Sensation and Perception

Sensationand

Perception

Group 3

Sensation- Is the process of accepting the stimulus by the sense.

Stimulus - is any form of energy that can

cause awareness or change to the consciousness (light waves, sound waves, temperature, chemical state –liquid, solid, gaseous, etc.).

- These stimuli are then modified and accepted by the accessory structures (eyes, ears, nose, tongue, skin, etc.)

Receptors- are specialized cells responsible

for detecting specific type of energy as a result of transduction.

- Transduction is the process of changing the stimulus sense into energy for neural activity.

Psychophysics - is the relationship between the physical and psychological environment. It connects the external and internal world of an individual. Psychophysics aims to examine the sensitivity of the individual to various stimuli. Then it determines the psychological perception on the stimulus.

Absolute Threshold is the least quality and quantity of a stimulus that can be sensed and perceived consequently. It is the smallest intensity of energy that can be perceived 50% of the time.

SENSES ABSOLUTE THRESHOLD

Light Sound Touch Taste Smell

 Sees a candlelight 30 miles away on a clear, dark night Hears the tick of a watch 20 feet away under silent situation. Feels wing of a fl 1 cm. away from the cheek Tastes the sweetness of one teaspoon of sugar in 2 gallons of water. Smells the scent of one drop of perfume diffused in a 3-room apartment

Difference thresholdor Just Noticeable Difference (JND) is the minimum difference in intensity between two small stimuli when caused by a smallest change. It does not only determine the presence or absence of stimulus but also detect whether the two small stimuli are different or the same.

Visual Sensation

Rods- Allow humans to see in black, white, and

shades of gray in dim light- Mostly in the periphery- Take 20 – 30 minutes to fully adapt to

darknessCones- Enable humans to see color and fine

detail in adequate light, but that do not function in dim light

- Mostly in the fovea- Adapt fully to darkness in 2 – 3 minutes

Hue is the fundamental color, marked by the intensity of wavelength of the light.

Saturation is associated with the purity of color. There are colors that have single, more intense wavelength than other wavelengths.

Brightness conforms to the total degree of all the wavelengths constituting light.

Color Vision

Auditory Sensation

Coding of FrequenciesThe auditory system can react to

various quantities of sound intensities. The greater degree of sound is produced, the more intense is the response of the neuron. The range of specific neuron in the auditory nerve is based on both frequency and intensity of the stimulus. The difference in frequency can be explained by place theory and volley theory.

Frequency Theory (Frequency Matching: Volley Theory)William Rutherford pioneered the frequency theory on pitch discrimination. The membrane vibrates faster if the tone is high. This causes a greater number of neurons to send the information faster into auditory nerve at a particular time. Pitch depends on how fast the stimulus is sent to the brain by its frequency per second.

Somatic Sensation

- Sensations arising from the skin — such as touch, pressure, cold, warmth, and pain — and from the muscles, tendons, and joints — such as the position of the limbs and pain — are known as somatic sensations.- All somatic sensations start with the excitation of sensory receptors located in the appropriate tissue — skin, muscle, joints etc.

Gustatory Sensation

Gustation- The sensation of taste

Five basic tastes- Sweet- Sour- Salty- Bitter

Olfactory Sensation

- Olfaction or the sense of smell is somehow considered to be one of the lower senses.- Odors of gaseous state are senses in the upper part of the nose. Molecules enter through the nostrils (Opening) or from the back of the mouth (oral cavity) into the nasal cavity. Hence, olfaction is a dual sense; it can smell internally (oral cavity) and externally (nasal cavity).

Proprioceptionfrom Latin proprius, meaning

"one's own," and perception — is one of the human senses. There are between nine and 21 in all, depending on which sense researcher you ask. Rather than sensing external reality, Proprioception is the sense of the orientation of one's limbs in space.

a. Vestibular Sense (balance)-the sensations of body rotation and of gravitation and movement)

b. Kinesthesia (posture and movement)-is the perception of body movements. It involves being able to detect changes in body position and movements without relying on information from the five senses.

Perception-The process by which sensory

information is actively organized and interpreted by the brain

- Stimulus is recognized by the sense organ – resulting to sensation.

- Perception interprets meaningful experiences in totality. The meanings on how the brain organized previous and present knowledge or information are obtained.

Grouping- is when certain elements or objects

are put together forming a whole pattern according to the following principles:

a. Proximityb. Similarityc. Continuityd. Closuree. Figure and Ground

a. ProximityProximity occurs when elements

are placed close together. They tend to be perceived as a group.

b. SimilaritySimilarity occurs when objects look

similar to one another. People often perceive them as a group or pattern.

c. ContinuityContinuation occurs when the eye is

compelled to move through one object and continue to another object.

d. ClosureClosure occurs when an object is

incomplete or a space is not completely enclosed. If enough of the shape is indicated, people perceive the whole by filling in the missing information.

C. Figure and GroundFigure ground perception is the

tendency to discriminate between target and background stimuli. The stimulus we perceive as being the target is referred to as the figure.

ConstancyConstancy is the capacity to

perceive stable properties belonging to objects even if there are changes in their features.

a. Size Constancyb. Shape Constancyc. Texture Constancyd. Color Constancye. Brightness Constancy

a. Size ConstancySize constancy refers to our ability

to see objects as maintaining the same size even when our distance from them makes things appear larger or smaller.

b. Shape ConstancyShape constancy is the tendency

to perceive the shape of a rigid object as constant despite differences in the viewing angle.

c. Texture ConstancyTexture constancy reveals the

true nature or property of an object. If the object is closer or nearer, the details or features will be visualized. If the same object is seen farther, it will look smoother and the details cannot be seen.

d. Color ConstancyColor Constancy of the same

object can vary in accordance with light illumination. The lightning of an object can appear different but its true color remains the same. A bright lightning on a hue will make the colors appeal lighter and less lightning will make the colors appear darker.

e. Brightness ConstancyBrightness constancy refers to our

ability to recognize that color remains the same regardless of how it looks under different levels of light.