensation of odor, the more it somes in

contact with the organ of smell.contact with the organ of smell.

A.A. Olfactory Adaptation – occurs after being subjected to the Olfactory Adaptation – occurs after being subjected to the same kind of odor for a specific time.same kind of odor for a specific time.

B.B. Impaired Olfactory Sensitivity – This is the effects of Impaired Olfactory Sensitivity – This is the effects of smoking, colds, etc. blocking the odor which comes in-smoking, colds, etc. blocking the odor which comes in-contact with epithelial cells.contact with epithelial cells.

Theories of OlfactionTheories of Olfaction

1.1. Traditional theory – odorous substances give off gaseouos Traditional theory – odorous substances give off gaseouos particles which stimulates the nose.particles which stimulates the nose.

2.2. Radiation Theory – states that the Olfactory Receptors Radiation Theory – states that the Olfactory Receptors radiate a variety of wave-length bands and that different radiate a variety of wave-length bands and that different vapors, when entering the nostrils, absorb different vapors, when entering the nostrils, absorb different bands.bands.

Gustation Gustation (Taste Qualities)(Taste Qualities)

Stimuli of taste are soluble substances in the Stimuli of taste are soluble substances in the saliva. saliva.

Composed of 4 known taste qualities which Composed of 4 known taste qualities which are:are:

1.1. SweetSweet2.2. SaltySalty3.3. SourSour

4.4. bitterbitter

The TongueThe Tongue

Circumvallate Papillae – for Circumvallate Papillae – for bitter taste (back of the bitter taste (back of the tounge)tounge)

Fungiform Papillae – sour Fungiform Papillae – sour ans sweet (sides and tips)ans sweet (sides and tips)

Gustatory PhenomenaGustatory Phenomena The sense of taste is further The sense of taste is further

complicated by the fact that complicated by the fact that one taste may counteract by one taste may counteract by the other.the other.

Doesn’t only involve the sense Doesn’t only involve the sense of taste but also sensations like of taste but also sensations like pressure, warmth, cold, pain, pressure, warmth, cold, pain, and odors.and odors.

Gustatory sense is usually Gustatory sense is usually affected by the other senses. affected by the other senses.

Sensations of the taste buds Sensations of the taste buds are carried to the central are carried to the central nervous system by 3 cranial nervous system by 3 cranial nerves:nerves:

1.1. FacialFacial2.2. Glosso-PharyngealGlosso-Pharyngeal3.3. Vagus nervesVagus nerves

Somesthesia Somesthesia (skin sense)(skin sense)

4 different skin senses4 different skin senses1.1. PressurePressure

2.2. TouchTouch3.3. TemperatureTemperature

4.4. PainPain These senses differ from the sensitivity of These senses differ from the sensitivity of

stimulation within certain areas of the stimulation within certain areas of the body/skin.body/skin.

Relative Frequencies of Skin sense in Relative Frequencies of Skin sense in descending order:descending order:1.1. Pain – the immediate stimulus of pain is injury to tissues.Pain – the immediate stimulus of pain is injury to tissues.

2.2. Pressure – greatly varies for different parts of the body. Pressure – greatly varies for different parts of the body. - caused by the deforming/bending of the skin.- caused by the deforming/bending of the skin.

3.3. Cold – temperature ranges from 10 to 30CCold – temperature ranges from 10 to 30C

4.4. Warmth – “ “ “ 35 to 70CWarmth – “ “ “ 35 to 70C

Phenomenon of Somesthesia:Phenomenon of Somesthesia: Adaptation to pressure is rapid while pain is rather slow.Adaptation to pressure is rapid while pain is rather slow.

PerceptionPerceptionPerception can be defined as Perception can be defined as the active the active process of selecting, organizing, and process of selecting, organizing, and

interpreting the information brought to interpreting the information brought to the brain by the senses.the brain by the senses.

Gestalt Principles of Gestalt Principles of Perceptual Organization Perceptual Organization

1.1. figure-ground - this is the fundamental way we figure-ground - this is the fundamental way we organize visual perceptions. When we look at an organize visual perceptions. When we look at an object, we see that object (figure) and the object, we see that object (figure) and the background (ground) on which it sits. background (ground) on which it sits.

2.2. simplicity/pragnanz (good form) - we group simplicity/pragnanz (good form) - we group elements that make a good form. However, the elements that make a good form. However, the idea of "good form" is a little vague and idea of "good form" is a little vague and subjective. Most psychologists think good form is subjective. Most psychologists think good form is what ever is easiest or most simple. what ever is easiest or most simple.

3.3. proximity - nearness=belongingness. Objects that are close proximity - nearness=belongingness. Objects that are close to each other in physical space are often perceived as to each other in physical space are often perceived as belonging together.belonging together.

4.4. similarity - As you probably guessed, this one states that similarity - As you probably guessed, this one states that objects that are similar are perceived as going together. objects that are similar are perceived as going together.

5.5. continuity - we follow whatever direction we are led. continuity - we follow whatever direction we are led.

6.6. common fate - elements that move together tend to be common fate - elements that move together tend to be grouped together. grouped together.

7.7. closure - we tend to complete a form when it has gaps.closure - we tend to complete a form when it has gaps.

Illusions Illusions

an incorrect perception an incorrect perception caused by a distortion of caused by a distortion of

visual sensations.visual sensations.

The shaded circles seem to The shaded circles seem to form an X made of form an X made of spheres. But if you rotate spheres. But if you rotate the image 180°, the same the image 180°, the same circles form an X made of circles form an X made of cavities, since the brain cavities, since the brain assumes that light comes assumes that light comes from above.from above.

A.A. Reversible Figures - ambiguous sensory information that Reversible Figures - ambiguous sensory information that creates more than 1 good form. creates more than 1 good form.

B.B. Impossible Figures - Impossible Figures - objects that can be objects that can be represented in 2-represented in 2-dimensional pictures but dimensional pictures but can not exist in 3-can not exist in 3-dimensional space dimensional space despite our perceptions. despite our perceptions.

THE PERCEPTION THE PERCEPTION OF PAIN OF PAIN

Pain is an unpleasant yet important function for Pain is an unpleasant yet important function for survival: warning system (but not all pain is survival: warning system (but not all pain is

needed for survival).needed for survival).

There are two different pathways to the There are two different pathways to the brain on which pain can travel:brain on which pain can travel:

1.1. fast pathways - registers localized pain (usually sharp fast pathways - registers localized pain (usually sharp pain) and sends the information to the cortex in a fraction pain) and sends the information to the cortex in a fraction of a second. EX. - cut your finger with a knife.of a second. EX. - cut your finger with a knife.

2.2. slow pathways - sends information through the limbic slow pathways - sends information through the limbic system which takes about 1-2 seconds longer than system which takes about 1-2 seconds longer than directly to the cortex (longer lasting, aching/burning).directly to the cortex (longer lasting, aching/burning).

Factors in Pain Factors in Pain PerceptionPerception

1.1. expectations - research shown that our expectations about expectations - research shown that our expectations about how much something will hurt can effect our perception.how much something will hurt can effect our perception.

Melzack - indicated that believing that something will be Melzack - indicated that believing that something will be very painful helps us prepare for it.very painful helps us prepare for it.

2.2. personality - people with negative types of personalities personality - people with negative types of personalities often have more pain. often have more pain.

3.3. mood - bad moods, angry, unhappy, etc, can lead to the mood - bad moods, angry, unhappy, etc, can lead to the experience of increased pain.experience of increased pain.

So, it seems that our brains can regulate, control, So, it seems that our brains can regulate, control, determine, and even produce pain.determine, and even produce pain.

THEORIES OF PAIN THEORIES OF PAIN PERCEPTIONPERCEPTION

1.1. Gate Control Theory (Melzack & Walls, 1965) - incoming pain Gate Control Theory (Melzack & Walls, 1965) - incoming pain must pass through a "gate" located in the spinal cord which must pass through a "gate" located in the spinal cord which determines what information about pain will be sent to the determines what information about pain will be sent to the brain. So, it can be opened to allow pain through or closed to brain. So, it can be opened to allow pain through or closed to prevent pain from being perceived.prevent pain from being perceived.

The Gate - actually a neural network controlled by the brain. The Gate - actually a neural network controlled by the brain. Located in an area of the spinal cord called the Substansia Located in an area of the spinal cord called the Substansia Gelatinosa. There are two types of nerve fibers in this area:Gelatinosa. There are two types of nerve fibers in this area:

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

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

Since the gate is controlled by the brain, he factors discussed Since the gate is controlled by the brain, he factors discussed earlier (expectations, mood, personality) influence the earlier (expectations, mood, personality) influence the functioning of the gate.functioning of the gate.